ALBERT

Description: 〈p〉Publication date: 15 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 218〈/p〉 〈p〉Author(s): Athanassios Athanassiou, Alexandra A.E. van der Geer, George A. Lyras〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Eastern Mediterranean islands, most of which belong to the Aegean archipelago, have a complex biogeographic history, which puts its stamp on their fauna and flora. A now extinct but most important faunal component, in terms of geographic spread and taxonomic diversity, are the elephants. The Eastern Mediterranean islands are particularly rich in Pleistocene endemic elephant localities, which preserve samples of extinct endemic populations. These were either descendants of the European straight-tusked elephant 〈em〉Palaeoloxodon antiquus〈/em〉 or the Southern mammoth, 〈em〉Mammuthus meridionalis〈/em〉. Their presence, history and palaeobiogeography has been documented only for Cyprus, Crete, Kasos, Rhodes, Tilos, Kýthera, Naxos, and Delos. For six other islands only anecdotal references exist in the literature: Kálymnos, Astypálaia, Milos, Sériphos, Kýthnos and Paros. Here, we provide an update on previously published specimens and taxa, describe previously undescribed specimens that were relocated in museum collections, as well as recently excavated specimens, and put these in the context of island palaeobiogeography. We conclude that dwarf elephants, endemic to their palaeo-island, lived on the islands of palaeo-Cyclades, Astypálaia, Crete, Kasos–Kárpathos–Saría, Tilos, Rhodes and Cyprus, whereas the elephants from Kephallenía, Kálymnos and Kýthera are indistinguishable on the species level from mainland 〈em〉Palaeoloxodon antiquus〈/em〉. Elephant fossils of unresolved taxonomic status are reported from five present-day islands. The Eastern Mediterranean endemic elephants likely derived from separate and independent colonisation events from the mainland. No island supported more than one proboscidean species at any time. We found that isolation had no effect on the degree of dwarfism, but that there exists a threshold of about 6–10 km distance between the island and the mainland, below which no dwarfism evolved, likely as a result of genetic contact with the mainland population. We also found that although island area is correlated with the degree of dwarfism in elephants, other factors, such as the level of interspecific competition, may limit this degree.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 218〈/p〉 〈p〉Author(s): Weizhe Chen, Dan Zhu, Philippe Ciais, Chunju Huang, Nicolas Viovy, Masa Kageyama〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Climate and atmospheric CO〈sub〉2〈/sub〉 strongly influence the vegetation distribution and the terrestrial carbon storage. Process-based dynamic global vegetation models (DGVM) are important tools for simulating past vegetation dynamics and carbon cycle; yet the link between spatial gradients of climate and vegetation cover in geological past has received less attention. In this study, we simulate the distribution of vegetation under three CO〈sub〉2〈/sub〉 levels for two climate states, the Last Glacial Maximum (LGM) and Pre-industrial (PI) climate with fire activated or deactivated using the ORCHIDEE-MICT DGVM. Results show that elevated CO〈sub〉2〈/sub〉 and warmer climate promote global total tree cover but the impacts are different between forest biomes. Regional tree cover is highly regulated by mean annual precipitation (MAP) especially in the tropics, and by temperature for the boreal-arctic tree line. Based on quantile nonlinear regressions, we analyze the MAP threshold at which maximum tree cover is reached. This threshold is significantly reduced with elevated CO〈sub〉2〈/sub〉 for tropical and temperate trees. With higher CO〈sub〉2〈/sub〉, increased tree cover leads to reduced fire ignition and burned area, and provides a positive feedback to tree cover, especially in Africa. Besides, in our model, increasing CO〈sub〉2〈/sub〉-induced enhancement of gross primary productivity (GPP) is more prominent for tropical trees than for temperate and boreal trees, and for dry regions than wet regions. This difference explains why CO〈sub〉2〈/sub〉 is the major factor influencing forest cover in the tropics. It also highlights that special attention should be paid to collect paleo-vegetation data across savannas-forest transition in dry regions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 218〈/p〉 〈p〉Author(s): Taoliang Zhang, Rujian Wang, Leonid Polyak, Wenshen Xiao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Distribution and composition of coarse particles (〉250 μm) were investigated in 13 sediment cores from the Chukchi margin, western Arctic Ocean. Petrographic clast identification is supplemented by XRF core scanning, EDS analysis of coal fragments, and AMS 〈sup〉14〈/sup〉C dating of planktic foraminifera for age control. Coal debris distribution is also investigated in surface sediments of the study region for provenance interpretation. The sediment-core study focuses on the interval between the Last Glacial Maximum and the Holocene for constraining provenance and timing of the deglacial discharge. We find that this interval is characterized by a distinct enrichment in sedimentary rock fragments, including coal. Comparison with longer stratigraphic records indicates that this composition is unique for the time interval since at least Maine Isotope Stage 5. Based on the timing, interpreted provenance, and geographic distribution of the coal enrichment, we conclude that the most likely primary source was the deglacial discharge from the Mackenzie drainage basin of the Laurentide Ice Sheet (LIS). The identified coal-bearing layer, also expressed in the XRF sulfur record, can be thus used as a stratigraphic marker for the LIS discharge to the Arctic Ocean during the last deglaciation.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 217〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 15 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 218〈/p〉 〈p〉Author(s): Ebru Albayrak〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Although today the Asian elephant, 〈em〉Elephas maximus〈/em〉, exists in a number of fragmented and isolated populations in south and southeast Asia, its historical range was extended westwards as far as Iraq. Because 〈em〉E. maximus〈/em〉 is rarely preserved in fossil form and the remains from these peripheral ancient populations are scant, not much is known about their relationship to modern Asian elephant. The elephants in Tigris-Euphrates region, sometimes referred to as 〈em〉E. maximus asurus〈/em〉, had died out during the first half of the first millennium BCE. Some researchers have supported the idea that a living Asian elephant population inhabited the Euphrates-Tigris region in the late Holocene. The remains of ancient Asian elephant from the southeastern part of Turkey are known from several studies, and Gavur Lake Swamp (southeast Turkey) in particular is the only natural locality that yielded both dental and postcranial remains in southwest Asia. In this study new specimens including mandibles, isolated teeth, scapula, humeri and vertebras from Gavur Lake Swamp were studied. Moreover, the wear patterns of lower molars are examined in detail as they have an ambiguous pattern, which is mostly associated with 〈em〉Palaeoloxodon antiquus〈/em〉 and is not very common in recent Asian elephant. Comparisons with the recent Asian elephant teeth may point out that the extinct westernmost population of Asian elephant in Gavur Lake Swamp might have local or regional features in wear pattern in the lower molars.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 218〈/p〉 〈p〉Author(s): Alexander M. Wilson, James K. Russell, Brent C. Ward〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Volcanic rocks erupted within glacial environments offer powerful paleoenvironmental insights. These glaciovolcanoes and their deposits serve as proxies that inform on the paleo-presence, distribution and thickness of past glaciers. We investigate the paleoenvironmental implications of three Mid to Late Pleistocene volcanic deposits in the Garibaldi volcanic belt of southwestern British Columbia, Canada. We use these data to inform a simple geometric model that constrains paleo-glacier distributions in the southern Canadian Cordillera. The three volcanoes are used to recover: i) a coalesced mountain ice sheet in late Marine Isotope Stage (MIS) 4, and possibly into MIS 3 (up to ∼49.1 ± 5.5 ka), ii) major and rapid degradation of glaciers during the late, MIS 6 to 5e transition (by 141 ± 12.9 ka), and, iii) a coalesced mountain ice sheet, or continental ice sheet that existed during MIS 15 (598 ± 7.5 ka).〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 221〈/p〉 〈p〉Author(s): Trine Kellberg Nielsen, Søren Munch Kristiansen, Felix Riede〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Preservation and exposure of sediments is a prerequisite for finding archaeological traces. Regional geological history plays a significant and potentially biasing role in the reconstruction of the biogeographical distribution of Pleistocene hominins, particularly in previously glaciated regions. Here we present a digital geoarchaeological approach to a qualitative assessment of this archaeological bias in southwestern South Scandinavia. First, we identify time periods where the region was accessible and suitable for past humans. Our results show that only the longer Pleistocene interstadials offered terrestrial access in combination with potentially suitable habitats. Second, we present an extended digital geoarchaeological prospection of lacustrine, fluvial and palaeosol deposits and relict landscape features. This review guides the identification of preserved sediments of Pleistocene origin and confirms that Pleistocene deposits and landscape features are present in the study area, however, generally in a poor state and low quantity/quality. Third, we map the modern occurrence of sediment exposure through natural processes and anthropogenic activities. Triangulating the cumulated results of these three steps we identify three target areas which offer promising combinations of these factors: A) the Holsted and Rødding hill islands in Central South Jutland; B) the moraine landscape of Central East Jutland, and C) the intersections of buried valleys on the east coast of Jutland. To test the robustness of our prediction, it is necessary to regularly survey open quarries and exposures in these target areas. This should be the aim of future studies, ideally conducted, we suggest, using citizen science approaches that include relevant stakeholders.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 221〈/p〉 〈p〉Author(s): Omotayo Anuoluwapo Fadina, Igor Martins Venancio, Andre Belem, Carla Semiramis Silveira, Denise de Castro Bertagnolli, Emmanoel Vieira Silva-Filho, Ana Luiza S. Albuquerque〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The sediment core GL-1248, collected from the continental slope off northeastern Brazil, was used to reconstruct mercury (Hg) variations in NE South American continental margin and understand its variability in response to paleoclimate changes over the past 128 ka. Mercury concentrations in GL-1248 ranged between 14.95 and 69.43 ng/g, showing a glacial-interglacial pattern with higher (lower) concentrations in the glacial period (interglacial period). Parallel trends of Hg and XRF-Fe plots suggest that following atmospheric Hg deposition onto the continent, Hg is incorporated with Fe compounds before transportation and eventual immobilization at the NE Brazil continental slope. Peaks of Hg and Fe/Ca ratio peaks occurred concurrently during certain Heinrich Stadials, indicating that Hg is transported from the continent alongside fluvial sediments during periods of increased precipitation and erosion in NE Brazil continent. Mercury concentrations varied with periodicities of 56 ka and 900 yr suggesting glacial-interglacial changes and millennial-scale variability, respectively. Total Hg and total organic carbon are poorly correlated, although the latter likely influenced Hg sequestration into marine sediments during millennial-scale events between 60 ka and 30 ka. Altogether, our results suggest that the atmosphere is the primary source of Hg to GL-1248 and glacial-interglacial climate variations were the major determinant of atmospheric Hg deposition. Furthermore, increased precipitation during millennial-scale events played a secondary role by enhancing Hg transport to the continental slope of NE Brazil.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 220〈/p〉 〈p〉Author(s): Nicole S. Khan, Benjamin P. Horton, Simon Engelhart, Alessio Rovere, Matteo Vacchi, Erica L. Ashe, Torbjörn E. Törnqvist, Andrea Dutton, Marc P. Hijma, Ian Shennan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Determining the rates, mechanisms, and geographic variability of relative sea-level (RSL) change following the Last Glacial Maximum (LGM) provides insight into the sensitivity of ice sheets to climate change, the response of the solid Earth and gravity field to ice-mass redistribution, and constrains statistical and physical models used to project future sea-level rise. To do so in a scientifically robust way requires standardized datasets that enable broad spatial comparisons that minimize bias. As part of a larger goal to develop a unified, spatially-comprehensive post-LGM global RSL database, in this special issue we provide a standardized global synthesis of regional RSL data that resulted from the first ‘Geographic variability of HOLocene relative SEA level (HOLSEA)’ meetings in Mt Hood, Oregon (2016) and St Lucia, South Africa (2017). The HOLSEA meetings brought together sea-level researchers to agree upon a consistent protocol to standardize, interpret, and incorporate realistic uncertainties of RSL data. This special issue provides RSL data from ten geographical regions including new databases from Atlantic Europe and the Russian Arctic and revised/expanded databases from Atlantic Canada, the British Isles, the Netherlands, the western Mediterranean, the Adriatic, Israel, Peninsular Malaysia, Southeast Asia, and the Indian Ocean. In total, the database derived from this special issue includes 5634 (5290 validated) index (n = 3202) and limiting points (n = 2088) that span from ∼20,000 years ago to present. Progress in improving the standardization of sea-level databases has also been accompanied by advancements in statistical and analytical methods used to infer spatial patterns and rates of RSL change from geological data that have a spatially and temporally sparse distribution and geochronological and elevational uncertainties. This special issue marks the inception of a unified, spatially-comprehensive post-LGM global RSL database.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 221〈/p〉 〈p〉Author(s): Xueqin Zhao, Lydie Dupont, Rachid Cheddadi, Martin Kölling, Hanane Reddad, Jeroen Groeneveld, Fatima Zohra Ain-Lhout, Ilham Bouimetarhan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Morocco is an area subject to recurrent severe droughts, desertification and an increasing land degradation. It is within a Mediterranean hotspot of biodiversity as it harbors many threatened endemic species such as the argan tree (〈em〉Argania spinosa〈/em〉). In this context, past climate records are needed to analyze the impact of climate variability on the occurrence and future persistence of these endemic species. In order to evaluate the impact of past climate changes on the endemic Argan tree in southern Morocco, we reconstructed its modern range using an extensive pollen dataset. The modern pollen distribution off southwestern Morocco was then utilized to interpret the high-resolution pollen record with complementary micro-charcoal and XRF element records from a marine sediment core GeoB8601-3 off Cape Ghir in southwestern Morocco covering the last three millennia. This multi-proxy study has shown clear evidence of wetter conditions resulting in higher fluvial input which could be correlated with a negative mode of the North Atlantic Oscillation (NAO), in contrast to the published pollen and XRF element records from another nearby core that showed limited effect of climate changes. On the other hand, clear opposite trend between the pollen occurrences of 〈em〉Argania spinosa〈/em〉 and the fire frequency was observed throughout our fossil record. The increase of 〈em〉Argania spinosa〈/em〉 pollen occurrences, along with herbaceous taxa, and lower fire frequency might suggest an increase in human impact on the landscape leading to a sparse vegetation cover and subsequently increased erosion. The reconstructed pollen-based vegetation, micro-charcoal-based fire activities and geochemical changes in our marine record suggest interplay of climate and anthropogenic effects on the landscape.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 221〈/p〉 〈p〉Author(s): Rivka Rabinovich, Gadi Herzlinger, Rani Calvo, Florent Rivals, Steffen Mischke, Gali Beiner〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Early sites along the Dead Sea Transform (southern Levant), among them the Erq el Ahmar Elephant Site, are key points in understanding hominin and mammal migration out of Africa and into Eurasia. The late Prof. Tchernov had begun an intensive campaign to expose the faunal remains at the site, but unfortunately was unable to conclude his study. Based on interim reports and geomorphological descriptions, we were aware of numerous elephant remains found and left 〈em〉in situ〈/em〉. The Erq el Ahmar Elephant Site is a controversial site. There are those who see it as the earliest Pleistocene hominin site in the area, while others consider it a paleontological site without any hominin involvement. We returned to the site to try to resolve this controversy. In a systematic excavation, we succeeded in exposing the previously uncovered elements, exposed more material and currently better understand the deposition sequence. However, the task was very challenging, since the skeletal elements were very fragile and required careful exposure and conservation, both 〈em〉in situ〈/em〉 and in the laboratory, before they could be studied. A series of elements were found partially superimposed. Several elements of the skull, an almost complete tusk, vertebrae, ribs, a scapula and limb bones were found. Mammoth diagnostic traits were identified in the teeth and tusk. However, very few skeletons of early mammoths are known from the region. Have we exposed the most complete 〈em〉Mammuthus rumanus〈/em〉 skeleton? Tooth microwear indicates leaf-browsing dietary traits, similar to that of other 〈em〉M. rumanus〈/em〉 of this period. In addition, the recent excavations have revealed the potential of the site in understanding the evolution and dispersal of proboscidean species out of Africa during the Plio-Pleistocene, adding another focal point to the southern Levant along this route.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 221〈/p〉 〈p〉Author(s): Sophie Montuire, Aurélien Royer, Anna Lemanik, Olivier Gilg, Natalya Sokolova, Aleksandr Sokolov, Emmanuel Desclaux, Adam Nadachowski, Nicolas Navarro〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The genus 〈em〉Dicrostonyx〈/em〉 (the collared lemming) is undoubtedly the small mammal best adapted to the extreme conditions of the arctic environment. The Palearctic collared lemming has been described in numerous European Late Pleistocene localities up to south of France and Croatia. This species experienced climate-driven changes through time, changes mainly observed as repetitive pulses of pan-continental migration, and it thus became a typical indicator of glacial conditions. Using geometric morphometrics on molars, we evaluate the shape changes occurring during the last 100 ky over some dispersal events in Western Europe. The results point out that 〈em〉Dicrostonyx torquatus〈/em〉 has a large intra-population variation with a homogenous morphology, regardless of the origin of the individuals. A temporal trend leading to a more complex tooth with a differentiated anterior loop on the first lower molar was observed. An additional effect of the distance from the core populations was also described with a more peculiar shape for the most western populations of France. These temporal and geographical trends might relate to the different migratory pulses documented from ancient DNA haplotypes.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 221〈/p〉 〈p〉Author(s): Michelle C. Langley, Chris Clarkson, Sean Ulm〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The pace of research undertaken in Sunda (Southeast Asia) through to Sahul (Greater Australia) has increased exponentially over the last three decades, resulting in spectacular discoveries ranging from new hominin species, significant extension to the age for first human occupation in the region, as well as the identification of what is currently the oldest known rock art in the world. These breakthroughs cast the archaeological record of complexity in Sunda, Sahul, and Wallacea in an entirely different light to that of several decades ago, placing it on an equal footingto that of Africa, Asia, and Europe. The archaeological record of these regions now points to rich and diverse early modern human (〈em〉Homo sapien〈/em〉) societies engaged in complex symbolic and technological behaviours demonstrating capacities for innovation and self-expression found in all modern human groups now around the globe. Here we provide a comprehensive review of all Pleistocene symbolic evidence reported for Sahul, Sunda, and Wallacea to date. We explore how recent findings have changed our perceptions of the first modern human colonists and our understanding of the origins and development of the rich and diverse cultures that arose in each region through time.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0277379118310023-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 221〈/p〉 〈p〉Author(s): Ali R. Vahdati, John David Weissmann, Axel Timmermann, Marcia S. Ponce de León, Christoph P.E. Zollikofer〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Understanding Late Pleistocene human dispersals from Africa requires understanding a multifaceted problem with factors varying in space and time, such as climate, ecology, human behavior, and population dynamics. To understand how these factors interact to affect human survival and dispersal, we have developed a realistic agent-based model that includes geographic features, climate change, and time-varying vegetation and food resources. To enhance computational efficiency, we further apply machine learning algorithms. Our approach is new in that it is designed to systematically evaluate a large-scale agent-based model, and identify its key parameters and sensitivities. Results show that parameter interactions are the major source in generating variability in human dispersal and survival/extinction scenarios. In realistic scenarios with geographical features and time-evolving climatic conditions, random fluctuations become a major source of variability in arrival times and success. Furthermore, parameter settings as different as 92% of maximum possible difference, and occupying more than 30% of parameter space can result in similar dispersal scenarios. This suggests that historical contingency (similar causes – different effects) and equifinality (different causes – similar effects) are primary constituents of human dispersal scenarios. While paleoanthropology, archaeology and paleogenetics now provide insights into patterns of human dispersals at an unprecedented level of detail, elucidating the causes underlying these patterns remains a major challenge.