ALBERT

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 201〈/p〉 〈p〉Author(s): Matteo Vacchi, Matthieu Ghilardi, Rita T. Melis, Giorgio Spada, Matthieu Giaime, Nick Marriner, Thomas Lorscheid, Christophe Morhange, Francesc Burjachs, Alessio Rovere〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A recent suite of Relative Sea-Level (RSL) data for the past 12 ka BP has provided new insights into the sea-level histories of the western Mediterranean region. Our analysis of the chronostratigraphic context of sea-level indicators from Spain (Catalonia, the Balearic Islands and the Gulf of Valencia), France (Corsica Island) and Italy (Sardinia Island) has yielded 162 new sea-level index and limiting points. These data have considerably enhanced previous RSL compilations, in addition to improving the quality of spatio-temporal sea-level reconstructions and our capacity to estimate isostatic-related vertical motions in the western Mediterranean basin. The glacial and hydro-isostatic adjustment (GIA) pattern elucidated by the new database shows discrepancy with respect to those predicted by the available GIA models. In particular, the new results underscore a non-coherent isostatic response of the central portion of the western Mediterranean, with the Balearic Islands manifesting significant departures from the sea-level histories of Corsica, Sardinia and, more generally, along most of the western Mediterranean coast. Our results are a crucial contribution to defining both the pattern and the magnitude of the isostatic signal along the western Mediterranean coast. In fact, vertical isostatic motions represent a key to better assess any possible post-industrial acceleration in sea-level rise and to define future scenarios of coastal inundation in the context of global change.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 204〈/p〉 〈p〉Author(s): Byron A. Steinman, Daniel B. Nelson, Mark B. Abbott, Nathan D. Stansell, Matthew S. Finkenbinder, Bruce P. Finney〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Multi-proxy sediment records from Castor Lake and Scanlon Lake, north-central Washington, provide a late Quaternary perspective on lake/catchment hydrologic and ecosystem responses to climate change and the Mazama volcanic ashfall event. Analyses of authigenic carbonate mineral oxygen and carbon isotope values, organic carbon and nitrogen content, and sedimentological facies were conducted on sediment from Castor Lake in order to reconstruct lake/catchment hydrologic balance, the source and abundance of organic matter, and variations in lake level. Sedimentary facies characterization was conducted on the Scanlon Lake sediment in order to provide supporting evidence for the lake-level shifts inferred from the Castor Lake data. Marked changes in Castor Lake proxy values occur from 12,860 to 11,440 calendar years before present (yr BP), suggesting lake/catchment responses to the Younger Dryas cold reversal including higher lake levels, substantial variability in productivity, and increased catchment erosion. High δ〈sup〉18〈/sup〉O values at 9630 yr BP indicate that lake levels were lower than at present and that the early Holocene was dry. Sedimentological analyses and δ〈sup〉18〈/sup〉O data demonstrate that subsequent to the Mazama climactic eruption (∼7600 yr BP), a transition to the lowest lake levels of the Holocene occurred over several centuries, with maximum δ〈sup〉18〈/sup〉O values at 7290 (90% uncertainty range: 7020–7500) yr BP and low lake levels persisting until 6190 (5960–6410) yr BP. Lithological changes in the Scanlon Lake record support these inferences. The lowest δ〈sup〉18〈/sup〉O values of the Holocene occur in sediment from ∼5000 yr BP, indicating high lake levels at this time, after which a secular trend toward higher δ〈sup〉18〈/sup〉O values and lower lake levels occurred. The prolonged lowstand in the centuries following the Mazama eruption suggests that catchment hydrologic characteristics were strongly impacted by the ashfall through effects on soil water retention capacity, that similar responses may have occurred in comparable settings within the Mazama ashfall zone, and that such volcanic events have the potential confound the climate signal in lake sediment records. Were a similar event to happen in the future, catchment hydrology, stream/river discharge, and lake/catchment ecosystem dynamics could be affected for centuries.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 205〈/p〉 〈p〉Author(s): Zhaojie Yu, Christophe Colin, Shiming Wan, Rajeev Saraswat, Lina Song, Zhaokai Xu, Peter Clift, Huayu Lu, Mitchell Lyle, Denise Kulhanek, Annette Hahn, Manish Tiwari, Ravi Mishra, Serge Miska, Anil Kumar〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Long marine sequences deposited in the Arabian Sea are suitable to study the orbital sensitivity of sediment dynamics from a source-to-sink perspective. The clay mineralogy and Sr〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Nd isotopic compositions have been analyzed for the detrital fraction of sediments from IODP Site U1457 located in the Laxmi basin, eastern Arabian Sea to constrain the sediment sources and reconstruct a high-