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 221〈/p〉 〈p〉Author(s): Elan J. Levy, Orit Sivan, Gilad Antler, Boaz Lazar, Mordechai Stein, Yossi Yechieli, Ittai Gavrieli〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉During the late Quaternary several hypersaline lakes occupied the tectonic depression of the Dead Sea Basin, depositing sequences of primary-evaporitic mineral phases: aragonite (CaCO〈sub〉3〈/sub〉), gypsum (CaSO〈sub〉4〈/sub〉·2H〈sub〉2〈/sub〉O) and halite (NaCl). Aragonite and gypsum were the dominant primary mineral phases during the glacial periods and their formation required significant import of bicarbonate (HCO〈sub〉3〈/sub〉〈sup〉−〈/sup〉) and sulfate (SO〈sub〉4〈/sub〉〈sup〉2−〈/sup〉) ions to the lake. While bicarbonate was likely derived from dissolution of calcite in the watershed, the sources of sulfate remained elusive. Here we investigate and quantify the long-term sulfate reservoir changes in the deep waters (hypolimnion) of Lake Lisan (the last glacial Dead Sea) using concentrations and stable isotopes of sulfur in pore-fluids from the cores that were drilled at the lake floor (2010–11) by ICDP (International Continental Drilling Program). From ca. 117ka, pore-fluid sulfate concentrations increased and the brine attained supersaturation with respect to gypsum, peaking during the last glacial maximum (LGM; ca. 20ka). Stable isotopes of pore-fluid sulfate (δ〈sup〉34〈/sup〉S and δ〈sup〉18〈/sup〉O) are similar to the values found in bulk sulfate minerals from the nearby Mount Sedom salt diapir. We suggest that relatively diluted and cool paleo-epilimnion water facilitated dissolution of halite and anhydrite (CaSO〈sub〉4〈/sub〉) of the Mt. Sedom salt diapir, resulting in a localized increase in solution density. Subsequently, this solution sank and mixed with saline hypolimnion water, simultaneously replenishing chloride, sodium and sulfate reservoirs, while diluting it with respect to other solutes. The mixing of the calcium-rich gypsum saturated hypolimnion and the sulfate-rich sinking brine from above resulted in gypsum supersaturation.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 221〈/p〉 〈p〉Author(s): Encarni Montoya, Jordi Pedra-Méndez, Esther García-Falcó, Miriam Gómez-Paccard, Santiago Giralt, Teresa Vegas-Vilarrúbia, Fred W. Stauffer, Valentí Rull〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Coastal wetlands have been proposed as highly threatened by the ongoing and future climatic change, including projected sea-level changes as an additional forcing factor compared to more inland locations. The limited knowledge generated to date in this topic has been primarily focused on those areas attaining a high population density, and rarely deals with long-term (〉50 years) dynamics. Here we present the first Holocene palaeoecological study carried in the Orinoco Delta, in NE Venezuela. The record presented here contains sediments from the last 6200 years and is located in a river-shore swamp dominated by the palm 〈em〉Mauritia flexuosa〈/em〉. Current human occupation is almost restricted to small settlements of the Warao indigenous culture, closely related to the use of 〈em〉M. flexuosa〈/em〉 and other palm species present in the zone. The results show the occurrence of three well-distinguished palynological zones: (i) from 6200 to 5200 cal yr BP, characterised by mixed rainforest and other taxa related to salinity (coastal-like), low (negative) values of magnetic susceptibility and magnetic grain size, absence of transported clays, and the highest macrocharcoal particles abundance; (ii) from 5200 to 2950 cal yr BP, marked by a replacement of the mangrove-like vegetation by a more inland mixed-swamp forest community with low levels of charcoal, and (iii) from 2950 cal yr BP to present-day, characterised by the establishment of the current vegetation community, dominated by 〈em〉M. flexuosa〈/em〉, and an increasing trend in the charcoal curve since the last 700 years. A combination of regional (climatic changes) and local (sediment ontogeny) has been proposed as the key drivers influencing the vegetation succession recorded. The stabilisation of the sea-level that occurred during the mid-Holocene would have favoured the transgression of the coastal line, with the migration of the coastal-like vegetation seawards. Synchronous to this event, a trend towards drier conditions has been reported in the close Cariaco record, that could have also influenced the vegetation replacement. Between 3800 and 2800 years ago, the increased ENSO variability registered in Cariaco may have played a key role in the expansion of the 〈em〉Mauritia〈/em〉 palm community. It is suggested that in our location, the potential inhabiting human populations were differently influenced by these environmental changes. First, the disappearance of the coastal resources could have favoured land abandonment, whereas the increase in the abundance of the palm might be influential for the arrival of other inland cultures that were previously used to manage 〈em〉Mauritia〈/em〉. This sequence shows the importance of the ecosystem services for the location inhabitants, highlighting the abandonment of the mid-Holocene culture coeval with the disappearance of its ecosystem. These results also provide information about the sensitivity and resilience in facing external stressors of both humans and vegetation, and will be valuable tools for managing the future of this ecosystem.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 22 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): C. Rabouille, B. Dennielou, F. Baudin, M. Raimonet, L. Droz, A. Khripounoff, P. Martinez, L. Mejanelle, P. Michalopoulos, L. Pastor, A. Pruski, O. Ragueneau, J.-L. Reyss, L. Ruffine, J. Schnyder, E. Stetten, M. Taillefert, J. Tourolle, K. Olu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Carbon and silicon cycles at the Earth surface are linked to long-term variations of atmospheric CO〈sub〉2〈/sub〉 and oceanic primary production. In these cycles, the river-sea interface is considered a biogeochemical hotspot, and deltas presently receive and preserve a major fraction of riverine particles in shallow water sediments. In contrast, periods of glacial maximum lowstand were characterized by massive exports of sediments to the deep-sea via submarine canyons and accumulation in deep-sea fans. Here, we calculate present-day mass balances for organic carbon (OC) and amorphous silica (aSi) in the terminal lobe complex of the Congo River deep-sea fan as an analogue for glacial periods. We show that this lobe complex constitutes a megasink with the current accumulation of 18 and 35% of the OC and aSi river input, respectively. This increases the estimates of organic carbon burial by 19% in the South Atlantic Ocean in a zone representing less than 0.01% of the basin. These megasinks might have played a role in carbon trapping in oceanic sediments during glacial times.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 221〈/p〉 〈p〉Author(s): Marie Protin, Irene Schimmelpfennig, Jean-Louis Mugnier, Ludovic Ravanel, Melaine Le Roy, Philip Deline, Vincent Favier, Jean-François Buoncristiani, Georges Aumaître, Didier L. Bourlès, Karim Keddadouche〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Investigation of Holocene extents of mountain glaciers along with the related naturally-driven climate conditions helps improve our understanding of glacier sensitivity to ongoing climate change. Here, we present the first Holocene glacial chronology in the Mont-Blanc massif (Argentière glacier) in the French Alps, based on 25 〈em〉in situ〈/em〉-produced cosmogenic 〈sup〉10〈/sup〉Be dates of moraines and glacial bedrocks. The obtained ages from mapped sequences of moraines at three locations reveal that the glacier retreated from its Lateglacial extent and oscillated several times between ∼11.7 ka and ∼10.4 ka, i.e. during the Younger Dryas/Early Holocene (YD/EH) transition, before substantially retreating at ∼10.4 ka. Climate conditions corresponding to the past extents of Argentière glacier during the YD/EH transition (∼11 ka) and the Little Ice Age (LIA) were modelled with two different approaches: by determining summer temperature differences from reconstructed ELA-rises and by using a Positive Degree Day (PDD) mass-balance model. The ELA-rise reconstructions yield a possible range of temperatures for the YD/EH transition that were lower by between 3.0 and 4.8 °C compared to the year 2008, depending on the choice of the ELA sensitivity to temperature. The results from the PDD model indicate temperatures lower by ∼3.6–5.5 °C during the YD/EH transition than during the 1979–2002 period. For the LIA, our findings highlight the role of local precipitation changes, superimposed on the dominant temperature signal, in the detailed evolution of the glacier. Overall, this study highlights the challenge that remains in accurately inferring paleoclimate conditions from past glacier extents.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 221〈/p〉 〈p〉Author(s): Adi Torfstein〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The history of Levant paleo-hydrology, which is expressed by the absolute water level record of the Dead Sea over the last 70 kyrs, has been shown to be closely coupled with global climate patterns, and specifically argued to be modulated by northern hemisphere climate systems. Here, this coupling is rigorously tested and the absolute lake level curve is compared with a variety of globally distributed climate archives and used to deconvolve the processes controlling regional climate and hydrology. Considering that different archives are based on different sampling resolutions, and hence might have inherently different recording sensitivities, each of the chosen archives was interpolated and then smoothed at varying temporal resolutions. The synthetic curves, ranging between temporal smoothing resolutions between 10 years and 15 kyrs were compared to the similarly processed lake level record over the last 60 kyrs. The best fit to the Dead Sea lake level was found to be with Antarctica temperatures and atmospheric CO〈sub〉2〈/sub〉 levels. Greenland temperatures and proximal archives such as the Soreq Cave and the Dead Sea lithological record, all yielded weaker correlations to the lake level curve.〈/p〉 〈p〉An exception to the strong correlation between Levant climate and atmospheric CO〈sub〉2〈/sub〉 concentrations, is observed during Marine Isotope Stage (MIS) 5e, at a time when the Dead Sea watershed was exposed to very weak Mediterranean westerly systems that imposed hyperarid conditions, and a superposition of southern derived systems that delivered short but intense precipitation to the region. At this time, Antarctic temperatures cross a temperature threshold beyond 1 °C above present. It is suggested that this exceptional warming phase induces a reorganization of global and regional climate systems influencing the Levant.〈/p〉 〈p〉These results have two important implications. The first is the understanding that global temperatures and atmospheric CO〈sub〉2〈/sub〉 concentrations impose the first order control over Levant climate. The second, is that the Antarctic records can be used as synthetic lake level proxies, extending the absolute lake level curve to ca. 800 ka, compared with its current span of 70 kyrs. Considering the importance of the Dead Sea lake level curve as a regional paleo-climatic-hydrologic recorder, the new synthetic curve provides a prominent proxy of Levant hydro-climate history.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 220〈/p〉 〈p〉Author(s): Jonathan Keinan, Miryam Bar-Matthews, Avner Ayalon, Tami Zilberman, Amotz Agnon, Amos Frumkin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Levant region of Israel, located along the Eastern Mediterranean Sea, is characterized by Mediterranean climate, but sixty km eastwards towards the Dead Sea Rift Valley (DSRV), the region rapidly becomes a ‘rain shadowʼ desert. Speleothems from the Mediterranean climate zone continuously grew throughout several glacial/interglacial cycles, indicating that water was always available in the unsaturated zone. Their δ〈sup〉18〈/sup〉O variations match global and regional climate changes, with the Eastern Mediterranean Sea being the major control on their δ〈sup〉18〈/sup〉O values, as evident from the similarity between the speleothems and the planktonic foraminifer 〈em〉G. ruber〈/em〉 records. In contrast, speleothems along the central and southern segments of the DSRV grew mainly during last glacial periods coinciding with the higher stands of Lake Lisan, the precursor of the present-day Dead Sea. This paper discusses the newly discovered Zalmon Cave speleothems, located in the northern segment of the DSRV shedding light on the hydrological conditions along the rift during last glacial. Unlike speleothems located further south along the DSRV, Zalmon Cave speleothems grew both during glacial and interglacial periods. However, during last glacial their δ〈sup〉18〈/sup〉O values, shifted to lower values by ∼1–2‰ relative to speleothems from central Israel coinciding also with the largest difference in δ〈sup〉18〈/sup〉O values between Zalmon Cave speleothems and the marine record. The data suggest that a change of the westerlies' storm tracks occurred during most of the last glacial period, which resulted in increased rainfall in the northern DSRV providing freshwater input during the otherwise relatively ‘drierʼ glacial.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 31 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): David J.A. Barrell, Aaron E. Putnam, George H. Denton〈/p〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 221〈/p〉 〈p〉Author(s): R. Belmaker, B. Lazar, M. Stein, N. Taha, R. Bookman〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The laminated sequences of the Holocene Dead Sea (DS) and its late Pleistocene precursor Lake Lisan comprise primary aragonite and fine detritus that record the hydro-climate conditions of the late Quaternary Levant. Several studies suggested that the primary aragonite precipitated due to mixing between runoff that brought bicarbonate to the lake and the lake's Ca-chloride brine. However, the factors controlling the aragonite precipitation were not robustly established. Here, we addressed this issue by measuring the chemical composition (pH, Na〈sup〉+〈/sup〉, K〈sup〉+〈/sup〉, Ca〈sup〉2+〈/sup〉, Mg〈sup〉2+〈/sup〉, Sr〈sup〉2+〈/sup〉, Cl〈sup〉−〈/sup〉, Br〈sup〉−〈/sup〉, B, alkalinity) of flood plumes where the mixing occurs. The results indicate that: (a) Na〈sup〉+〈/sup〉, Mg〈sup〉2+〈/sup〉, K〈sup〉+〈/sup〉 and Cl〈sup〉−〈/sup〉 are conservative during the floodwater-brine mixing whereas Ca〈sup〉2+〈/sup〉 and Sr〈sup〉2+〈/sup〉 adsorb on flood's suspended sediments; (b) Boron (an important alkalinity species in the DS) adsorption on flood's suspended load enabled the bicarbonate that entered the lake via runoff to react with the Ca〈sup〉2+〈/sup〉 thus facilitating aragonite precipitation (c) Dissolution of calcite dust blown from the Sahara during winter storm is the source of bicarbonate which is required for aragonite precipitation. These observations explain the occurrence of aragonite laminae both during the wet last glacial period and during the dry last 3000yr. Although the water input during these two periods was completely different, they both were characterized by high dust fluxes and a stratified lake configuration in which the boron concentrations in the epilimnion were low enough to enable the bicarbonate that entered the lake via runoff to react with the lake brine Ca〈sup〉2+〈/sup〉 and precipitate aragonite.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 220〈/p〉 〈p〉Author(s): Ye Yang, Cong-Qiang Liu, Jérôme Van der Woerd, Sheng Xu, Li-Feng Cui, Zhi-Qi Zhao, Qi-Lian Wang, Guo-Dong Jia, François Chabaux〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Based on Terrestrial Cosmogenic Nuclide (TCN) constraints from depth profiles of one granitic regolith from Wumingshan and five fluvial terraces from Xianshuihe and Zagunao rivers, we discuss the timing of the last deglaciation, the landscape-scale denudation and fluvial incision rates across the eastern Tibetan Plateau, in relation to previous work. We present a three-dimensional-graph visualization approach and corresponding constraints to better assess the feasibility and applicability of cosmogenic nuclides depth-profile dating. The exposure age (older than 19.4 ka) of the Wumingshan regolith corresponds to the retreat of the palaeo-Daocheng ice cap, which covered the Yidun terrane during the Last Glacial Maximum (LGM). Most basin-wide denudation rate data in the eastern Tibetan Plateau are lower than 130 mm/ka (47%, n = 90), which is consistent with the Wumingshan regolith denudation rate (lower than 52.8 mm/ka), and thus indicate that the landscape-scale denudation has been stabilized after the last deglaciation. Considering the reduction of integrated bulk density due to the accumulation of lower-density loess, we estimate mean exposure ages of Xianshuihe and Zagunao river terraces of 4.0 ± 0.7 ka, 5.9 ± 0.3 ka, 13.4 ± 2.0 ka, and 16.6 ± 1.4 ka. The observed increase in incision rate from 0.39 mm/yr over long timescale (∼600 ka) to 5.88 mm/yr over the last 15 ka at the Xianshuihe river site is probably due to the transition from glacial to interglacial climatic conditions. The fewer abandoned terraces along the Zagunao river after the Heinrich event 1 (H1) indicates that the climate change during the latest glacial-interglacial transition impacted less the landscape evolution in a relatively lower elevation area. Comparison with previously reported fluvial incision rates elsewhere across the eastern margin of the Tibetan Plateau indicates that incision rates are mainly influenced by abrupt climate change or intensified summer monsoon since the early Holocene, but probably controlled by regional tectonic uplift or fluvial headward retreat as the timescale increases. Overall, we propose a synthetic pattern of landscape evolution mainly dominated by long-term tectonic uplift together with fluvial headward erosion, episodically influenced by climatic change throughout the late Quaternary.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 220〈/p〉 〈p〉Author(s): Mingming Zhang, Zhaojun Bu, Ming Jiang, Shengzhong Wang, Shasha Liu, Qing Jin, Penghan Shi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The density of maar lake type peatlands in the Changbai Mountain areas, northeast (NE) China is among the highest in the world. These deposition systems include both peat and limnic deposits, providing valuable sites to study their evolutionary history shaped by their sensitivity to climate-forced state shifts. To investigate the maar lake-mire shift in response to hydroclimatic variability, we examined developmental history of the Jinchuan peatland based on sedimentary facies, grain-size, physical and chemical properites, plant macrofossils and peat basal age. The results indicate that the Jinchuan peatland mainly originated from paludification in a maar lake from approximately 7000 cal. BP. Its water level continuously increased since the Middle Holocene, reaching the peak during the period of 5000–4000 cal. yr BP. The outward expansions of Jinchuan peatland suggest a climate–driven model based on which water level variability superimposes the underlying basin morphology. The hydroclimatic variability and peatland development history can be divided into three periods. From 12 to 7 ka cal. BP, the increasing East Asian summer monsoon (EASM) was the major water vapor source of Jinchuan peatland. The strong evaporation effects induced by the strong Winter Asian winter monsoon (WAWM) and the maximum sea surface temperatures (SSTs) of Japan Sea might have changed the Jinchuan maar lake into dry upland. From 7 to 4 ka cal. BP, the maximum EASM and increasing Westerly jet (WJ) provided water vapor for the peatland. The decreasing EAWM and SSTs of Japan Sea resulted in decreased evaporation effects. The moisture and water level in Jinchuan peatland gradually increased. The peat covered 68.97% of the area during this period. Since 4 ka cal. BP, the decreased EASM and the maximum WJ provided water vapor for the Jinchuan peatland. The weak EAWM and the lower SSTs of Japan Sea induced lower evaporation effects. The moisture and water level in the peatland reached the maximum. Subsequently, peat area further expanded and covered the remaining 31.03% area. This study reveals a remarkable link between the maar lake-mire shift and hydroclimatic variability, which is significant for future prediction of maar lake-mire ecosystem shifts under global climate change.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0277379119304330-fx1.jpg" width="261" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 220〈/p〉 〈p〉Author(s): Andy I.R. Herries, Justin W. Adams, Renaud Joannes-Boyau, Brian Armstrong, Stephanie Baker, Alex F. Blackwood, Giovanni Boshian, Matt V. Caruana, Paul Penzo-Kajewski, Ashleigh Murszewski, Douglass S. Rovinsky〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Drimolen Palaeocave System in the ‘Fossil Hominid Sites of South Africa’ UNESCO World Heritage Site is well known for numerous remains of early hominins such as 〈em〉Paranthropus robustus〈/em〉 and early 〈em〉Homo〈/em〉. These hominin fossils, along with bone tools and notably diverse accumulation of non-hominin primates and fauna, have all been excavated from the 'Main Quarry' area of the site where extensive lime-mining took place. Here we report the first radiometric age of 1.712 ± 0.269 Ma for hominin bearing deposits associated with the DNH7 〈em〉Paranthropus robustus〈/em〉 cranium in the Main Quarry area of the site, which is consistent with recent biochronological estimates. This age is similar to recent estimates for Swartkrans Member 1 Hanging Remnant (somewhere between 2.3 and 1.8 Ma) which also contains 〈em〉Paranthropus〈/em〉 and early 〈em〉Homo〈/em〉. Simultaneously, we integrate the newly radiometrically dated Main Quarry deposits with a new fossil deposit, the Drimolen Makondo, discovered in 2013, that is situated some 50 m up the hill to the west from the Main Quarry. It has experienced only limited disturbance from mining but much more extensive erosion. Preliminary excavations and analysis have revealed that the Makondo infill is older than the Main Quarry, dating to 2.706 ± 0.428 Ma. Its greater age is confirmed by biochronology. The Makondo thus overlap with the suggested end of deposition of 〈em〉Australopithecus〈/em〉 bearing Sterkfontein deposits, although it is yet to yield any hominin remains. These new dates for the two Drimolen Palaeocave System deposits indicates that, contrary to prior age estimates, the Drimolen site as a whole records the critical hominin and faunal turnover in South African palaeocommunities that occurred around 2.3–1.7 Ma. Finally, as the Drimolen Makondo represents a rare example of a pre-2 Ma fossil bearing deposit in the Gauteng exposures of the Malmani dolomite, we also integrate our results into the greater South African record of palaeodeposit formation (most of which occur between ∼2.0 and 1.0 Ma). An analysis of the age of palaeocave infillings across the Malmani dolomite suggests that, as is classically the case with karst, the height within the dolomite is broadly correlated to their age, although with some notable exceptions that are likely related to localised geological features. Our analysis also indicates that most caves have undergone some form of secondary karstification related to a younger phase of cave formation, contrasting with models that suggest the cavities all formed at the same time and that infill is related to erosion and the opening up of cave passages. As such, the reason that few pre-2 Ma deposits have been identified in the Gauteng exposures of the Malmani dolomite is probably because these older caves have been eroded away. Identifying such early caves is critical in understanding whether earlier hominins may have once existed in South Africa or if erosion of older deposits (or an absence of speleogenesis at this time) has made such early periods absent from the geological record.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 221〈/p〉 〈p〉Author(s): Thaís Rabito Pansani, Fellipe Pereira Muniz, Alexander Cherkinsky, Mírian Liza Alves Forancelli Pacheco, Mário André Trindade Dantas〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the present study, the paleoecology (diet and niche width) of Late Quaternary megamammals that inhabited the Brazilian Intertropical Region (BIR) was assessed at two sites in the states of Bahia and Mato Grosso do Sul. The δ〈sup〉13〈/sup〉C analyses suggest a generalist diet for 〈em〉Notiomastodon platensis〈/em〉, 〈em〉Palaeolama major〈/em〉, 〈em〉Holmesina paulacoutoi〈/em〉 and 〈em〉Glyptotherium〈/em〉 sp., while 〈em〉Equus neogeus〈/em〉 was a grazer with a diet consisting exclusively of C〈sub〉4〈/sub〉 grasses, and 〈em〉Eremotherium laurillard,〈/em〉 a predominant browser with a diet consisting predominantly of C〈sub〉3〈/sub〉 plants. A distinct diet pattern was inferred for one species: 〈em〉Toxodon platensis〈/em〉 with a mixed-diet preferring C〈sub〉4〈/sub〉 grasses in Mato Grosso do Sul but predominantly the C〈sub〉3〈/sub〉 feeder in Bahia. These results show a high ecological plasticity of this species and may suggest distinct ecological pressures or different vegetation configurations in the two regions. Diet reconstitutions based on δ〈sup〉13〈/sup〉C analyses suggest that an open savanna-like landscape predominated in both areas. The δ〈sup〉18〈/sup〉O values reveal that Mato Grosso do Sul could have experienced wetter climatic conditions than Bahia during the Late Quaternary, suggesting a humid corridor in midwestern Brazil, or that there were different contents of δ〈sup〉18〈/sup〉O of water sources between these areas. Hence, we assume that the same faunistic composition in different geographical areas is not enough to delimit the ecosystems of the BIR, and we recommend that the definitions of BIR should be revised to include more refined paleoclimate data. Other studies around the world should consider the same for delimitations of zoogeographic regions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 221〈/p〉 〈p〉Author(s): Jernej Jevšenak〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An extended European tree-ring network was compiled from various sources of tree-ring data from Europe, northern Africa and western Asia. A total of 1860 tree-ring chronologies were used to compare correlation coefficients calculated with aggregated day-wise and month-wise mean temperature, sums of precipitation and standardised precipitation-evapotranspiration index (SPEI). For the daily approach, climate data were aggregated over periods ranging from 21 to 365 days. Absolute correlations calculated with day-wise aggregated climate data were on average higher by 0.060 (temperature data), 0.076 (precipitation data) and 0.075 (SPEI data). Bootstrapped correlations are computationally expensive and were therefore calculated on a 69.4% subset of the data. Bootstrapped correlations indicated statistically significant differences between the daily and monthly approach in approximately 1% of examples. A comparison of time windows used for calculations of correlations revealed slightly later onset and earlier ending day of the year for the daily approach, while the largest differences between the two approaches arise from window lengths: Correlations calculated with day-wise aggregated climate data were calculated using fewer days than the monthly approach. Differences in the onset and ending dates of periods for the daily and monthly approaches were greater for precipitation and SPEI data than for temperature data.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 6 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Hayley C. Cawthra, Richard M. Cowling, Sergio Andò, Curtis W. Marean〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The South African Cape South Coast is bordered by one of the broadest continental shelves in Africa. The Agulhas Bank, inshore shelf and presently exposed coastal plain make up the Palaeo-Agulhas Plain (PAP), though our area of study extends beyond this limit and as far inland as the first mountain belt. Quaternary sea levels have been significantly lower than at present for ∼90% of the Pleistocene, exposing a terrestrial ecosystem on what is now the submerged shelf. The presently drowned component makes up 94% of the total area of the PAP. Past work has hypothesised a contrast in character of this submerged landscape when compared to the subaerial environment. Here, we assimilate newly-acquired geophysical and geological datasets to produce geological- and soil maps from the Last Glacial Maximum on a scale of 1:750,000, covering an area of ∼55,000 km. Three broad geomorphic zones are defined, including the Western section from Cape Agulhas to Cape Infanta, the Central section from Cape Infanta to Knysna and the Eastern section extending eastward of Knysna. We demonstrate that Mesozoic sedimentary deposits crop out near the surface on this current-swept shelf and soils derived from siltstone and shale bedrock are prominent when the coast is up to 64 km distant from the modern shoreline at its maximum point. Beyond this, weathered limestone dominates the substrate sequences on the Agulhas Bank. We show that the submerged landscape was a unique terrestrial environment and that there is no exact modern-day analogue in the region other than a small (∼70 km〈sup〉2〈/sup〉) area located at the edge of the Agulhas Plain near Cape Agulhas, and map major contrasts in the geological, topographic and edaphic nature of the landscape from the onshore to the offshore. The expansion of this plain is coupled with exaggerated floodplains, meandering shallowly incised rivers and wetlands. The submerged shelf is dominated by fertile soils compared to the dissected onshore belt, and extensive calcareous dunefields extending up to 10 km inland from their associated palaeoshorelines covered much of the emergent shelf. Sedimentary bedforms may have obstructed or slowed drainage as suggested by leached palaeosols and carbonate mixing observed in petrographic thin sections and grain mounts. The data show a low-relief “plains” landscape, which contrasts strongly to the topographically complex contemporary coastal foreland.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 219〈/p〉 〈p〉Author(s): Brian M. Chase, Arnoud Boom, Andrew S. Carr, Manuel Chevalier, Lynne J. Quick, G. Anthony Verboom, Paula J. Reimer〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Cape Floristic Region (CFR) is one of the world's major biodiversity hotspots, and much work has gone into identifying the drivers of this diversity. Considered regionally in the context of Quaternary climate change, climate stability is generally accepted as being one of the major factors promoting the abundance of species now present in the CFR. However, little direct evidence is available from the region, and responses to changes in global boundary conditions have been difficult to assess. In this paper, we present new high-resolution stable isotope data from Pakhuis Pass, in the species-rich western CFR, and contextualise our findings through comparison with other records from the region. Combined, they indicate clear, coherent changes in regional hydroclimate, which we relate to broader forcing mechanisms. However, while these climate change events share similar timings (indicating shared macro-scale drivers), the responses are distinct between sites, in some cases expressing opposing trends over very short spatial gradients (〈50 km). We describe the evolution of these trends, and propose that while long-term (10〈sup〉5〈/sup〉 yr) general climatic stability may have fostered high diversity in the region through low extinction rates, the strong, abrupt changes in hydroclimate gradients observed in our records may have driven a form of allopatric speciation pump, promoting the diversification of plant lineages through the periodic isolation and recombination of plant populations.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 220〈/p〉 〈p〉Author(s): Andrea Columbu, Christoph Spötl, Jo De Waele, Tsai-Luen Yu, Chuan-Chou Shen, Fernando Gázquez〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Here we present the first record of Marine Isotope Stage (MIS) 7 from Sardinia, based on a U-Th-dated speleothem from Crovassa Azzurra cave, which also grew during MIS 5. Carbonate precipitation was continuous during MIS 7, while two multi-millennial hiatuses interrupted growth during MIS 5. These hiatuses occurred during times of unstable climate, but local karst-specific conditions are considered to have played an important role as well. δ〈sup〉13〈/sup〉C values mostly reflect soil bioproductivity and vegetation density. During less humid periods these values reflect bedrock δ〈sup〉13〈/sup〉C values, because of a semi-closed system and/or sulphuric acid-driven bedrock dissolution. δ〈sup〉18〈/sup〉O changes were governed by the interplay of rainfall amount and moisture source. Disentangling these two effects was possible by comparing δ〈sup〉13〈/sup〉C and δ〈sup〉18〈/sup〉O values, whereby both isotopes co-vary during periods when δ〈sup〉18〈/sup〉O was dominated by the amount effect. Changes in the relative proportion of Atlantic and Mediterranean moisture sources was the main control on δ〈sup〉18〈/sup〉O at times when δ〈sup〉18〈/sup〉O was decoupled from δ〈sup〉13〈/sup〉C.〈/p〉 〈p〉δ〈sup〉18〈/sup〉O variations during MIS 5 are synchronous with Greenland stadials (GS) and interstadials (GI) GS 26, GI 25, GI-GS 22, GI-GS 21. With the exception of GS 22, these climate oscillations did not affect soil bioproductivity, and δ〈sup〉18〈/sup〉O mirrors the relative proportion of Atlantic and Mediterranean moisture sources. GS 22 was a prominent arid period in Sardinia, in accordance with other regional palaeoclimate archives.〈/p〉 〈p〉High soil bioproductivity is indicated by δ〈sup〉13〈/sup〉C values for MIS 7e and MIS 7c-a; the latter interval was characterized by a 30 kyr-long time span of warm and humid conditions in Sardinia. Soil bioproductivity decreased markedly during MIS 7d and the climate became drier. The latter period, also constrained by δ〈sup〉18〈/sup〉O data, lasted significantly shorter in Sardinia than in central Europe.〈/p〉 〈p〉As indicated by changes in δ〈sup〉13〈/sup〉C and δ〈sup〉18〈/sup〉O relationships, variations in moisture source are also recorded for MIS 7, with Mediterranean-dominated rainfall during MIS 7e and 7c followed by a shift toward Atlantic-dominated rainfall.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 1 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Zenobia Jacobs, Brian G. Jones, Hayley C. Cawthra, Christopher S. Henshilwood, Richard G. Roberts〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The site of Blombos Cave (BBC) is well known for archaeological remains that have advanced our understanding of the development of modern human behaviour during the Middle Stone Age (MSA). Occupation of the cave occurred against a backdrop of landscape-scale environmental and sedimentary processes that provide the broader context for finer-scale interpretations of the site-formation history and archaeological patterns detected in the cave deposits. Aeolian and palaeosol sequences are abundant in the vicinity of BBC and these provide a partial view of the past landscapes available to the inhabitants of the cave. An important extension to the palaeo-landscape around BBC currently lies submerged on the Agulhas Bank, as sea levels were lower than at present for the entire period of human occupation of BBC. In this paper, we revisit the optically stimulated luminescence (OSL) chronology for the full sequence of sediment deposition inside BBC, increasing the number of dated samples to a total of 40 and revising the period of MSA occupation to between 97.7 ± 7.6 and 71.0 ± 5.7 ka (uncertainties at 95.4% probability). We describe the geological successions at four main areas around BBC, estimate the time of sediment deposition using OSL, and describe and interpret three seismic profiles on the Agulhas Bank, offshore of BBC. By correlating these onshore and offshore geological sequences with the sedimentary deposits inside BBC, we place the archaeological record within a landscape-scale chrono-stratigraphic framework to examine how environmental changes may have regulated the presence or absence of humans in the cave and surrounding terrain between about 100 and 70 ka.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 220〈/p〉 〈p〉Author(s): Demet Biltekin, Francesc Burjachs, Josep Vallverdú, Warren D. Sharp, Regina Mertz-Kraus, M. Gema Chacón, Palmira Saladié, James L. Bischoff, Eudald Carbonell〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study addresses the pollen record of Abric Romaní archaeological site and the climate evolution of the last interglacial and glacial stadials in the Iberian Peninsula. The new pollen record spans the interval from 110,000 to 55,000 years ago. In general, the glacial/stadial vegetation is characterized by a steppe and herbaceous communities indicating dry and cold climatic conditions, whereas the vegetation optimum of past interglacials can be described as pine-oaks with mediterranean forest indicating milder and moister climatic conditions. During the first half of the MIS 5a and the MIS 5c, the region was warmer, which is characterized by temperate forests. However, the existence of 〈em〉Artemisia〈/em〉 steppes during the second part of the MIS 5a indicates that the degree of continentality can be related to the low winter temperatures and precipitation. During MIS 4, a colder and dryer climate enabled the development of open vegetation (dominated by 〈em〉Artemisia〈/em〉 with Poaceae and other Asteraceae) around the study site.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 220〈/p〉 〈p〉Author(s): Peter D. Strand, Joerg M. Schaefer, Aaron E. Putnam, George H. Denton, David J.A. Barrell, Tobias N.B. Koffman, Roseanne Schwartz〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We undertook geomorphological mapping in conjunction with 〈sup〉10〈/sup〉Be surface-exposure dating in a previously unstudied sector of the left-lateral moraine sequence of the ice-age Pukaki glacier in the Southern Alps of New Zealand. The mapping and dating approach enabled the identification of six distinct moraine belts that were formed during maxima of glacier extent during the last glaciation. The chronology implies that ice recession occurred during Northern Hemisphere Heinrich stadials, while expansion occurred between Heinrich stadials. The ages of the moraine belts identified here are 44,000 ± 1000 yrs; 41,800 ± 1100 yrs; 36,450 ± 940 yrs 26,730 ± 740 yrs; 20,030 ± 460 yrs; and 18,000 ± 400 yrs. This moraine chronology is consistent with previous dating results from other sectors of the Pukaki moraine sequence, except that the c. 44,000 yr old moraine belt has not previously been detected elsewhere in the Pukaki moraines. Collectively with previously published 〈sup〉10〈/sup〉Be chronologies from the Pukaki glacier, and the adjacent Ohau glacier valley, the results demonstrate that there were several millennial-scale episodes of ice advance to full-glacial extent, and subsequent ice recession, during Marine Isotope Stages 3 and 2. This millennial-scale pulsebeat of oscillations of the Pukaki and Ohau glaciers in sympathy with the North Atlantic Heinrich episodes is further emphasized by rapid ice recession in the Southern Alps early in the last glacial termination, coeval with the onset of Heinrich stadial 1 (HS 1) in the Northern Hemisphere. That this pattern is widespread in mid-latitudes of the Southern Hemisphere is highlighted by similar chronologies of glacier variation for Andean ice lobes in the Chilean Lake District of South America.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 220〈/p〉 〈p〉Author(s): William E. Banks, Pascal Bertran, Sylvain Ducasse, Laurent Klaric, Philippe Lanos, Caroline Renard, Miriam Mesa〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Investigations of chronology play a key role in the majority of archaeological research endeavors and are particularly pertinent to examinations of culture-environment relationships, especially during periods characterized by rapid and marked climatic variability and environmental reorganization. Rigorous evaluations of available data and robust methods are required if one wishes to reconstruct reliable chronologies, and this is especially the case when examining periods that are associated with a relatively few radiometric measurements. Such is the case for the Upper Paleolithic archaeological record documented in present-day France from 32,000 to 21,000 calibrated years BP. We take into account critically examined radiocarbon measurements from contextually secure archaeological contexts and employ a recently-developed method of Hierarchical Bayesian Modeling to reconstruct the chronology of archaeological cultures from the Middle Gravettian to the Badegoulian. The calculated chronological intervals for each typo-technologically defined culture phase are compared to the Greenland ice core climatic record and a terrestrial paleoenvironmental record from Bergsee Lake (Southern Germany)—itself expressed in calendar years calculated with the same calibration curve employed in our age model—thereby permitting each archaeological culture to be correlated accurately with documented paleoclimatic variability.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 220〈/p〉 〈p〉Author(s): Scott A. Reynhout, Esteban A. Sagredo, Michael R. Kaplan, Juan Carlos Aravena, Mateo A. Martini, Patricio I. Moreno, Maisa Rojas, Roseanne Schwartz, Joerg M. Schaefer〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Alpine glaciers are sensitive indicators of changes in climate, and their ubiquity in mountainous regions make them valuable proxies for terrestrial climate reconstructions worldwide. However, the timing and extent of glacier change across the South American mid-latitudes through the Holocene are still poorly constrained relative to their counterparts in the Northern Hemisphere. Here we report a new 〈sup〉10〈/sup〉Be surface exposure-based chronology of moraines recording a series of progressively less-extensive glacier advances of Glaciar Torre (Argentina, 49.3°S/73.0°W) since the Last Glacial Maximum, with expansions culminating at 17,600 ± 900, 13,500 ± 500, 9700 ± 400, 6900 ± 200, 6100 ± 300, 4500 ± 200, and 530 ± 60 yr BP. The declining magnitude of Holocene glacier expansions parallels a gradual rise in local summer insolation intensity during the Holocene, while individual advances occurred during inferred negative Southern Annular Mode (SAM)-like states at centennial to millennial timescales. These observations suggest that (i) summer insolation intensity modulated antiphased trends in glacier extent in the polar hemispheres during the Holocene, and that (ii) centennial-scale ‘SAM-like’ temperature and precipitation anomalies paced glacier fluctuations throughout Patagonia. Given the persistence of the inferred ’SAM-like’ anomalies throughout the Holocene, the modern measured trend towards positive SAM index conditions could mark the onset of a fundamental shift in the climate of the Southern Hemisphere midlatitudes that warrants consideration in projections of future climate.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0277379119300745-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 16 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Robert A. Dull, John R. Southon, Steffen Kutterolf, Kevin J. Anchukaitis, Armin Freundt, David B. Wahl, Payson Sheets, Paul Amaroli, Walter Hernandez, Michael C. Wiemann, Clive Oppenheimer〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ilopango volcano (El Salvador) erupted violently during the Maya Classic Period (250–900 CE) in a densely-populated and intensively-cultivated region of the southern Maya realm, causing regional abandonment of an area covering more than 20,000 km〈sup〉2〈/sup〉. However, neither the regional nor global impacts of the Tierra Blanca Joven (TBJ) eruption in Mesoamerica have been well appraised due to limitations in available volcanological, chronological, and archaeological observations. Here we present new evidence of the age, magnitude and sulfur release of the TBJ eruption, establishing it as one of the two hitherto unidentified volcanic triggers of a period of stratospheric aerosol loading that profoundly impacted Northern Hemisphere climate and society between circa 536 and 550 CE. Our chronology is derived from 100 new radiocarbon measurements performed on three subfossil tree trunks enveloped in proximal TBJ pyroclastic deposits. We also reassess the eruption magnitude using terrestrial (El Salvador, Guatemala, Honduras) and near-shore marine TBJ tephra deposit thickness measurements. Together, our new constraints on the age, eruption size (43.6 km〈sup〉3〈/sup〉 Dense Rock Equivalent of magma, magnitude = 7.0) and sulfur yield (∼9–90 Tg), along with Ilopango's latitude (13.7° N), squarely frame the TBJ as the major climate-forcing eruption of 539 or 540 CE identified in bipolar ice cores and sourced to the tropics. In addition to deepening appreciation of the TBJ eruption's impacts in Mesoamerica, linking it to the major Northern Hemisphere climatic downturn of the mid-6th century CE offers another piece in the puzzle of understanding Eurasian history of the period.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0277379119301465-fx1.jpg" width="156" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 221〈/p〉 〈p〉Author(s): Carl Regnéll, Jan Mangerud, John Inge Svendsen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉We present geomorphological evidence of large, previously undocumented, early Holocene ice-dammed lakes in the Scandinavian Mountains of northwestern Sweden. The lakes extents indicate that the last remnants of the Scandinavian Ice Sheet were located east of the mountain range. Some early pioneering works have presented similar reconstructions, whereas more recently published reconstructions place the last ice remnants in the high mountains of Sarek.〈/p〉 〈p〉Using high-resolution airborne LiDAR data we have mapped a large number of hitherto undocumented shorelines in some of the main valleys within the northern Scandinavian mountain range. Our results indicate that a larger system of ice-dammed lakes existed in this region than previously thought. The lakes were dammed between the main water divide to the west and the retreating ice sheet margin to the east. The shorelines dip towards the northwest with gradients ranging from 0.5 to 0.4 m/km, from the oldest to the youngest. Further, we have compiled Lateglacial and Holocene shoreline data along the Norwegian coast and from within the Baltic Sea basin and reconstructed the isostatic uplift along a 1400 km long northwest-southeast transect from the Norwegian Sea to Lake Ladoga. By comparing the measured ice-dammed lake shoreline gradients to the dated marine shorelines, we infer that the lakes may have existed for several centuries following 10.2 cal ka BP. We also describe large deposits and extensive erosive features, which demonstrate that a catastrophic glacial lake outburst flood (GLOF) took place eastward along the Pite River Valley. Based on cross-cutting relations to raised shorelines developed in the early Holocene Ancylus Lake (Baltic Sea basin) we conclude that the flood and thus the final phase of deglaciation took place within the time interval 10.3–9.9 cal ka BP.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 5 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Willem G.M. van der Bilt, Andreas Born, Kristian A. Haaga〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The timing and causes of Common Era (CE) glacier growth in the Arctic Atlantic region remain elusive. There is mounting evidence of advances that predate the Little Ice Age (1250–1850 CE); this challenges the view that 13th century volcanic eruptions triggered change by spurring sea-ice expansion. Recent climate model simulations indicate this response does not require external forcing under contemporaneous (Pre-Industrial) boundary conditions. Here, we try to reconcile these new insights by combining regional proxy evidence of glacier and sea-ice change with a climate model experiment. Collated recently published reconstructions demonstrate that regional climate shifted towards a colder mean state around 650–950 CE, a period marked by low radiative forcing. Unforced model simulations reproduce the time-transgressive evolution of this response, which emerged east of Greenland and progressed towards Svalbard. The inferred pattern is associated with sea-ice feedbacks, triggered by stochastic atmospheric cooling. We argue that this mechanism may explain the timing and pattern of CE glacier growth in the region.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 28 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Mariana Nabais, João Zilhão〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Optimal foraging theory and diet breadth models often place large mammals in top-ranking positions due to their high-energy return. However, mass collection of small prey can result in comparable return rates, and dietary diversity is nutritionally beneficial on its own right. A growing body of evidence recovered from several sites in the Mediterranean Basin confirms Neanderthal use of small size prey. Slow-moving, tortoises are an easy catch, and human collection and consumption is demonstrated by taphonomic analysis. In Portugal, two key Middle Palaeolithic cave sites, Gruta da Oliveira and Gruta da Figueira Brava, provide pertinent evidence. Based on an improved osteometric method, in which long bone measurements are standardised and analysed together using the Logarithmic Size Index (LSI), it is possible to better gauge the contribution of tortoises to the diet and the human impact on the species’ populations. At inland Gruta da Oliveira, a tendency towards the massive collection of tortoises, affecting the local population more severely, is apparent. At coastal Gruta da Figueira Brava, the data suggest opportunistic collection upon encounter, possibly due to the availability of a more diverse range of resources.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 211〈/p〉 〈p〉Author(s): Benjamin M.P. Chandler, Clare M. Boston, Sven Lukas〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Considerable research has been conducted in Scotland to reconstruct Younger Dryas glaciers and palaeoclimatic conditions, but our understanding remains incomplete. In this contribution, we examine the Gaick, a dissected plateau that extends over ∼520 km〈sup〉2〈/sup〉 in the Central Grampians, Scotland. The extent and style of Younger Dryas glaciation in the Gaick has been repeatedly contested, although a model of extensive plateau icefield glaciation has become generally accepted. This is despite well-documented issues with key elements of the plateau icefield reconstruction. We synthesise the results of recent geomorphological mapping in the Gaick and recognise a distinct morphostratigraphic signature in the upper parts of the western catchments. This differs markedly from sediment-landform associations in other parts of the area, and we argue this provides a strong indication of spatially-restricted Younger Dryas (∼12.9–11.7 ka) glaciation in the Gaick. Our interpretation is independently supported by glacierisation threshold analysis, which implies that the eastern Gaick was unable to nourish Younger Dryas ice. We therefore contest the accepted paradigm of extensive Younger Dryas glaciation in this area. Based on the geomorphological evidence and glacier surface profile modelling, we reconstruct a ∼42 km〈sup〉2〈/sup〉 plateau icefield that yields an equilibrium line altitude of 751 ± 46 m. Using this value, a sea-level precipitation value of 826 ± 331 mm a〈sup〉−1〈/sup〉 is inferred for the Younger Dryas, which suggests considerably drier conditions than at present. Using recalculated glacier-derived precipitation estimates from Scotland, we present regional climate analysis that corroborates arguments for a strong west-east precipitation gradient across Scotland.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 27 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Jordi Rosell, Ruth Blasco〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Fire represented a real revolution in human lifestyles, transforming the way food was processed and leading to a new way of organising settlements and interacting socially. Yet, it is one of the most debated and controversial issues in the field of Palaeolithic archaeology. The scientific community generally proposes that the regular and controlled use of fire occurred from 400 to 300 ka onward, and that the archaeological signal became well established in sites younger than 100 ka. Thus, the chronological range between 400 and 300 ka is crucial to exploring how this phenomenon and the associated behavioural changes occurred. Here, we examine the zooarchaeological signature this process left on the faunal record, including procurement techniques and animal processing (e.g., roasting). The data are compared to information from sites without fire that are framed within the same chronological period. Our objective is to collect zooarchaeological data on the process of dependence on fire as a central element in the new human mode of adaptation.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 211〈/p〉 〈p〉Author(s): Claire Archer, Paula Noble, Michael R. Rosen, Leonardo Sagnotti, Fabio Florindo, Scott Mensing, Gianluca Piovesan, Alessandro Maria Michetti〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Small lakes in low relief areas are atypical candidates for studies on paleoseismicity, but their sediments can contain seismically induced event layers (seismites) generated through strong ground shaking, sediment transport, hydrological reorganization and/or changes in groundwater chemistry and flow. Lakes Lungo and Ripasottile are shallow lakes (〈10 m deep) located in the tectonically active Rieti Basin in the central Apennines, Italy, where strong normal faulting earthquakes (Mw 6.5 to 7.0) regularly occur. Sediment cores from these lakes provide paleoseismic indicators for the past ∼1000 years. Sedimentological and geochemical analysis reveals four event layers identified in both lakes that correspond with documented large-scale earthquakes in 1298, 1349, 1639, and 1703 AD. Chronological correlation between earthquakes and paleoseismic features is reliable because of the resolution of sediment dating available for the studied cores. The common physical structure is a physically homogenous bed (homogenite) of re-suspended sediment consisting of a denser, high magnetic susceptibility (κ) clastic base, with organic matter concentrated above. Co-seismic to post-seismic chemical signatures are associated with some event layers and may represent abrupt or transient shifts to a groundwater-dominated system, or permanent changes in groundwater flow and/or spring discharge. Excursions in δ〈sup〉13〈/sup〉C〈sub〉org〈/sub〉 may represent disruptions or changes in carbon source. Not all event layers show the same features, a result attributed to differences in seismic processes as well as the lake attributes, and anthropogenic modification. The observations made here may provide a new means of detecting paleoseismicity and may be applied to other low relief lakes in seismically active areas.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 211〈/p〉 〈p〉Author(s): Camille Bréant, Amaëlle Landais, Anaïs Orsi, Patricia Martinerie, Thomas Extier, Frédéric Prié, Barbara Stenni, Jean Jouzel, Valérie Masson-Delmotte, Markus Leuenberger〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Each glacial – interglacial transition of the Quaternary occurs in a different orbital context leading to various timing for the deglaciation and sequence of high vs low latitudes events. Termination 3, 250 kyears before present (ka), is an unusual deglaciation in the context of the last 9 deglaciations recorded in the old EPICA Dome C (EDC) Antarctic ice core: it exhibits a three-phase sequence, two warming phases separated by a small cooling, the last phase suggesting a particularly rapid temperature increase. We present here new high resolution δ〈sup〉15〈/sup〉N and deuterium excess (d-excess) data from the EDC ice core to provide a detailed temperature change estimate during this termination. Then, we combined the δD and δ〈sup〉18〈/sup〉O to discuss the relationship between high and low latitude changes through the d-excess. We also provide the high vs low latitude sequence of events over this deglaciation without chronological uncertainty using low latitude ice core proxies. In agreement with previous studies based on speleothem analyses, we show that the first phase of Termination 3 (256–249 ka) is associated with small Heinrich like events linked to changes in ITCZ position, monsoon activity and teleconnections with Antarctica. In a context of minimum Northern Hemisphere insolation, this leads to a rather strong Antarctic warming, as observed in the δ〈sup〉15〈/sup〉N record in contrast to the relatively small δD increase. The second warming phase occurs during the rise of the Northern hemisphere insolation, with a large Heinrich like event leading to the characteristic Antarctic warming observed in the δ〈sup〉15〈/sup〉N and δD increase as for the more recent terminations.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 211〈/p〉 〈p〉Author(s): Zachary C. Dunseth, Daniel Fuks, Dafna Langgut, Ehud Weiss, Yoel Melamed, Don H. Butler, Xin Yan, Elisabetta Boaretto, Yotam Tepper, Guy Bar-Oz, Ruth Shahack-Gross〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This article presents a systematic methodological comparison of three archaeobotanical proxies (phytoliths, pollen and seeds) applied to an assemblage of dung pellets and corresponding archaeological refuse deposits from Early Islamic contexts at the site of Shivta. We set out with three main methodological questions: one, to evaluate the relative input of botanical remains from dung in refuse assemblages; two, to evaluate each archaeobotanical dataset and to test whether they are comparable, complementary or contradictory in their interpretations from dung; and three, infer herding practices at the site during the Early Islamic period. Our findings show that ovicaprine dung accumulated in Early Islamic Shivta during at least two periods: mid-7th–mid-8th centuries CE, and late-8th–mid-10th centuries CE. Methodologically, we see incomplete and incompatible reconstructions arise when each method is considered alone, with each proxy possessing its own advantages and limitations. Specifically, the amount of preserved seeds in dung pellets is low, which restricts statistical analysis and tends to emphasize small or hard-coated seeds and vegetation fruiting season; yet this method has the highest taxonomic power; pollen preserves only in uncharred pellets, emphasizes the flowering season and has an intermediate taxonomic value; phytoliths have the lowest taxonomic value yet complete the picture of livestock feeding habits by identifying leaf and stem remains, some from domestic cereals, which went unnoticed in both seed and pollen analyses. The combined archaeobotanical reconstruction from samples of the mid-7th–mid-8th centuries suggests that spring-time herding at Shivta was based on free-grazing of wild vegetation, supplemented by chaff and/or hay from domestic cereals. For the late-8th–mid-10th century samples, phytolith and pollen reconstruction indicates autumn-winter free-grazing with no evidence of foddering. Unlike the dung pellets, macrobotanical remains in the refuse deposits included domestic as well as wild taxa, the former mainly food plants that serve for human consumption. Plant remains in these refuse deposits originate primarily from domestic trash and are only partially composed of dung remains. The significance of this study is not only in its general methodological contribution to archaeobotany, but also to lasting discussions regarding the contribution of dung remains to archaeological deposits used for seed, pollen and phytolith analyses. We offer here a strong method for determining whether deposits derive from dung alone, are mixed, or absolutely do not contain dung. This has important ramifications for archaeological interpretation.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 211〈/p〉 〈p〉Author(s): Paul Szpak, James M. Savelle, James Conolly, Michael P. Richards〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Environmental change in the Arctic has been a primary topic of interest in recent years, particularly as it relates to the consequences of anthropogenic climate change. Sea ice is of particular importance in this context, both in terms of the effects of climate change in the Arctic, but also globally. Most studies examining the responses of various components of the biosphere to warming temperatures necessarily have a short temporal perspective. The purpose of this study was to use stable isotopes to examine long-term variation (c. 4000–500 yr BP) in the ecology of a ubiquitous Arctic marine mammal (the ringed seal, 〈em〉Pusa hispida〈/em〉) that is intimately linked to sea ice. We present 〈em〉δ〈/em〉〈sup〉13〈/sup〉C and 〈em〉δ〈/em〉〈sup〉15〈/sup〉N values for ringed seal bone collagen from archaeological sites in the central Canadian Arctic Archipelago as well as 61 new AMS 〈sup〉14〈/sup〉C dates from these sites. Ringed seal 〈em〉δ〈/em〉〈sup〉13〈/sup〉C values increased between the earliest sites in our study, Early Pre-Dorset (c. 4000 cal yr BP), through to the Late Dorset period (c. 800 cal yr BP) suggesting increasing primary productivity derived from sea ice relative to phytoplankton over this period and an overall cooling trend. Between the Late Dorset (1500–700 yr BP) and Thule (c. 700−500 yr BP) periods there was an abrupt decline in the contribution of sea ice algae to higher trophic levels, consistent with reduced sea ice extent and increased open water conditions. These data demonstrate the potential of using marine mammals from archaeological sites to reconstruct the changing importance of sea ice to food webs over time and offer insight into the consequences of climatic variation at higher trophic levels, which is difficult if not impossible to obtain with other proxy records.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 28 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Richard J. Payne, Fin Ring-Hrubesh, Graham Rush, Thomas J. Sloan, Chris D. Evans, Dmitri Mauquoy〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Falkland Islands in the South Atlantic Ocean contain extensive peatlands at the edge of their global climatic envelope, but the long-term carbon dynamics of these sites is poorly quantified. We present new data for ten sites, compile previously-published data and produce a new synthesis. Many peatlands in the Falkland Islands developed notably early, with a fifth of basal 〈sup〉14〈/sup〉C dates pre-Holocene. Falkland Islands peats have high ash content, high carbon content and high bulk density compared to global norms. In many sites carbon accumulation rates are extremely low, which may partly relate to low average rainfall, or to carbon loss through burning and aeolian processes. However, in coastal Tussac peatlands carbon accumulation can be extremely rapid. Our re-analysis of published data from Beauchene Island, the southernmost of the Falkland Islands, yields an exceptional long-term apparent carbon accumulation rate of 139 g C m〈sup〉−2〈/sup〉 yr〈sup〉−1〈/sup〉, to our knowledge the highest recorded for any global peatland. This high accumulation might relate to the combination of a long growing-season and marine nutrient inputs. Given extensive coverage and carbon-dense peats the carbon stock of Falkland Islands peatlands is clearly considerable but robust quantification will require the development of a reliable peat map. Falkland Island peatlands challenge many standard assumptions and deserve more detailed study.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 211〈/p〉 〈p〉Author(s): Thomas M. Urban, Jeffrey T. Rasic, Claire Alix, Douglas D. Anderson, Linda Chisholm, Robert W. Jacob, Sturt W. Manning, Owen K. Mason, Andrew H. Tremayne, Dale Vinson〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Magnetic survey methods have recently shown tremendous potential for the detection of archaeological hearths in Eastern Beringia, ranging from intermittent open-air camp fires to larger heat intensive activity areas. Here we present an overview of the method along with eight supporting case studies from seven U.S. National Park Service units in the U.S. state of Alaska, covering diverse geographic settings and time-periods. Together, these case studies demonstrate the capabilities of magnetic detection instruments in various modes of operation for finding datable archaeological deposits that span the breadth of known human occupation of this region. The examples range from the simplest use of the magnetometer as a single sensor reconnaissance instrument in a “search mode”, to use as a gradiometer in conjunction with other geophysical methods such as ground-penetrating radar, to record precise measurements and inform nuanced interpretations. Examples presented here range from the terminal Pleistocene to historic periods, spanning 12,000 years of human activity in Eastern Beringia, and encompassing the arrival, emergence, and expansion of multiple human groups or cultural traditions in the New World.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 211〈/p〉 〈p〉Author(s): Christophe Colin, Nadine Tisnérat-Laborde, Furu Mienis, Tim Collart, Edwige Pons-Branchu, Quentin Dubois-Dauphin, Norbert Frank, Arnaud Dapoigny, Mohamed Ayache, Didier Swingedouw, Jean-Claude Dutay, Frédérique Eynaud, Maxime Debret, Dominique Blamart, Eric Douville〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Variations in North Atlantic Ocean mid-depth circulation during the Holocene are poorly understood. It is believed that they had a significant influence on the properties of water entering the Nordic Sea by redistributing heat and freshwater, potentially affecting deep-water formation and climate. To improve our knowledge of the NE Atlantic mid-depth circulation, radiocarbon and neodymium isotope analyses have been then carried out on precisely dated (U-Th) 〈em〉L. pertusa〈/em〉 and 〈em〉M. oculata〈/em〉 coral fragments from two sediment cores taken at ∼750 m water depth on the SW Rockall Trough margin. Cold-water coral (CWC) εNd values vary between −12.2 ± 0.3 and −16.6 ± 0.4 and result from variable contributions of unradiogenic mid-depth subpolar gyre (mid-SPG) water (∼-15) and more radiogenic Eastern North Atlantic Water (ENAW) (∼-11) which is transported northward to the Rockall Trough by boundary currents along the European margin. Increased coral εNd reflects a westward contraction of the mid-SPG water and a higher proportion of ENAW. The mid-Holocene (from 8.8 to 6.8 ka BP) is marked by unradiogenic coral εNd (from −16.6 ± 0.4 to −14.6 ± 0.5) indicating a greater eastward extension of the mid-SPG. This is followed by a shift from 6.8 to 5 ka BP toward more radiogenic εNd values (from −15.4 ± 0.3 to −13.3 ± 0.2) suggesting a westward contraction of the mid-SPG and a higher proportion of ENAW. The mid-Holocene long-term change in εNd is characterized by millennial variations of up to 2.5 epsilon units well marked during the Late Holocene, indicating that eastward extension of the mid-SPG coeval with warm periods in northern Europe (e.g. the Medieval Climatic Anomaly and the Roman Warm Period). Most of the CWC-derived Δ〈sup〉14〈/sup〉C values match the global ocean values indicating that the water masses bathing the corals were generally well ventilated; the exceptions are a few short intervals of eastward extension of the mid-SPG, which are characterized by lower Δ〈sup〉14〈/sup〉C during the late Holocene. We propose that these minor Δ〈sup〉14〈/sup〉C fluctuations in the Rockall Trough may be related to local changes in the mixed layer depth or to variability in the advection of water from the Labrador Sea where deep convection gives rise to thermocline waters that are relatively depleted in terms of Δ〈sup〉14〈/sup〉C.〈/p〉 〈p〉The eastward extension of the mid-SPG between 8.8 and 6.8 ka BP is associated with the Holocene climatic optimum, concurrent with a maximum strength of the Iceland-Scotland Overflow Water (ISOW), which is indicative of an increase in the Atlantic Meridional Overturning Circulation (AMOC). This period is followed by a transition in the North Atlantic circulation, which occurred around 6.8 ka BP, and coincides with the onset of Labrador Sea Water formation, a decrease of the ISOW strength and a contraction of the mid-SPG leading to a greater intrusion of saline subtropical water into the subpolar Atlantic.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 205〈/p〉 〈p〉Author(s): Lee B. Corbett, Paul R. Bierman, Stephen F. Wright, Jeremy D. Shakun, P. Thompson Davis, Brent M. Goehring, Christopher T. Halsted, Alexandria J. Koester, Marc W. Caffee, Susan R. Zimmerman〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Constraining glacial history and process on Mt Mansfield, the highest peak in Vermont (1339 m a.s.l.), provides insight into how the Laurentide Ice Sheet shaped the underlying landscape, when latest Pleistocene ice retreated, and how upland and lowland glacial histories relate. Here, we quantify 〈em〉in situ〈/em〉 cosmogenic 〈sup〉10〈/sup〉Be in 20 bedrock and boulder surfaces, as well as 〈em〉in situ〈/em〉 cosmogenic 〈sup〉14〈/sup〉C in three of those surfaces, to assess subglacial erosion and exposure history. Isotopic concentrations indicate that Mt. Mansfield's lower elevations (∼400–1200 m a.s.l.) were deeply eroded by at least several meters during the last glaciation and then deglaciated rapidly; 〈sup〉10〈/sup〉Be ages across this elevation span are indistinguishable and average 13.9 ± 0.6 ka (n = 15), suggesting that 800 m of ice thinning occurred within at most about a millennium. Conversely, the higher elevations (〉1200 m a.s.l.) preserve a more complex geomorphic history. Mt. Mansfield's summit surfaces contain 〈sup〉10〈/sup〉Be from previous periods of exposure, indicating that the mountaintop landscapes were likely preserved beneath cold-based, weakly-erosive glacial ice. Exposure ages from the shorter-lived isotope, 〈sup〉14〈/sup〉C, are younger (9.7 and 11.7 ka), suggesting that Mt. Mansfield's summit was covered until the early Holocene, perhaps by snowfields, ice carapaces, and/or till. Our findings, in context of previous work, suggest that thinning Laurentide ice flowed through the valleys for at most hundreds of years following deglaciation of the uplands, but that the summit remained shielded by ice or sediment for millennia after the valleys became ice-free.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 205〈/p〉 〈p〉Author(s): G.M. Cárdenes-Sandí, C.R. Shadik, A. Correa-Metrio, W.D. Gosling, R. Cheddadi, M.B. Bush〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Last Interglacial (c. 128,000 to 115,000 years ago) was the last time when global temperatures may have been higher than those of the Holocene, but little is known about vegetation change or paleoclimate during that period in Central America. A new fossil pollen record from the lowland setting of El Valle, Panama, spanned the period from 137,000 to 98,000 years ago. We used multivariate analysis of modern and fossil pollen samples to provide the first regional quantification of Last Interglacial temperature and precipitation change and found mean annual temperatures were c. 1–2 °C warmer than modern, while precipitation was mostly similar to modern. The montane genus 〈em〉Quercus〈/em〉 was intermittently present throughout the interglacial period, leading to the inference that this dispersal-limited taxon was surviving in microrefugia. Both charcoal and the early successional genus 〈em〉Cecropia〈/em〉 were noticeably rare in the last interglacial compared with the Holocene. The modern absence of 〈em〉Quercus〈/em〉 from Central Panama does not appear to be the product of interglacial warming, but rather a result of dry conditions in the late Holocene and human activity. It is suggested that humans greatly increased fire frequency, thereby favoring 〈em〉Cecropia〈/em〉 and eliminating 〈em〉Quercus〈/em〉 from the lower portion of its elevational range.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 223〈/p〉 〈p〉Author(s): Lorelei Curtin, William J. D'Andrea, Nicholas Balascio, Genevieve Pugsley, Gregory de Wet, Raymond Bradley〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Last Interglacial period (LIG) is Earth's most recent globally warm period and is analogous in some ways to projected future global warming. However, questions remain regarding the state of the climate during the LIG in the North Atlantic, a region that is extremely sensitive to changes in oceanic and atmospheric circulation. Here, we present hydrogen and carbon isotope (δD and δ〈sup〉13〈/sup〉C) records from a suite of plant wax biomarkers preserved in Holocene and LIG lacustrine sediments from the North Atlantic Faroe Islands and interpret them as qualitative proxies for temperature and hydroclimate variability. These data are used to directly compare LIG and Holocene climate using the same proxy approaches from the same terrestrial location. Measuring multiple isotopes on multiple types of waxes elucidates the sources of homologous plant waxes. We deduce that the δD values of long-chain 〈em〉n〈/em〉-alkanes (C〈sub〉27〈/sub〉–C〈sub〉33〈/sub〉) and mid-chain 〈em〉n〈/em〉-alkanes (C〈sub〉23〈/sub〉–C〈sub〉25〈/sub〉) in these sedimentary archives reflect leaf water and lake water δD values, respectively, while the δD values for both long-chain (C〈sub〉28〈/sub〉–C〈sub〉30〈/sub〉) and mid-chain n-alkanoic acids (C〈sub〉24〈/sub〉–C〈sub〉26〈/sub〉) primarily represent lake water δD values. Plant wax-inferred δD values of precipitation during the early Holocene (10,100 to 8,200  cal  yr BP) are ∼35‰ more positive than late Holocene values, and decline over the Holocene. δD-inferred hydrologic change and δ〈sup〉13〈/sup〉C -inferred plant water use efficiency both indicate that the Faroe Islands became drier throughout the Holocene. Comparison with measurements from LIG plant waxes indicates that late LIG in the Faroe Islands was hydrologically similar to the early-to mid-Holocene (8,200 to 4,000  cal  yr BP), with enriched precipitation isotopes and reduced evapotranspiration indicating a warmer, wetter environment.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 223〈/p〉 〈p〉Author(s): E.G. Sessford, M.F. Jensen, A.A. Tisserand, F. Muschitiello, T. Dokken, K.H. Nisancioglu, E. Jansen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Rapid warmings epitomize the Dansgaard-Oeschger events that are recorded in Greenland ice cores and imprinted in ocean sediment cores. While the abrupt climate changes appear connected to perturbations in sea ice and ocean circulation, it is unclear how the water masses within the Nordic Seas responded and were influenced by the inflowing Atlantic Water in the absence or presence of sea ice. High resolution reconstructions of benthic Mg/Ca, together with stable isotopes of carbon and oxygen (δ〈sup〉13〈/sup〉C and δ〈sup〉18〈/sup〉O), show a recurring warming (2.5° ± 0.5 °C) occurring consistently at the inflow and outflow of the Nordic Seas at intermediate depths down to 1500 m during Greenland Stadials 9–6. Using idealized numerical simulations with an eddy-resolving ocean model we investigate the impact of an isolating sea ice cover and freshwater lid in the Nordic Seas. With the presence of an extensive sea ice cover, the warm Atlantic Water entering the Nordic Seas in the east, retains its heat as it exits in the west. The depth of the recirculating warm Atlantic Water increases when including an external freshwater source at the surface of the Nordic Seas. These findings support the view that cold stadials are accompanied by pervasive intermediate water warming across the Nordic Seas. Given the current rates of Arctic sea ice loss, these results provide a potential mechanism for water-column destabilization and inception of abrupt climate change.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 222〈/p〉 〈p〉Author(s): Laura Arppe, Juha A. Karhu, Sergey Vartanyan, Dorothée G. Drucker, Heli Etu-Sihvola, Hervé Bocherens〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The world's last population of woolly mammoths (〈em〉Mammuthus primigenius〈/em〉) lived on Wrangel Island persisting well into the Holocene, going extinct at ca. 4000 cal BP. According to the frequency of radiocarbon dated mammoth remains from the island, the extinction appears fairly abrupt. This study investigates the ecology of the Wrangel Island mammoth population by means of carbon, nitrogen and sulfur isotope analyses. We report new isotope data on 77 radiocarbon dated mammoth specimens from Wrangel Island and Siberia, and evaluate them in relation to previously published isotope data for Pleistocene mammoths from Beringia and lower latitude Eurasia, and the other insular Holocene mammoth population from St. Paul Island. Contrary to prior suggestions of gradual habitat deterioration, the nitrogen isotope values of the Wrangel Island mammoths do not support a decline in forage quality/quantity, and are in fact very similar to their north Beringian forebears right to the end. However, compared to Siberian mammoths, those from Wrangel Island show a difference in their energy economy as judged by the carbon isotope values of structural carbonate, possibly representing a lower need of adaptive strategies for survival in extreme cold. Increased mid-Holocene weathering of rock formations in the central mountains is suggested by sulfur isotope values. Scenarios related to water quality problems stemming from increased weathering, and a possibility of a catastrophic starvation event as a cause of, or contributing factor in their demise are discussed.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 222〈/p〉 〈p〉Author(s): Denizcan Köseoğlu, Simon T. Belt, Jochen Knies〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Advanced knowledge of spatio-temporal constraints on the Barents Sea Ice Sheet during the late Weichselian glaciation overshadows relatively limited understanding of seasonal sea ice (experiencing an annual advance-retreat cycle) and primary productivity trends accompanying massive, abrupt climate changes during glacial-deglacial cycles. Such paleo-reconstructions are crucial prerequisites for improved comprehension and prediction of current and future climate change. Here, we investigate sea ice and phytoplankton biomarker distributions in a Barents Sea sediment core covering ca. 25.8–15.4 cal kyr BP to elucidate abrupt shifts of spring–summer sea ice concentrations and relative sympagic–pelagic productivity trends at the southwestern continental slope. Despite significant presence of seasonal sea ice, the Last Glacial Maximum (LGM) and initial shelf edge deglaciation (SEDG) at the core site are characterised by occurrence of productive coastal polynya adjacent to the maximum ice sheet extent. The onset of perennial (i.e. multi-year) ice cover and near-zero productivity during Heinrich Stadial 1 (HS1; ca. 18.0–16.3 cal kyr BP) accompanies significant meltwater fluxes from ice sheet debuttressing and the consequent stagnation of thermohaline circulation. Rapid sea ice retreat and unprecedented pelagic productivity observed after 16.3 cal kyr BP coincides with areal ice sheet deglaciation and is potentially linked to the release of sub-surface heat and nutrient reservoirs, together with reinvigorated deep water circulation following millennial heating of the deep ocean during HS1. We find that a multivariate fingerprinting approach involving assessment of both downcore and surface biomarker distributions is able to distinguish relative ice-algal and pelagic diatom productivity driven by sea ice dynamics.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 222〈/p〉 〈p〉Author(s): Přemysl Bobek, Helena Svobodová-Svitavská, Petr Pokorný, Pavel Šamonil, Petr Kuneš, Radka Kozáková, Vojtěch Abraham, Tereza Klinerová, Markéta Gabriela Švarcová, Eva Jamrichová, Eva Krauseová, Jan Wild〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Fire occurrence is driven by a complex interplay between vegetation, climatic, landform and human factors making it challenging to separate the individual effect of each variable. Here we present a reconstruction of the Holocene biomass burning history of two regions located in the Central European temperate zone that differ in the timing of the Middle Holocene expansion of broadleaf-dominated forest communities. This allowed us to investigate the effect of biotic changes on past fire activity. Multiple-site charcoal accumulation records were used to estimate regional-scale trends in biomass burning and to compare them with major trajectories of vegetation development. Extensive 〈sup〉14〈/sup〉C-dated soil charcoal records collected within both regions were amalgamated using a cumulative probability function to identify a stand-scale proxy of past fire occurrence. Our results suggest that rising vegetation productivity driven by rapid Early Holocene climate amelioration enhanced biomass burning. The increased fire activity during this period was driven by both a drier- and warmer-than-present climate and easily flammable fuels produced by conifer-dominated vegetation. We identified an inhibiting effect of the concomitant 〈em〉Fagus sylvatica〈/em〉 expansion on levels of biomass burning that occurred asynchronously between our mountain and mid-elevation sandstone regions 6500 cal yr BP and 4900 cal yr BP, respectively. The amount of compositional change in plant communities was more related to the transformation of major vegetation types than to fluctuations in fire activity levels. The divergent timing of the fire decline in response to the 〈em〉Fagus sylvatica〈/em〉 expansion implies biotic control over biomass burning that is independent of a direct climatic influence.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 222〈/p〉 〈p〉Author(s): B.L. Hall, T.V. Lowell, G.R.M. Bromley, G.H. Denton, A.E. Putnam〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Records of past variability afford context for evaluating present-day glacier behavior and for testing hypotheses of climate change. Here, we use 69 radiocarbon dates of wood and other organic materials in association with glacial deposits to document the behavior of Ventisqueros Marinelli and Brooks in Cordillera Darwin over the past ∼17,000 years. Recession from the last glacial maximum was early, with most occurring prior to 17,000 yr BP. Any glacial resurgence during the Antarctic Cold Reversal must have terminated within the bounds of Holocene ice fluctuations. By early Holocene time, Ventisquero Marinelli had retreated such that it was no more extensive than it was in AD 1992. We identify several subsequent glacier readvances, but also note long periods of restricted ice extent, particularly in the mid-Holocene. There were times when Holocene glaciers must have been smaller than at present. Our new record from Marinelli shows similarities to other reconstructions of Holocene glacier variation from southern South America, such as at Mt. Sarmiento and the South Patagonian Icefield, suggesting an underlying climate signal. The overall implication is of substantial early Holocene deglaciation followed by repeated advances interspersed with periods of recession when ice extent was smaller than at present. This general pattern of glacier behavior appears to differ from that of New Zealand's Southern Alps and points to the value of a geographic spread of datasets to elucidate the pattern of Southern Hemisphere climate during the Holocene.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 13 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Simen Oestmo, Marco A. Janssen, Hayley C. Cawthra〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Palaeo-Agulhas Plain (PAP), when exposed, presented Middle Stone Age (MSA) foragers at Pinnacle Point (PP) on the South Coast of South Africa with new sources of raw materials to make stone tools. Sea-level fluctuations and the changing size of the Paleo-Agulhas Plain throughout the Pleistocene PP record ∼165 ka to 50 ka would have altered the availability of different resources, thus potentially forcing new raw material procurement strategies. The relative frequencies of raw material throughout the PP sequence shows that frequencies of raw material types did change, especially after 90 ka. What caused these changing frequencies is debated and centers on whether targeted procurement of specific raw materials was the cause, or if simple raw material availability and abundance due to the changing environmental context in conjunction with opportunistic procurement drove such shifts. The application of a neutral model of stone raw material procurement presented here evaluates whether random walk in the region surrounding the PP site during different coastline configurations (Marine Isotope Stage 6, 5, and 4) explains the observed shifts in raw material usage. Put differently, did opportunistic acquisition of raw materials during random walk in these different environments cause the observed raw material pattern? Model simulations and a sensitivity analysis provide no convincing evidence that observed raw material frequencies at PP resulted from opportunistic acquisition during random walk.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 226〈/p〉 〈p〉Author(s): Luca Capraro, Fabio Tateo, Patrizia Ferretti, Eliana Fornaciari, Patrizia Macrì, Daniele Scarponi, Nereo Preto, Feng Xian, Xianghui Kong, Xingjun Xie〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The 〈sup〉10〈/sup〉Be/〈sup〉9〈/sup〉Be ratio is commonly employed as a tool for establishing the stratigraphic position of paleomagnetic excursions and reversals whenever the traditional paleomagnetic approach fails to provide conclusive results. In particular, it is held that 〈sup〉10〈/sup〉Be production rates in the atmosphere depend on the strength of the Earth’s magnetic field, and the fallout and deposition of cosmogenic beryllium at the surface happen on a very short time scale. However, investigations performed on terrestrial and marine successions demonstrate that the 〈sup〉10〈/sup〉Be record and the paleomagnetic signal are often asynchronous. Mechanisms that control the conveyance and deposition of cosmogenic 〈sup〉10〈/sup〉Be to the seafloor are still ambiguous and poorly documented. Here, we discuss the dynamics of 〈sup〉10〈/sup〉Be in a central Mediterranean marginal marine depositional scenario characterized by a pervasive terrigenous influx. Our data show that a very close correlation exists between 〈sup〉10〈/sup〉Be concentrations and the local proxy of rainfall rates and regimes (pollen), indicating that a considerable 〈sup〉10〈/sup〉Be transport from the mainland may occur in response to the remobilization of terrestrial reservoirs during periods of increased runoff. Superimposed is a dynamic oceanographic setting that further controls the preservation potential of 〈sup〉10〈/sup〉Be at the bottom, in terms of changing water chemistry and/or composition of the sedimentary flux to the seafloor. Results of our investigation suggest that, in particular environmental and depositional settings, the interplay between climate, terrigenous yield and oceanography may jeopardize the sedimentary depiction of the meteoric 〈sup〉10〈/sup〉Be contribution, thus challenging the use of 〈sup〉10〈/sup〉Be for tracking the stratigraphic position of geomagnetic reversals.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 226〈/p〉 〈p〉Author(s): E. Rehn, A. Rehn, A. Possemiers〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Fire is a significant natural and cultural phenomenon, affecting spatial scales from local to global, and is represented in most palaeoenvironmental records by fossil charcoal. Analysis is resource-intensive and requires high-level expert knowledge. This study is a preliminary investigation of the application of artificial neural networks to fossil charcoal particle analysis, utilizing a U-Net variant for charcoal particle identification and VGG for particle classification by morphology. Both neural networks performed well, reaching ∼96% accuracy for particle identification and ∼75% accuracy for classification. Future work will include expansion of the training dataset, including total number of particles and number of sites. The development and application of this automated system will increase the efficiency of fossil charcoal analysis.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 226〈/p〉 〈p〉Author(s): Juan M. Lora, Daniel E. Ibarra〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉While the climate evolution of North America during the last deglaciation has received considerable attention, few detailed model–data comparisons of the deglacial hydroclimate have been conducted at the continental scale. Here we use a transient climate simulation of the last deglaciation and a synthesis of hydroclimate proxies from across the continent to broadly assess the moisture budget and its evolution, including the primary components and mechanisms for changes, and evaluate the level of agreement between model and data in order to inform areas of major discrepancy for attention in future work. At the broadest scale, the simulation indicates that North America was wetter than modern through much of the last deglaciation, with the exception of the Pacific Northwest. This was principally due to increased moisture convergence by the mean flow over the west of the continent, and by transient eddies over the east. We find that the simulation demonstrates considerable skill in comparison to proxy records in the coastal Southwest and Pacific Northwest, with limited success in other regions. The highest disagreement occurs in the North-central region, where the model and data disagree on the sign of changes. In addition, we find that the areas of agreement coincide with regions whose hydroclimate is dominated by winter precipitation, while regions of disagreement are those where summer precipitation is predominant, and where the model suggests dynamical changes are important. These results illustrate the impact of the ice sheet on the atmospheric dynamics, and therefore the importance of its accurate reconstruction, as well as that of model resolution. Our analysis and synthesis provide context for future transient climate simulations, and suggest numerous areas of priority for future research.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 225〈/p〉 〈p〉Author(s): Nicolò Ardenghi, Andreas Mulch, Andreas Koutsodendris, Jörg Pross, Ansgar Kahmen, Eva M. Niedermeyer〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The Mediterranean region is highly sensitive to climate change, particularly with regard to warming and increasing aridity. Understanding its past climate history during periods similar to the Holocene is key to understand the long-term dynamics that accompany anthropogenic climate change. Marine Isotope Stage (MIS) 11 (ca. 424–367 ka BP) is considered one of the best Holocene analogues. Despite detailed insight from Atlantic marine records and European continental records, MIS 11 temperature and rainfall evolution in the Mediterranean remains poorly understood.〈/p〉 〈p〉We present a detailed record of MIS 11–10 climate change at Tenaghi Philippon, a telmatic peatland in NE Greece. We use microbial membrane lipids (brGDGTs), the δD of 〈em〉n〈/em〉-C〈sub〉29〈/sub〉 (δD〈sub〉wax〈/sub〉) and distribution of 〈em〉n〈/em〉-alkanes derived from plant leaf waxes, and levoglucosan concentrations to reconstruct changes in temperature, rainfall sources and vegetation burning. Glacial-interglacial temperature patterns indicate strong Atlantic influence in the Eastern Mediterranean region.〈/p〉 〈p〉Low δD〈sub〉wax〈/sub〉 values and high temperatures indicate a predominance of Atlantic-sourced winter precipitation during MIS 11, and vice versa during MIS 10. The latter is attributed to a suppression of the Mediterranean storm track, probably due to a persistent high-pressure cell over most of the European continent, mainly in response to an extended ice cover during the glacial. The levoglucosan record is consistent with rapid change to drier conditions and increased vegetation burning from MIS 11 to 10. Millennial-scale oscillations allow to characterise cooling episodes previously recorded at other sites, with conditions of decreased winter precipitation, while suggesting increased seasonality during the interglacial optimum.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 224〈/p〉 〈p〉Author(s): Mark D. Johnson, Per O. Wedel, Ívar Benediktsson, Anna Lenninger〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉New highway exposures and drilling reveal the stratigraphy and structure of the Middle Swedish end-moraine zone west of Billingen, Sweden. The material in the end moraines is primarily glaciomarine clay of Younger Dryas age that was deposited as varved clay in front of the retreating glacier and then pushed glaciotectonically to form push moraines during minor ice-margin oscillations during overall retreat during the Younger Dryas cold event. The moraines are composed of deformed and remobilized clay with some clayey diamicton and penecontemporaneously deposited and deformed sand. Between the moraines lie ‘intermoraine flats,’ composed of undeformed varved clay of Younger Dryas age and surface sands of Younger Dryas to early Holocene age. Based on estimations of moraine volume, sedimentation rate and ice-margin retreat rates, we calculate the overall ice-margin retreat and end-moraine construction to span 350–800 years within the Younger Dryas. Because the number of moraines in the Middle Swedish end-moraine zone varies across Sweden, we regard the individual oscillations west of Billingen to be driven by local physical and glaciologic factors rather than ice-sheet wide climate drivers. The study area is also the location of the early and final drainages of the Baltic Ice Lake. The final drainage of the Baltic Ice Lake took place several decades after the youngest moraine was formed. We consider it likely that the earlier, Allerød drainage of the Baltic Ice Lake (BIL) also took place at Billingen, despite the lack of clear local stratigraphic evidence. However, based on our model, a retreat driven solely by climate would not have exposed the outlet at Billingen, and we propose a dynamic break-up of the ice-margin likely centered on Valle Härad that was driven by the head difference between the BIL and the sea.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 225〈/p〉 〈p〉Author(s): Jamie M. McFarlin, Yarrow Axford, Andrew L. Masterson, Magdalena R. Osburn〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Sedimentary plant wax distributions and isotopic compositions are powerful, widely applied paleoenvironmental proxies. However, there is conflicting evidence on the behavior of these proxies at high-latitude sites, where extreme climate and light conditions may uniquely influence plant physiology and growth. Here, we present modern sedimentary 〈em〉n〈/em〉-alkane and 〈em〉n〈/em〉-alkanoic acid abundances and compound-specific (δ〈sup〉2〈/sup〉H and δ〈sup〉13〈/sup〉C) isotope values from a 22-lake transect extending from northwest to southernmost Greenland, covering a large latitudinal and climatic gradient. Sedimentary plant waxes are similar in abundance and carbon isotopic composition across the transect, suggesting no major differences in biologic sources. There are strong correlations (r = 0.8–0.9) between δ〈sup〉2〈/sup〉H values of many long-chain sedimentary waxes and those of modelled precipitation, with 〈em〉n〈/em〉-alkanes more tightly correlated to precipitation than 〈em〉n〈/em〉-alkanoic acids. Data presented here also demonstrate that δ〈sup〉2〈/sup〉H values of mid-chain sedimentary waxes do not strongly correlate to the δ〈sup〉2〈/sup〉H values of lake water when it decouples isotopically from precipitation (i.e. in glacier-fed and evaporatively-enriched lakes). This calls into question the common interpretation that mid-chain sedimentary waxes can be ascribed to aquatic plants. We contextualize our Greenland data with an updated global dataset of δ〈sup〉2〈/sup〉H values of modern sedimentary waxes and precipitation. This update adds 100 + lakes from recently published literature to the seminal review presented by Sachse et al. (2012). This large new compilation suggests a global average apparent fractionation including Arctic data between 〈em〉n-〈/em〉C〈sub〉28〈/sub〉 alkanoic acids and annual precipitation (ε〈sub〉C28/ANN〈/sub〉) of −99‰, and between 〈em〉n-〈/em〉C〈sub〉29〈/sub〉 alkanes and annual precipitation (ε〈sub〉C29/ANN〈/sub〉) of −121‰. The latter value is remarkably consistent with the value first reported by Sachse et al. (2012).〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 225〈/p〉 〈p〉Author(s): Rachael S. Avery, Alan E.S. Kemp, Jonathan M. Bull, Richard B. Pearce, Mark E. Vardy, J. James Fielding, Carol J. Cotterill〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Annually laminated sediments (varves) provide excellent temporal resolution to study rapid environmental change, but are rare in the early part of the Last Termination (∼19–∼11.7 ka BP). We present a new 〉400 varve year (vyr) varve sequence in two floating parts from Windermere, a lake at the southern margin of the mountains of northwest England. This sequence records the final retreat of the Windermere glacier at the southern edge of the Lake District Ice Cap during the transition from Heinrich Stadial 1 (∼18–∼14.7 ka BP) into the Lateglacial Interstadial (∼14.7–∼12.9 ka BP).〈/p〉 〈p〉Laminated sediments from four lake cores from Windermere's northern and southern basins were investigated and shown to be varved. These sequences are integrated with seismic reflection evidence to reconstruct south-to-north deglaciation. Seismic and sedimentological evidence is consistent with gradual stepped ice retreat along the entire southern basin and into the northern basin between 255 and 700 vyr prior to the appearance of significant biota in the sediment that heralded the Lateglacial Interstadial, and had retreated past a recessional moraine (RM8) in the northern basin by 121 vyr prior to the interstadial. The Lateglacial Interstadial age of this biota-bearing unit was confirmed by 〈sup〉14〈/sup〉C-dating, including one date from the northernmost core of ∼13.5 cal ka BP. A change in mineralogy in all four cores as the glacier retreated north of the Dent Group (the northernmost source of calcareous bedrock) and a decrease in coarse grains in the varves shows that the ice had retreated along the entire North Basin at ∼70 vyr prior to the Lateglacial Interstadial. The estimated retreat rate is 70–114 m yr〈sup〉−1〈/sup〉 although buried De Geer moraines, if annual, may indicate retreat of 120 m yr〈sup〉−1〈/sup〉 with a ≥3 year stillstand at a recessional moraine halfway along the basin. The glacier then retreated north of the lake basin, becoming land-terminating and retreating at 92.5–49 m yr〈sup〉−1〈/sup〉.〈/p〉 〈p〉The northernmost core has a varve sequence ending at least 111 vyr after the other core chronologies, due to the increased proximity to remnant ice in the catchment uplands into the early Lateglacial Interstadial. We show that almost all of the glacier retreat in the Windermere catchment occurred before the abrupt warming at the onset of the Lateglacial Interstadial, in keeping with similar findings from around the Irish Sea Basin, and suggesting a similar retreat timescale for other radial valley glaciers of the Lake District Ice Cap. The seismic and core evidence also show the potential for a much longer varve chronology extending at least 400 and potentially over 1000 vyr further back into Heinrich Stadial 1 (18–14.7 ka BP), suggesting that glacier retreat in the Windermere valley initiated at least before 15.5 ka BP and perhaps 16 ka BP.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 16 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): H.C. Cawthra, P. Frenzel, A. Hahn, J.S. Compton, L. Gander, M. Zabel〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The inner to mid continental shelf of the Agulhas Bank, which forms part of the Palaeo-Agulhas Plain, is scattered with Pleistocene deposits. Their wide lateral extension is the expression of a flat underlying substrate, availability of accommodation space, and depositional processes in response to glacio-eustatic sea-level change. We present seismic sub-bottom profiles up to 30 m deep, sediment cores up to 5 m in length and Pleistocene deposits that date back to Marine Isotope Stage (MIS) 7 from the inner to mid shelf between the Breede River in the West and Plettenberg Bay in the East. Radiocarbon and optically stimulated luminescence dates are integrated with microfossil analysis into a seismic stratigraphic model comprised of twenty Quaternary facies units within two depositional sequences bounded by shelf-wide unconformities. Sequence Boundary 1 (SB1) corresponds to the erosional unconformity with bedrock and SB2 to the MIS 2 glacial lowstand. Incised palaeo-river channels are associated with both sequence boundaries and cored deposits also mapped seismically from estuarine, lacustrine and fluvial systems are grouped to represent the lower floodplain. The most pervasive stratigraphic pattern in these shelf deposits is made up of the depositional sequence remnant of the Falling Stage Systems Tract (FSST) forced regression from MIS 5e–2. The other dominant stratigraphic group is the Transgressive Systems Tract (TST) associated with the Post-glacial Marine Transgression. The TST makes up an almost equal proportion of deposits in both sequences in the sedimentological record as the FSST, despite the shorter temporal span of the TST. A Wave Ravinement Surface marks the rise in sea level from the Last Glacial Maximum in a landward direction.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 224〈/p〉 〈p〉Author(s): R. Hamilton, J. Stevenson, B. Li, Satria Bijaksana〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The tropical forests of Sulawesi represent some of the most diverse, biogeographically significant ecosystems globally. However, long-term ecological data for the region are scarce, making it difficult to predict vegetation response to future climatic and anthropogenic drivers of change. This is problematic as gauging the acclimation thresholds of forests within tropical Asia has been identified as an IPCC policy imperative.〈/p〉 〈p〉This study uses palynological and geochemical analysis of sediments from a tectonic basin – Lake Lantoa – to reconstruct the hydroclimatic, fire, and tropical rainforest dynamics of south Sulawesi over 16,000 years, and reveal the response of lowland ultramafic forest to large-scale environmental change. Our results show that the Late Pleistocene was characterised by a drier, more seasonal climate and persistent fire in the landscape. These conditions supported a slightly open, 〈em〉Gymnostoma〈/em〉-rich, semi-seasonal forest, and constrained the available habitat range for hydrophilic tropical conifers. Increased effective moisture in the Holocene, interpreted from the onset of periodic lake stratification under deeper conditions, appears to have precluded forest burning, and facilitated the expansion of a lowland ultramafic rainforest and upland tropical coniferous forest. An increase in garden/secondary forest taxa and ground ferns from ∼2 cal kyrs BP implies increased human management of the landscape. While these data highlight the compositional dynamism of lowland forest in Wallacea to seasonality, fire, and reduced precipitation, they demonstrate biome-scale resilience to glacial-scale environmental change. This contrasts with interpretations of forest sensitivity to climatic change drawn from analysis of leaf wax isotopes from adjacent lake basins, highlighting the value of adopting multi-proxy, taxonomically high-resolution techniques for reconstructing floristic histories.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 224〈/p〉 〈p〉Author(s): J. Blinkhorn, P. Ajithprasad, A. Mukherjee, P. Kumar, J.A. Durcan, P. Roberts〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉South Asia has a rich Palaeolithic heritage, and chronological resolution for this record has substantially improved over the past decade as a result of focused, interdisciplinary research at a number of key sites. Expanding the spatial diversity of dated Palaeolithic sites in South Asia grows increasingly important to examine how patterns of change through time vary within and between the region’s diverse habitats. Critically, alternate models of modern human dispersals into South Asia highlight the significance of either coastal or continental routes of dispersal, but currently no coastal Palaeolithic sites directly dating to the timeframe of human expansions are known. Our previous research in Kachchh was the first study to clearly identify the presence of Palaeolithic sites in Late Pleistocene landscapes in close proximity to the Indian Ocean coastline. Here, we present the first results of surface survey and test excavation at the site of Sandhav (Kachchh, India), approximately 25 km from the modern shoreline. We characterise the geomorphology of the landscape, highlighting multiple phases of alluvial aggradation and post-depositional carbonate formation, associated with Palaeolithic artefacts. To date, excavations have tested the uppermost Pleistocene deposit, yielding a small collection of fresh Middle Palaeolithic artefacts associated with a luminescence age dating to the first half of MIS 5 (∼114 ka), which provides a minimum age for Late Acheulean artefacts in underlying units. We discuss our findings in the context of debates surrounding the timing, lithic technologies, and ecologies associated with the expansions of modern humans into South Asia.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 225〈/p〉 〈p〉Author(s): Elizabeth Morosi, Martin Ubilla〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The first analyses of carbon and oxygen stable isotopes (〈em〉δ〈/em〉〈sup〉13〈/sup〉C, 〈em〉δ〈/em〉〈sup〉18〈/sup〉O) on horses of late Pleistocene beds, between 50 and 30 kyr B.P., at mid-latitudes of South America (northern Uruguay), are reported here. Isotopic analyses on 〈em〉Equus neogeus〈/em〉 and 〈em〉Hippidion principale〈/em〉 were made on tooth enamel, considering the Suess Effect. Isotopic values have been used as indicators of diets and environmental conditions, alongside with Hypsodonty Index, to pinpoint specific feeding strategies as grazer or browser. 〈em〉E. neogeus〈/em〉 was a mixed-grazer that fed mostly on C〈sub〉3〈/sub〉 grass in open wooded areas and grasslands with a variable proportion of C〈sub〉4〈/sub〉 grass in the diet. 〈em〉H. principale〈/em〉 was a mixed feeder with preference for open canopy wooded floor C〈sub〉3〈/sub〉 grass and plants. These results could explain the co-occurrence of both taxa that evolved a combination of feeding and habitat preferences that resulted in niche differentiation. The isotopic data supports the diversity of habitats previously proposed by other authors and corroborate the environmental context associated to the mammal assemblage in late Pleistocene at these latitudes of South America. Juveniles show 〈em〉δ〈/em〉〈sup〉13〈/sup〉C depletion and 〈em〉δ〈/em〉〈sup〉18〈/sup〉O enrichment related to adults. This shift could be explained by maternal effect, owing to gestation and lactation (depleted 〈em〉δ〈/em〉〈sup〉13〈/sup〉C and enriched 〈em〉δ〈/em〉〈sup〉18〈/sup〉O). The later because breast milk is significantly enriched in 〈em〉δ〈/em〉〈sup〉18〈/sup〉O in comparison to drinking water and also is not fractionated in the same way as plant-derived carbon.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 225〈/p〉 〈p〉Author(s): Rory Connolly, Margarita Jambrina-Enríquez, Antonio V. Herrera-Herrera, Paloma Vidal-Matutano, Ana Fagoaga, Rafael Marquina-Blasco, María Dolores Marin-Monfort, Francisco Javier Ruiz-Sánchez, César Laplana, Salvador Bailon, Leopoldo Pérez, Lucia Leierer, Cristo M. Hernández, Bertila Galván, Carolina Mallol〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper presents a multiproxy palaeoenvironmental study from Abric del Pastor (Alcoy, Spain), a rock shelter which has yielded evidence for Middle Palaeolithic human occupation. The sedimentary sequence has been analysed for lipid biomarker 〈em〉n〈/em〉-alkane abundances (ACL, CPI), compound specific leaf wax δ〈sup〉2〈/sup〉H and δ〈sup〉13〈/sup〉C, and bulk organic geochemistry (TOC, %N, %S), providing a record of past climate and local vegetation dynamics. Site formation processes have been reconstructed through the application of soil micromorphology. Analyses of anthracological, microvertebrate and macrofaunal assemblages from selected subunits are also presented here. Our data indicates that a variable climate marked by predominantly cold conditions persisted through most of the sequence and that Neanderthal occupations in stratigraphic unit IVd, assigned to MIS 4 or late MIS 5, occurred in a landscape setting characterised by a mosaic of biotopes. The presence of key resources inside the ravine where the site is located suggests that the occupation of the rock shelter may have been strategically motivated by a subsistence and mobility strategy which focused on zones of localised ecological resilience, such as intra-mountainous valleys or ravines, during periods of global or regional environmental downturn.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 225〈/p〉 〈p〉Author(s): Juan Marín, Antonio Rodríguez-Hidalgo, Josep Vallverdú, Bruno Gómez de Soler, Florent Rivals, José Ramón Rabuñal, Antonio Pineda, María Gema Chacón, Eudald Carbonell, Palmira Saladié〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Mobility strategies of Neanderthal groups are studied through the characterization and analysis of archaeological sites and traditionally compared to the types of settlements present-day hunter-gatherer groups, based on their mobility strategies. The faunal record of level P of Abric Romaní is a unique source of information for analysing the foraging behaviour developed by Neanderthals during MIS3. The assemblage is divided into two separate and well-defined sublevels: Pa and Pb. Through the taphonomic study of the remains and their spatial distribution, it was possible to define the characteristics of these human occupations. The analyses indicate that the assemblage was the result of at least two different types of occupations: 1) A transitory residential camp during short halts, focusing on the exploitation of red deer; 2) A hunting camp/intermediate butchering site for the specialized capture of horses. The presence of occupations focusing on the supply of specific resources is typical of collector groups. The results of the zooarchaeological study of level P characterize the Neanderthals of Abric Romaní as groups involved in a logistic mobility system, who moved throughout the territory depending on the availability of large ungulates.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 225〈/p〉 〈p〉Author(s): Roman Croitor, Montserrat Sanz, Joan Daura〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The article presents a description of cervid remains from the Middle Pleistocene Acheulean site of Gruta da Aroeira (= Galerias Pesadas) in central Portugal. The assemblage comprises the remains of four deer species: 〈em〉Cervus elaphus〈/em〉, 〈em〉Praedama〈/em〉 cf〈em〉. savini〈/em〉, 〈em〉Haploidoceros mediterraneus〈/em〉, and 〈em〉Dama〈/em〉 cf. 〈em〉vallonnetensis〈/em〉, making Gruta da Aroeira the first site in the Iberian Peninsula at which the genus 〈em〉Haploidoceros〈/em〉 has been documented in the Middle Pleistocene. Virtually all the cervids documented at the site demonstrate a degree of endemism, including evolutionary modifications of skull, antlers and dentition or a reduction in body size. The unusual richness of the cervid community at Gruta da Aroeira may be related to the specific biogeographic conditions of the Middle Pleistocene in Iberia. Thus, while the Iberian Peninsula’s geographical link with the temperate west Eurasian zone facilitated the dispersal of cervids of palearctic origin into Iberia, it impeded the dispersal of ruminants from warmer, more arid areas. The endemic character of the Middle Pleistocene cervids and the biodiversity of the Iberian Peninsula should shed some light on the paleobiogeography of Iberian hominins and their role in hominin hunting or their economic strategies.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 225〈/p〉 〈p〉Author(s): M.D. Marin-Monfort, S. García-Morato, R. Olucha, J. Yravedra, A. Piñeiro, I. Barja, P. Andrews, Y. Fernández-Jalvo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Small sized felids, such as wild and domestic cats, are one of the most common predators in the nature and in sites occupied by humans in archaeological and historical contexts. Wildcats have ingestion/digestion traits highly destructive for their prey, i.e.: teeth to chew causing extreme breakage, and digestion along the entire digestive tract with low pH gastric juices causing extreme bone corrosion. Small sized cats are also well known to play with the prey and select skeletal parts to ingest. The present study is focused on the taphonomic analysis of micromammal remains recovered from scats produced by European wildcats (〈em〉Felis silvestris silvestris〈/em〉) during several months and years. Excrements were collected from the Montes do Invernadeiro Natural Park (Galicia, Spain). Following the taphonomic methodological protocols, anatomical representation, bone breakage and degrees of digestive corrosion were evaluated. Results obtained from the skeletal representation indicate a high abundance of cranial skeleton and a high fracture pattern. Most dental elements show digestion, reaching extreme grades of corrosion, but the proportions of micromammal prey elements affected varies between taxonomic groups. The large sample size collected during 2 years, including different seasons, show no differences in either taxonomic composition or degree of digestion between the four seasons. The scat contents provide a basic and general pattern of alterations caused by carnivorous mammals on the bony elements of their prey. Some differences between felid predator species have also been observed, thus pointing out the necessity of more actualistic taphonomic analysis that will allow us to obtain a more accurate indication of modifications produced by small carnivorous mammals and specific differences.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 225〈/p〉 〈p〉Author(s): Jessica R. Rodysill, James M. Russell, Mathias Vuille, Sylvia Dee, Brent Lunghino, Satria Bijaksana〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Extreme precipitation events are one of the most consequential components of climate change for society. The El Niño-Southern Oscillation (ENSO) is the dominant mode of precipitation variability in the tropics and causes severe flooding and drought in many socioeconomically vulnerable regions. It remains unclear how tropical rainfall extremes and ENSO are changing in response to anthropogenic forcing, demanding that we investigate the relationships between precipitation, ENSO, and external forcing in the past. Lake sediment records have provided benchmark records of extreme flood events from the eastern tropical Pacific, where paleofloods have been interpreted to reflect El Niño events during the last millennium. However, the connections between flooding and ENSO variability in this region are uncertain, and the eastern Pacific can only capture precipitation events driven by El Niño, not La Niña. Thus, it is unclear how the ENSO system and tropical rainfall extremes have changed in the recent past. Here, we reconstruct flood events during the past millennium using a lake sediment record from East Java, Indonesia, which can provide insight into flooding driven by La Niña. We detect flood frequency variations in the western tropical Pacific that are highly coherent with records from the eastern part of the basin over the past millennium. Our findings demonstrate that heavy rainfall and flooding occurs more frequently on both sides of the tropical Pacific during periods of warmer Northern Hemisphere mean temperatures, implying that ENSO-driven rainfall extremes could intensify in the near future.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 225〈/p〉 〈p〉Author(s): Bas van Geel, Bram W. Langeveld, Dick Mol, Pim W.O. van der Knaap, Jacqueline F.N. van Leeuwen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Molars of eight large herbivore species (〈em〉Megaloceros giganteus, Cervus elaphus〈/em〉, 〈em〉Rangifer tarandus, Alces alces, Bison priscus, Ovibos moschatus, Coelodonta antiquitatis〈/em〉 and 〈em〉Stephanorhinus kirchbergensis〈/em〉) were collected 〈em〉ex situ〈/em〉 from Pleistocene and Holocene sands dredged in the North Sea, and from Dutch inland sites. Folds in many molars contained compacted masticated plant remains, and also microfossils. We identified pollen, spores, and non-pollen palynomorphs and discuss and interpret food preferences, represented flowering seasons, or parts of flowering seasons, and we discuss effects of changing vegetation composition in relation to climate and age of the molars, based on the pollen spectra. Various confounding factors have contributed to the recorded pollen composition, but nevertheless the pollen spectra show valuable aspects of vegetation composition, food choice, age, and landscapes, from subarctic open areas to interglacial forest. Ecological and statistical analysis of the results shows dietary differences between the mammal species analyzed.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 April 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 210〈/p〉 〈p〉Author(s): Brittany Marie Ward, Corinne I. Wong, Valdir F. Novello, David McGee, Roberto V. Santos, Lucas C.R. Silva, Francisco W. Cruz, Xianfeng Wang, R. Lawrence Edwards, Hai Cheng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Investigating controls on past variability of South American hydroclimate is critical to assessing its response to future warming scenarios. δ〈sup〉18〈/sup〉O records from South America offer insight into past variability of the South American Monsoon System (SAMS). The controls, however, on precipitation δ〈sup〉18〈/sup〉O values can be decoupled from precipitation amount at a given site and, thereby, limit local moisture condition reconstructions. Here we use a principal components analysis to assess the coherence of speleothem and lake core Holocene δ〈sup〉18〈/sup〉O records in tropical and subtropical South America to evaluate the extent to which δ〈sup〉18〈/sup〉O variability reflects changes in SAMS intensity at different sites across the region. The main mode of variability across Holocene δ〈sup〉18〈/sup〉O records (PC1) closely tracks austral summertime insolation, consistent with existing work. Sites towards the periphery of the continent are heavily weighted on PC1, whereas interior sites as not. Further δ〈sup〉18〈/sup〉O variability at interior sites bear little similarity to each other and implicate controls, beyond regional monsoon intensity, on these δ〈sup〉18〈/sup〉O records. Further, we develop speleothem 〈sup〉87〈/sup〉Sr/〈sup〉86〈/sup〉Sr records spanning the Holocene from Tamboril Cave (Brazilian Highlands), Paraíso Cave (eastern Amazon Basin), Jaraguá Cave (Mato Grosso do Sul Plateau), and Botuverá Cave (Atlantic coastal plain) to investigate coupling between reconstructed monsoon variability (reflected by PC1) and local moisture conditions (interpreted from 〈sup〉87〈/sup〉Sr/〈sup〉86〈/sup〉Sr records). We interpret speleothem 〈sup〉87〈/sup〉Sr/〈sup〉86〈/sup〉Sr variability as a proxy of local moisture conditions, reflecting the degree of water-rock interaction with the cave host rock as driven by variations in water residence time. Speleothem 〈sup〉87〈/sup〉Sr/〈sup〉86〈/sup〉Sr records from all the sites, except Botuverá cave, do not co-vary with PC1, suggesting that local moisture conditions do not necessarily follow variations in regional monsoon intensity at these interior sites. These speleothem 〈sup〉87〈/sup〉Sr/〈sup〉86〈/sup〉Sr records generally suggest dry mid-Holocene conditions relative to the early- and late-Holocene, consistent with interpretations of other paleo-moisture records in the region, but timing of wet-dry transitions varies between sites. These results highlight that controls, in addition to SAMS variability, might influence δ〈sup〉18〈/sup〉O variability. Further, our results suggest spatially variable local moisture conditions at interior sites that do not uniformly respond to regional monsoon intensity, and stress the need for δ〈sup〉18〈/sup〉O-independent reconstructions of moisture conditions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 April 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 210〈/p〉 〈p〉Author(s): Olivier Dézerald, Claudio Latorre, Julio L. Betancourt, Gabriel A. Brito Vera, Angélica L. González〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Evaluating the magnitude and direction of biases affecting the ecological information captured by death assemblages is an important prerequisite for understanding past, present, and future community-environment relationships. Here, we establish the ecological fidelity and spatiotemporal resolution of an overlooked source of fossil remains: the soil arthropod assemblages found in rodent middens (that span from the present to 〉44,420 cal yr BP) collected in the central Atacama Desert of northern Chile. We evaluated the “live-dead agreement” across four sources of soil arthropod data; two contemporary surveys of live communities (i.e., live), and two sources of death assemblages (i.e., dead). Although live-dead agreements and diversity indices are highly variable among samples (live and dead assemblages), our results consistently demonstrate that an average fossil midden (i) better captures the structure and composition of living communities than species richness 〈em〉per se〈/em〉; (ii) offers a spatially-resolved picture of those communities at local scales; and (iii) is only weakly affected by time-averaging. The fine spatiotemporal resolution of fossil midden records in the Atacama, and most likely other areas of the world where rodent middens occur offers ecological information on the structure and composition of fossil arthropod assemblages potentially over many thousands of years. This information is reliable enough to establish historical baselines before past and ongoing anthropogenic impacts.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 7 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Antonio Rosas, Markus Bastir, Jose Antonio Alarcón〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The long-standing debate around the origin and evolutionary mode of the Neandertal lineage is connected to the understanding of the large morphological diversity found in the European Middle Pleistocene Hominin (EMPH) samples. In practical terms, this problem can be approached through two questions: How many morphs can be distinguished in EMPH and how do they relate to the origin of Neandertals? These questions are addressed in this paper by means of geometric morphometric comparative analyses in combination with principles of craniofacial biology. We use the mandible as a model system because of its relative abundance in the fossil record, the presence of diagnostic features relevant to the process under analysis, and the key role played by some specimens. Among them, three samples are central in the debate: the Mauer mandible (as the holotype of 〈em〉Homo heidelbergensis〈/em〉), and the Arago and Atapuerca-SH samples. Our comparative analyses conclude that the Mauer and Arago samples derived from a single deme, and that Neandertal derived features that represent an incipient phase of the evolutionary process. The specimen AT-950 from the Atapuerca-SH sample has a number of structural similarities with Mauer, Arago and Montmaurin, which allows linking of this latter group with the complete Atapuerca-SH hypodigm. Consequently, all of these specimens are considered members of the Neandertal lineage. The fossil record illustrates a long evolutionary Neandertal lineage going back at least 0.6 million years. Against populational-based interpretations, we favor a structuralist approach and follow Enlow's counterpart growth analysis and compensatory growth mechanisms for interpretation of the EMPH diversity. In this framework, morphometric cranio-mandibular variation in hominin samples from the European Middle Pleistonece must be contemplated within the head form vertical variation pattern (e.g. vertical dolicho- and brachyfacial form spectrum) widespread in Hominoid species.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 April 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 210〈/p〉 〈p〉Author(s): Hiroyuki Takata, Hyung Jeek Kim, Hirofumi Asahi, Ellen Thomas, Chan Min Yoo, Sang Bum Chi, Boo-Keun Khim〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉We evaluated the response of Quaternary abyssal benthic foraminifera in cores PC5101 (2º00.86′N, 131º34.32′W) and PC5103 (6º00.10′N, 131º28.57′W) of the Central Equatorial Pacific Ocean to the environmental changes over the past ∼520 kyrs, focusing on the mid-Brunhes dissolution interval (∼533–191 ka). We used multi-dimensional scaling (MDS) to derive MDS axis 1, reflecting food supply from low (negative scores) to high (positive scores) amounts, and MDS axis 2, reflecting variability in the food supply. From ∼120 ka on, 〈em〉Epistominella exigua〈/em〉, an indicator of variable food supply, was more abundant in core PC5103 (∼6〈sup〉o〈/sup〉N) than in core PC5101 (∼2〈sup〉o〈/sup〉N), but this was reversed from ∼300 to 250 ka.〈/p〉 〈p〉In core PC5101, MDS axis 1 scores are negatively correlated to the biogenic opal mass accumulation rates (MAR) after 249.6 ka, i.e., lower food supply at higher opal-MAR. In contrast, MDS axis 1 scores are positively correlated to the CaCO〈sub〉3〈/sub〉-MAR from 520.8 to 331.2 ka. Both carbonate and opal skeletons might ballast particulate organic matter (POM) to enhance food supply to the benthos, but our data indicate that carbonate is more efficient and that changes in dominant ballasting of POM by different biominerals thus may have significantly affected the biological pump. During the transitional period (∼327.5–257.1 ka), ballasting of POM changed from control by calcareous plankton to control by siliceous plankton, with a transient period during which the latitudinal pattern of the Intertropical Convergence Zone was opposite to its modern pattern, with the more variable food supply at ∼ 6〈sup〉o〈/sup〉N.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 12 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): N. Marriner, D. Kaniewski, T. Gambin, B. Gambin, B. Vannière, C. Morhange, M. Djamali, K. Tachikawa, V. Robin, D. Rius, E. Bard〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Holocene colonisation of islands by humans has invariably led to deep-seated changes in landscape dynamics and ecology. In particular, burning was a management tool commonly used by prehistoric societies and it acted as a major driver of environmental change, particularly from the Neolithic onwards. To assess the role of early human impacts (e.g. livestock grazing, forest clearance and the cultivation of marginal land) in shaping “pristine” island landscapes, we here present a 350-year record of fire history and erosion from Malta, straddling the earliest peopling of the island. We show that recurrent anthropogenic burning related to Neolithic agro-pastoral practices began ∼7500 years ago, with well-defined fire-return intervals (FRI) of 15–20 years that engendered erosion and rapid environmental degradation. As early as the Neolithic, this study implies that, in sensitive insular contexts, just a few generations of human activities could rapidly degrade natural islandscapes.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 April 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 210〈/p〉 〈p〉Author(s): S. Ólafsdóttir, B.T. Reilly, J. Bakke, J.S. Stoner, M. Gjerde, W.G.M. van der Bilt〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We present a paleomagnetic study of two Holocene lake sediment sequences from Northwest Spitsbergen on Svalbard, Norway. Core HAP-212 from Lake Hajeren preserves a rare combination of a well-defined Characteristic Remanent Magnetization (ChRM) and robust age control defined by 21 terrestrial macrofossil-derived radiocarbon dates—providing a unique opportunity to assess the stratigraphic potential of High Arctic Holocene paleomagnetic secular variation (PSV) close to 80° N. Core AMP-112 from Hakluytvatnet, which is also well dated, is a poor magnetic recorder and cannot be used for geomagnetic reconstruction. Comparison of the HAP-212 PSV record with poorly dated regional records show similar directional features, suggesting that PSV can be used for chronological synchronization. Comparison of the HAP-212 PSV with well dated records ∼1800 km to the southwest and southeast show that these records are in-phase at millennial timescales, within dating and magnetic uncertainties, indicating that a consistent geomagnetic signal is recorded at these temporal and spatial scales. These findings support the notion that PSV, when optimally recorded, can be used to import chronologies from lower latitudes to the High Arctic, where low organic content, hard water effects, lack of datable material, and other difficulties often preclude more conventional radiocarbon dating.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 7 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Mohammed Allan, Adrien Deliège, Sophie Verheyden, Samuel Nicolay, Yves Quinif, Nathalie Fagel〈/p〉

Description: 〈p〉Publication date: 15 April 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 210〈/p〉 〈p〉Author(s): Flavia Strani, Daniel DeMiguel, David M. Alba, Salvador Moyà-Solà, Luca Bellucci, Raffaele Sardella, Joan Madurell-Malapeira〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Early-Middle Pleistocene Transition (EMPT) (ca. 1.4–0.4 Ma) represents a fundamental transformation in the Earth's climate state, starting at 1.4 Ma with a progressive increase in the amplitude of climatic oscillations and the establishment of strong asymmetry in global ice volume cycles. The progressive shift from a 41kyr–100kyr orbital rhythm was followed by the first major build-up of global ice volume during MIS 24-22, the so-called “0.9 Ma event”. The Vallparadís Section (Vallès-Penedès Basin, NE Iberian Peninsula) is one of the few Pleistocene series in Europe that spans the onset of the transition (from 1.2 to 0.6 Ma), thus representing a pivotal array of localities to investigate the effect of glacial dynamics on environmental conditions in Southern Europe. Here we inspect the effects of the EMPT on terrestrial ecosystems by examining the dietary adaptations (through dental meso- and microwear patterns) of fossil ungulates from the Vallparadís Section dated before and after the “0.9 Ma event”. Results show a steady presence of open grasslands before MIS 22 and more humid conditions at MIS 21. Both before and after MIS 22, a consistent presence of ungulates with long-term patterns that point to a grazing or grass-rich mixed feeding behaviour is observed, while noticeably, short-term patterns point to increased seasonality right after the “0.9 Ma event” glacial period. This increment of seasonality may have had an important effect on the Mediterranean habitats leading to recurring changes in the quality of plant resources available to large herbivores, which in response periodically adopted more mixed feeding behaviours widening their dietary breadth to consume also sub-optimal food items during adverse seasons.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 April 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 210〈/p〉 〈p〉Author(s): Michael Klinge, Daniela Sauer〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The effective humidity, resulting from the balance between evapotranspiration and precipitation, largely controls the environmental conditions under the highly continental, semi-humid to arid climate of Mongolia. Minor variations of temperature and precipitation have resulted in considerable environmental changes over the Holocene, affecting vegetation composition and density, soil formation, geomorphological activity, desertification processes, lake level and glacier distribution. Thus, various paleoclimatic archives have been investigated in several studies over the last decades. Here, we present an overview of the existing reconstructions of climatic changes over the Late Glacial and Holocene. The aim of this work is to obtain a spatially differentiated synthesis of the currently available paleoenvironmental information, and to point to existing contradictions and knowledge gaps.〈/p〉 〈p〉Our results suggest that during the Late Glacial, dry and cold conditions dominated, whereas the early Holocene was warm, and characterized by increasing humidity. 6000 years ago, the temperature began to decrease. Enhanced aridity occurred in the rain shadow east of the Altai and Khangai Mountains, pointing to increasing influence of the westerlies. In the Valley of Great Lakes, east of the Altai Mountains, the Late Glacial was characterized by high lake levels that steadily decreased over the Holocene. In the Valley of Gobi Lakes, south of the Khangai Mountains, high lake levels persisted from the early Holocene until the beginning of the mid-Holocene. In contrast, the lake level of Telmen Nuur, north of the Khangai Mountains, remained low until the end of the mid-Holocene. Periods of enhanced eolian transport and deposition occurred from the Late Glacial until the early Holocene, and again during the late Holocene. In between, during the mid-Holocene, no soil erosion by eolian and fluvial processes took place over large areas.〈/p〉 〈p〉The present state of research shows that the limited number of investigated archives and the unbalanced spatial distribution of the studied sites hamper an integrative reconstruction with appropriate spatial and temporal resolution. Paleoclimate interpretations by different authors, which were derived from the same archives or from neighboring archives in the same region diverge in paleotemperature and -humidity. Thus, paleoclimate at a regional scale of up to 100 km, as well as the timing of climate changes at a temporal scale of several centuries is still ambiguous in Mongolia. Further challenges include the multiple possible causes of lake level changes and the difficulty to distinguish (i) between climatic and anthropogenic impacts on vegetation and landscape, and (ii) between local, regional and global signals in the proxy data. In addition, there are ambiguities with respect to the ages of various materials that are obtained by radiocarbon and luminescence dating.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 April 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 210〈/p〉 〈p〉Author(s): Graeme T. Swindles, Zoe Outram, Catherine M. Batt, W. Derek Hamilton, Mike J. Church, Julie M. Bond, Elizabeth J. Watson, Gordon T. Cook, Thomas G. Sim, Anthony J. Newton, Andrew J. Dugmore〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Understanding the chronology of Norse settlement is crucial for deciphering the archaeology of many sites across the North Atlantic region and developing a timeline of human-environment interactions. There is ambiguity in the chronology of settlements in areas such as the Northern Isles of Scotland, arising from the lack of published sites that have been scientifically dated, the presence of plateaus in the radiocarbon calibration curve, and the use of inappropriate samples for dating. This novel study uses four absolute dating techniques (AMS radiocarbon, tephrochronology, spheroidal carbonaceous particles and archaeomagnetism) to date a Norse house (the “Upper House”), Underhoull, Unst, Shetland Isles and to interpret the chronology of settlement and peat which envelops the site. Dates were produced from hearths, activity surfaces within the structure, and peat accumulations adjacent to and above the structure. Stratigraphic evidence was used to assess sequences of dates within a Bayesian framework, constraining the chronology for the site as well as providing modelled estimates for key events in its life, namely the use, modification and abandonment of the settlement. The majority of the absolute dating methods produced consistent and coherent datasets. The overall results show that occupation at the site was not a short, single phase, as suggested initially from the excavated remains, but instead a settlement that continued throughout the Norse period. The occupants of the site built the longhouse in a location adjacent to an active peatland, and continued to live there despite the encroachment of peat onto its margins. We estimate that the Underhoull longhouse was constructed in the period 〈em〉cal. AD 805–1050〈/em〉 (95% probability), and most probably in 〈em〉cal. AD 880–1000〈/em〉 (68% probability). Activity within the house ceased in the period 〈em〉cal. AD 1230–1495〈/em〉 (95% probability), and most probably in 〈em〉cal. AD 1260–1380〈/em〉 (68% probability). The Upper House at Underhoull provides important context to the expansion and abandonment of Norse settlement across the wider North Atlantic region.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0277379118305444-fx1.jpg" width="306" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 April 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 210〈/p〉 〈p〉Author(s): Biancamaria Narcisi, Jean Robert Petit, Barbara Delmonte, Valentina Batanova, Joël Savarino〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Strong volcanic signals simultaneously recorded in polar ice sheets are commonly assigned to major low-latitude eruptions that dispersed large quantities of aerosols in the global atmosphere with the potential of inducing climate perturbations. Parent eruptions responsible for specific events are typically deduced from matching to a known volcanic eruption having coincidental date. However, more robust source linkage can be achieved only through geochemical characterisation of the airborne volcanic glass products (tephra) sometimes preserved in the polar strata. We analysed fine-grained tephra particles extracted from layers of the AD 1259 major bipolar volcanic signal in four East Antarctic ice cores drilled in different widely-spaced locations on the Antarctic Plateau. The very large database of glass-shard geochemistry combined with grain size analyses consistently indicate that the material was sourced from multiple distinct eruptions. These are the AD 1257 mega-eruption of Samalas volcano in Indonesia, recently proposed to be the single event responsible for the polar signal, as well as a newly-identified Antarctic eruption, which occurred in northern Victoria Land in AD 1259. Finally, a further eruption that took place somewhere outside of Antarctica has also contributed to tephra deposition. Our high-resolution, multiple-site approach was critical for revealing spatial heterogeneity of tephra at the continental scale. Evidence from ice-core tephra indicates recurrent explosive activity at the Antarctic volcanoes and could have implications for improved reconstruction of post-volcanic effects on climate from proxy polar records.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 April 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 210〈/p〉 〈p〉Author(s): F.N. Pupim, A.O. Sawakuchi, R.P. Almeida, C.C. Ribas, A.K. Kern, G.A. Hartmann, C.M. Chiessi, L.N. Tamura, T.D. Mineli, J.F. Savian, C.H. Grohmann, D.J. Bertassoli, A.G. Stern, F.W. Cruz, J. Cracraft〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the Amazonian lowlands, the shift from a large wetland dominated by flooded forests (Várzea) to the modern incised valleys bounded by extensive areas of non-flooded forests (Terra Firme) is considered a key driver of the Amazonian mega-biodiversity. Dating the sedimentary beds covered by Terra Firme forest is crucial to constrain the timing of such landscape change. Here we determined the formation ages of widespread regions of Terra Firme substrates in central Amazonian lowlands combining optically stimulated luminescence (OSL) dating, magnetostratigraphy and palinostratigraphy. Our data suggest a very dynamic fluvial system leading to a recent expansion of Terra Firme forests and retraction of Várzea forests during the late Pleistocene. The shift from an extensively flooded to non-flooded surface resulted from river incision around 45-35 ka, which potentially influenced the distribution of taxa by expanding available habitat, creating new barriers to dispersal, or changing the permeability of previous barriers. Transitions between flooded and non-flooded landscapes may have driven diversification and caused changes to species distributions, contributing to the high species diversity and biogeographic patterns currently found in the region. The late Quaternary evolution of Terra Firme substrates reveals that physical landscape changes play a major role in shaping biotic habitats even in the 10〈sup〉4〈/sup〉–10〈sup〉5〈/sup〉 years time-scales.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 218〈/p〉 〈p〉Author(s): Mónica Fernández-García, Aurélien Royer, Juan Manuel López-García, Maria Bennàsar, Jean Goedert, François Fourel, Marie-Anne Julien, Sandra Bañuls-Cardona, Antonio Rodríguez-Hidalgo, Josep Vallverdú, Christophe Lécuyer〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Small mammals, especially rodents, constitute valuable proxies for continental Quaternary environments at a regional and local scale. Recent studies have demonstrated the relation between the stable oxygen isotope composition of the biogenic phosphate from rodent teeth (δ〈sup〉18〈/sup〉O〈sub〉p〈/sub〉), and the oxygen isotope composition of meteoric waters (δ〈sup〉18〈/sup〉O〈sub〉mw〈/sub〉), which is related to air temperatures at mid and high latitudes. This work explores the δ〈sup〉18〈/sup〉O〈sub〉p〈/sub〉 of rodent tooth enamel (from Murinae and Arvicolinae subfamilies) to investigate the palaeoenvironmental conditions in northeastern Iberia during Marine Isotope Stage 3 (MIS 3; ca. 60-30 ka). Fourteen new δ〈sup〉18〈/sup〉O〈sub〉p〈/sub〉 analyses from modern samples in conjunction with forty-six δ〈sup〉18〈/sup〉O〈sub〉p〈/sub〉 analyses previously published are used to decipher the isotope record of present-day rodent teeth in this region. Two main factors should be considered in Iberian palaeoenvironmental reconstructions: the singular nature of Iberian δ〈sup〉18〈/sup〉O〈sub〉mw〈/sub〉 records and the potential seasonality bias of small-mammal accumulation. Methodological proposals are made with a view to ensuring the correct interpretation of the δ〈sup〉18〈/sup〉O〈sub〉p〈/sub〉 of small mammals in reconstructing past air temperatures. This methodology is applied to the MIS 3 sequence of the Cova dels Xaragalls site (Vimbodí-Poblet, Tarragona, Spain), where fifty-one δ〈sup〉18〈/sup〉O analyses were performed on wood mouse (〈em〉Apodemus sylvaticus〈/em〉) lower incisors. A spring-early summer accumulation of small mammals is suggested for the layers at Cova dels Xaragalls. In agreement with previous environmental studies of the site, variations in the δ〈sup〉18〈/sup〉O〈sub〉p〈/sub〉 values suggest slight fluctuations in the climatic conditions throughout the sequence, which are consistent with the stadial-interstadial alternations that characterized MIS 3. Complementary palaeoenvironmental methods determine cooler conditions than nowadays, but within a globally stable climatic period.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 212〈/p〉 〈p〉Author(s): C. Thomas, D. Ariztegui〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Dead Sea Deep Drilling Project allowed us to retrieve a continuous sedimentary record spanning the two last glacial cycles. This unique archive, in such an extreme environment, has permitted the development of new proxies and the refinement of already available paleoenvironmental studies. Although life is pushed to its extremes in the Dead Sea environment, several studies have highlighted the impact of microbial activity on this harsh milieu. The identity and means of adaptation of these organisms are however partly ignored. We also know relatively little on the way this extreme ecosystem has evolved with time, and how it will react to growing pressure. In this study, we have used the fluid inclusions trapped in halite, the main evaporitic phase during arid periods in the Dead Sea, to investigate the way the Dead Sea ecosystem has evolved. By extracting ancient DNA from Holocene halite fluid inclusions, we have obtained fossil bacterial and archaeal 16S rRNA gene sequences that suggest that the main microbial actors of the present Dead Sea have been present in the lake for a relatively long period, emphasizing the stability of this extreme environment. This is the case of extreme halophilic archaea of the 〈em〉Salinarchaeum〈/em〉 genera. Additionally, we show that current phylotypes of the deep biosphere, such as 〈em〉Acetothermia〈/em〉 bacteria are present within the obtained fluid inclusions sequences, which would support seeding of the deep biosphere from the water column. Finally, through the retrieval of sequences assigned to 〈em〉Halodesulfurarchaeum〈/em〉 and 〈em〉Desulfovermiculus〈/em〉 genera, we shed light on putative new actors of the sulfur cycle involving respectively archaea and bacteria, which could play an unexpected role in the reduction of sulfur species. Together, these data provide new research avenues for both geologists and biologists working in this extreme environment, and help to increase understanding of the evolution of the Dead Sea ecosystem with time.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 2 April 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Dennis Dahms, Markus Egli, Derek Fabel, Jon Harbor, Dagmar Brandová, Raquel de Castro Portes, Marcus Christl〈/p〉

Description: 〈p〉Publication date: 15 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 218〈/p〉 〈p〉Author(s): Rebecca E. Smith, Victoria C. Smith, Karen Fontijn, A. Catalina Gebhardt, Stefan Wastegård, Bernd Zolitschka, Christian Ohlendorf, Charles Stern, Christoph Mayr〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper presents a detailed record of volcanism extending back to ∼80 kyr BP for southern South America using the sediments of Laguna Potrok Aike (ICDP expedition 5022; Potrok Aike Maar Lake Sediment Archive Drilling Project - PASADO). Our analysis of tephra includes the morphology of glass, the mineral componentry, the abundance of glass-shards, lithics and minerals, and the composition of glass-shards in relation to the stratigraphy. Firstly, a reference database of glass compositions of known eruptions in the region was created to enable robust tephra correlations. This includes data published elsewhere, in addition to new glass-shard analyses of proximal tephra deposits from Hudson (eruption units H〈sub〉1〈/sub〉 and H〈sub〉2〈/sub〉), Aguilera (A〈sub〉1〈/sub〉), Reclus (R〈sub〉1〈/sub〉, R〈sub〉2-3〈/sub〉), Mt Burney (MB〈sub〉1〈/sub〉, MB〈sub〉2〈/sub〉, MB〈sub〉x〈/sub〉, MB〈sub〉1910〈/sub〉) and historical Lautaro/Viedma deposits. The analysis of the ninety-four tephra layers observed in the Laguna Potrok Aike sedimentary sequence reveals that twenty-five tephra deposits in the record are the result of primary fallout and are sourced from at least three different volcanoes in the Austral Andean Volcanic Zone (Mt Burney, Reclus, Lautaro/Viedma) and one in the southernmost Southern Volcanic Zone (Hudson). One new correlation to the widespread H〈sub〉1〈/sub〉 eruption from Hudson volcano at 8.7 (8.6–9.0) cal ka BP during the Quaternary is identified. The identification of sixty-five discrete deposits that were predominantly volcanic ashes (glass and minerals) with subtle characteristics of reworking (in addition to three likely reworked tephra, and one unknown layer) indicates that care must be taken in the analysis of both visible and invisible tephra layers to decipher their emplacement mechanisms.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 218〈/p〉 〈p〉Author(s): Sophie F. Warken, Denis Scholz, Christoph Spötl, Klaus P. Jochum, Jesús M. Pajón, André Bahr, Augusto Mangini〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We present a new speleothem trace element and stable isotope record, which extends previous paleoclimate evidence from Cuban speleothems to the last 96 ka. Multiple proxies were used to reconstruct Caribbean hydroclimate and vegetation variability on orbital to millennial timescales. In particular, our proxies indicate a shift to more abundant C4 (compared to C3) vegetation and/or reduced soil activity during the Last Glacial Maximum. Our results confirm the close link of Caribbean precipitation to North Atlantic climate variability, insolation and the strength of the AMOC. The associated variations in Caribbean SSTs and the shift of the ITCZ led to substantial changes of the hydrological cycle. During Heinrich stadials and the Younger Dryas, climatic conditions in Cuba were comparably cool and/or dry. In contrast, warm Dansgaard/Oeschger cycles were accompanied by wetter conditions. This is in agreement with previous evidence for the Holocene, when North Atlantic cold (warm) events coincided with drier (wetter) conditions in Cuba. However, our record suggests that this connection was less dominant during MIS 4 to 2, displayed by a weaker response of Cuban precipitation proxies to North Atlantic climatic shifts than during MIS 5 in particular. We hypothesize that this weaker connection was mediated by the southerly shifted ITCZ inducing a weakening of the northern branch of the Caribbean Low Level Jet which usually transports moisture into the northern Caribbean. This is strikingly evident during the deglacial, when driest and/or coolest conditions prevailed in western Cuba from HS 1 into the Younger Dryas, including the Bølling/Allerød interstadial.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 218〈/p〉 〈p〉Author(s): Geert W. van der Plas, Gijs De Cort, Nik Petek-Sargeant, Tabitha Wuytack, Daniele Colombaroli, Paul J. Lane, Dirk Verschuren〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Socio-ecological stresses currently affecting the semi-arid regions of equatorial East Africa are driving environmental changes that need to be placed in a proper context of long-term human-climate-landscape interaction. Here we present a detailed reconstruction of past human influences on the landscape of the central Kenya Rift Valley, against the backdrop of natural climate-driven ecosystem dynamics over the past 1300 years. Proxy records of vegetation dynamics (pollen), animal husbandry (fungal spores), biomass burning (charcoal) and soil mobilization (clastic mineral influx) extracted from the continuous depositional archive of Lake Bogoria reveal six distinct phases of human activity. From 〈em〉ca〈/em〉 700 to 1430 CE, strong primary response of savanna woodland ecotonal vegetation to climatic moisture-balance variation suggests that anthropogenic influence on regional ecosystem dynamics was limited. The first unambiguous ecological signature of human activities involves a mid-15th century reduction of woodland/forest trees followed by the appearance of cereal pollen, both evidence for mixed farming. From the mid-17th century, animal husbandry became a significant ecological factor and reached near-modern levels by the mid-19th century, after severe early-19th century drought had substantially changed human-landscape interaction. A short-lived peak in biomass burning and evidence for soil mobilization in low-lying areas of the Bogoria catchment likely reflects the known 19th-century establishment of irrigation agriculture, while renewed expansion of forest and woodland trees reflect the return of a wetter climate and abandonment of other farmland. Since the mid-20th century, the principal signature of human activity within the Lake Bogoria catchment is the unprecedented increase in clastic sediment flux, reflecting widespread soil erosion associated with rapidly intensifying land use.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0277379118308643-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 218〈/p〉 〈p〉Author(s): Christoph Mayr, Philipp Stojakowits, Bernhard Lempe, Maarten Blaauw, Volker Diersche, Madleen Grohganz, Matthias López Correa, Christian Ohlendorf, Paula Reimer, Bernd Zolitschka〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ravine slopes at the recently discovered Nesseltalgraben site in southeastern Germany provide a unique last glacial sediment record for the Northern Calcareous Alps. The 21 m-long profile is dominated by fine-grained lacustrine-palustrine sediments overlain by several metres of glacifluvial gravels and lodgement tills of the Last Glacial Maximum and underlain by a diamicton. The age model includes 29 radiocarbon analyses and one paleomagnetic anomaly (Laschamp event) together providing a modelled age range from 〈em〉c〈/em〉. 59 to 29.6 ka cal BP, i.e. Marine Isotope Stage (MIS) 3. Apart from a description of the lithofacies, X-ray-fluorescence (XRF) scanning and elemental analyses provide high-resolution records of the geochemical composition. Multivariate analyses of XRF data separate Ca from other major elements. Carbonate contents, represented by Ca and total inorganic carbon, reach maxima in repeatedly occurring calcareous silty to sandy layers and are related to glacigenic origin. These indicate repeated inner-alpine local glaciations during stadials of MIS 3. Scanning electron microscopy and XRF data confirm the detrital origin of these layers. In contrast, organic matter and elements more resistant to chemical weathering (Si, Ti, Zr) accumulated during interstadials and concurrently elevated Rb/Sr ratios indicate intensified weathering. The high-frequency proxy variations determined for Nesseltalgraben reflect interstadial-stadial climate variability comparable with oxygen-isotope records from Greenland ice cores and Alpine speleothems. Thus, Nesseltalgraben is among the very few independently dated sediment records from continental Europe covering the entire MIS 3 and reflecting the full Dansgaard-Oeschger climate variability.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 218〈/p〉 〈p〉Author(s): Sietse O. Los, F. Alayne Street-Perrott, Neil J. Loader, Cynthia A. Froyd, Aida Cuní-Sanchez, Robert A. Marchant〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉During the Last Glacial Maximum (LGM) lowland forests contracted throughout the tropics but, by contrast, many montane forest taxa moved to lower elevations. These taxa are often found in cloud forests, which are globally important ecosystems that depend on the capture of atmospheric water from fog drifting through the canopy, here referred to as occult precipitation. Understanding the response of tropical montane taxa to climate variations is limited by a lack of modern data on fog capture; whereas palaeoecological data only provide indirect evidence for its importance. Hence, the response of vegetation to fog capture is not considered in palaeo-estimates of precipitation. We develop a method that uses satellite Normalized Difference Vegetation Index (NDVI) data to estimate the annual amount of occult precipitation and investigate the sensitivity of a cloud forest to past and future changes in both rainfall and occult precipitation. We apply this method using satellite and meteorological data from 1982 to 2015 collected at Mt Marsabit, which is located in northern Kenya (2.34〈sup〉∘〈/sup〉 N, 37.97〈sup〉∘〈/sup〉 E, summit 1707 m a.s.l.). Mt Marsabit has a sub-humid tropical montane cloud forest at its summit that is excessively green for the amount of rain it receives. We estimate the annual amount of occult precipitation for current conditions at about 900 mm y〈sup〉−1〈/sup〉 which is more than the average annual rainfall of 700 mm y〈sup〉−1〈/sup〉. This is consistent with the observation that, for the wider Marsabit area, interannual variations in NDVI are more closely linked to changes in cloud-base height (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈msup〉〈mrow〉〈mi〉r〈/mi〉〈/mrow〉〈mrow〉〈mn〉2〈/mn〉〈/mrow〉〈/msup〉〈mo linebreak="goodbreak" linebreakstyle="after"〉=〈/mo〉〈mn〉0.87〈/mn〉〈/mrow〉〈/math〉) than to changes in rainfall (〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.svg"〉〈mrow〉〈msup〉〈mrow〉〈mi〉r〈/mi〉〈/mrow〉〈mrow〉〈mn〉2〈/mn〉〈/mrow〉〈/msup〉〈mo linebreak="goodbreak" linebreakstyle="after"〉=〈/mo〉〈mn〉0.67〈/mn〉〈/mrow〉〈/math〉). We investigate the sensitivity of forest extent to past and future changes; for the LGM we estimate that cloud-base height decreased by 500 m in response to a 4 〈sup〉∘〈/sup〉C cooling and that this caused a 20%–100% increase in forest area despite a 30% decrease in rainfall, a 22% decrease in atmospheric humidity and a substantial reduction of atmospheric CO〈sub〉2〈/sub〉 levels (values representative for mountains in Kenya during the LGM). An expected increase of 250 m in the cloud-base height associated with a future 2 〈sup〉∘〈/sup〉C global warming is likely to reduce forest extent by 50%–100%. Our results indicate that the satellite vegetation record is useful to estimate modern hydrological inputs into drier cloud forests (up to 2000 mm y〈sup〉−1〈/sup〉) and that this information can be used to estimate the contribution of occult precipitation to altitudinal displacements of tropical montane cloud-forest species during the Quaternary.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 July 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 216〈/p〉 〈p〉Author(s): J.S. Honke, J.S. Pigati, J. Wilson, J. Bright, H.L. Goldstein, G.L. Skipp, M.C. Reheis, J.C. Havens〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Sediment cores taken near extant springs along the western margin of Soda Lake playa, as well as from the playa center, reveal dramatic hydrologic changes that occurred in the central Mojave Desert during the late Quaternary. Results of stratigraphic, chronologic, physical, chemical, and microfossil analyses of seven cores, ranging in length from 5 to 23 m, help refine the timing and character of the final stages of pluvial Lake Mojave during the late Pleistocene and define distinct periods of wetland development in the early and late Holocene. Evidence shows that an incipient lake occupied the central Soda Lake basin by at least 25.0 ka (ka = thousands of calibrated 〈sup〉14〈/sup〉C years before present), and a fully developed Lake Mojave was present between 20.5 and 12.8 ka, before receding and ultimately yielding to playa conditions by 11.0 ka. Organic-rich “black mats” appear in several cores along the playa margin between 10.7 and 9.0 ka, suggesting that spring-fed wetlands persisted in this area long after the lake had regressed. The basin remained relatively dry throughout most of the Holocene until wetland ecosystems expanded along the margins between 0.73 and 0.18 ka, coincident with part of the Medieval Climate Anomaly and Little Ice Age. Overall, our results demonstrate that buried sediments surrounding extant and extinct springs can be used to reconstruct past hydrologic conditions in desert environments on a variety of spatial and temporal scales, and provide important baseline information for effective management of limited desert resources.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 211〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 15 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 212〈/p〉 〈p〉Author(s): Hongye Liu, Yansheng Gu, Xianyu Huang, Zicheng Yu, Shucheng Xie, Shenggao Cheng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Quantitative reconstructions of the depth to water table (DWT) of ombrotrophic (rain-fed) peatlands are important for understanding the palaeohydrological responses of peatlands to past climate changes. This understanding can provide insights into projecting peatlands future variability and evolution. However, the postglacial DWT reconstruction of peatlands in China is challenging due to complications of the atmospheric circulation system, the scarcity of hydrological proxies, and the site-specific nature of hydrological signals. Here we present a postglacial quantitative DWT reconstruction based on the analysis of fossil phytoliths from the Dajiuhu Peatland, central China. The reconstructions were based on a phytolith-DWT calibration model using a weighted averaging partial least-squares regression analysis of peatland topsoil calibration datasets. Three shallow DWT (wet) periods at 13,000–11,500 cal yr BP, 9,600–7,500 cal yr BP, and 3,000 cal yr BP-present, and two extended deep DWT (dry) periods at 11,500–9600 cal yr BP and at 7,500–3,000 cal yr BP are found based on the cluster analysis of phytolith assemblages and reconstructed DWT changes. These five documented hydrological periods are consistent with regional precipitation reconstructions from independent records in the middle Yangtze Valley (MYV). We interpret these changes as mostly reflecting changes in ENSO at various timescales. An amplified ENSO forced a southward Western Pacific Subtropical High and caused the persistence of the Meiyu Front in the mid-lower Yangtze Valley, consistent with the intense rainfall periods in our study region. Our results indicate that phytolith records are a reliable and sensitive proxy for the calibration of water table models and the quantitatively palaeo-DWT reconstruction of peatlands and reveal a remarkable link between the local hydrological variations and the coupled atmospheric-oceanic circulation, which is significant for the prediction of future hydrological changes in the Asian monsoon region under the background of global warming.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 212〈/p〉 〈p〉Author(s): I.N. McCave, J.T. Andrews〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉There are climatically important ocean flow systems in high latitudes, for example the East and West Greenland and Labrador Currents and Nordic Sea overflows in the North, and Antarctic Circumpolar Current in the South, for which it would be useful to know history of flow strength. Most of the sediment records under these flows contain evidence of supply from glacial sources, which has led to the supposition that fine sediment records, which in other settings provide evidence of vigour of flow from the sortable silt proxy, are fatally contaminated by unsorted glacial silt. It is suggested here that if the fine fraction (〈63 μm) has been transported and sorted, then it does not matter that it may have been released from icebergs, sea ice or meltwater plumes. Here we show that correlation between sortable silt mean and percentage provides a good indicator of whether a fine sediment record has been sufficiently well current-sorted to provide a reliable flow history. The running downcore correlation (r〈sub〉run〈/sub〉) (5 to 9-point depending on sampling interval) is found to be optimal, and a value of r〈sub〉run〈/sub〉 〈 0.5 is proposed as an indicator of sufficiently poor sorting to invalidate a section of mean size record. More than 40 grainsize records determined by laser particle sizers from over 30 core sites have been processed and examined for evidence of sorting. As expected, there is a tendency for poor sorting and unreliable records at points where the flow speed has decreased to very low values. There is no consistent relationship between the sorting of the fine fraction and the content of coarse ice-rafted debris (as long as the IRD fraction is not 〉 50%) because the two are not related. End member (EM) decomposition of several records yields variable results in terms of the relationship between EM ratios and grainsize parameters. Although such an approach can generate fine sediment parameters it does not provide a basis for deciding whether or not a record is acceptably current sorted and thus contains a valid flow speed proxy. Our proposed discrimination between current-sorted and unsorted fine fractions is applicable to all fine grained deposits, not only high-latitude deposits with coarse IRD.〈/p〉 〈p〉Examples from East Greenland, Faroe Bank Channel, Gardar Drift show mainly well sorted signatures. Amounts of coarse IRD range up to 60% with only those 〉50% having a consistent impact on sortable silt mean size. With the exception of a Southern Ocean site on the Antarctic continental rise where half the record is poorly sorted, the silt mean data are sufficiently well sorted to provide credible flow speed histories. This bodes well for the extraction of such histories from climatically important high-latitude flows such as the East Greenland Current.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 212〈/p〉 〈p〉Author(s): F. Naughton, S. Costas, S.D. Gomes, S. Desprat, T. Rodrigues, M.F. Sanchez Goñi, H. Renssen, R. Trigo, C. Bronk-Ramsey, D. Oliveira, E. Salgueiro, A.H.L. Voelker, F. Abrantes〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Paleoclimate reconstructions suggest that the complex variability within the Greenland stadial 1 (GS-1) over western Europe was governed by coupled ocean and atmospheric changes. However, few works from the North Atlantic mid-latitudes document both the GS-1 onset and its termination, which are often considered as single abrupt transition events. Here, we present a direct comparison between marine (alkenone-based sea surface temperatures) and terrestrial (pollen) data, at very high resolution (28 years mean), from the southwestern Iberian shelf record D13882. Our results reveal a rather complex climatic period with internally changing conditions. The GS-1 onset (GS-1a: 12890-12720 yr BP) is marked by a progressive cooling and drying; GS-1b (12720-12390 yr BP) is the coldest and driest phase; GS-1c (12390-12030 yr BP) is marked by a progressive warming and increase in moisture conditions; GS-1 termination (GS-1d: 12030-11770 yr BP) is marked by rapid switches between cool wet, cold dry and cool wet conditions. Although hydroclimate response was very unsteady throughout the GS-1 and in particular during its termination phase, the persistence of an open temperate and Mediterranean forest in southwestern Iberia during the entire episode suggests that at least some moisture was delivered via the Westerlies. We propose coupled ocean and atmospheric mechanisms to reproduce these 〈em〉scenaria〈/em〉. Changes in the strength of the Atlantic Meridional Overturning Circulation (AMOC) as well as variations in the North Atlantic sea-ice growth have favoured the displacement of the polar jet stream's latitudinal position and contributed to a complex spatial pattern and strength of the Westerlies across western Europe.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 212〈/p〉 〈p〉Author(s): Jasper G. Franke, Reik V. Donner〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Comparing paleoclimate time series is complicated by a variety of typical features, including irregular sampling, age model uncertainty (e.g., errors due to interpolation between radiocarbon sampling points) and time uncertainty (uncertainty in calibration), which—taken together—result in unequal and uncertain observation times of the individual time series to be correlated. Several methods have been proposed to approximate the joint probability distribution needed to estimate correlations, most of which rely either on interpolation or temporal downsampling.〈/p〉 〈p〉Here, we compare the performance of some popular approximation methods using synthetic data resembling common properties of real world marine sediment records. Correlations are determined by estimating the parameters of a bivariate Gaussian model from the data using Markov Chain Monte Carlo sampling. We complement our pseudoproxy experiments by applying the same methodology to a pair of marine benthic 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mrow〉〈msup〉〈mrow〉〈mi〉δ〈/mi〉〈/mrow〉〈mrow〉〈mn〉18〈/mn〉〈/mrow〉〈/msup〉〈/mrow〉〈/math〉 O records from the Atlantic Ocean.〈/p〉 〈p〉We find that methods based upon interpolation yield better results in terms of precision and accuracy than those which reduce the number of observations. In all cases, the specific characteristics of the studied time series are, however, more important than the choice of a particular interpolation method. Relevant features include the number of observations, the persistence of each record, and the imposed coupling strength between the paired series. In most of our pseudoproxy experiments, uncertainty in observation times introduces less additional uncertainty than unequal sampling and errors in observation times do. Thus, it can be reasonable to rely on published time scales as long as calibration uncertainties are not known.〈/p〉 〈/div〉 〈/div〉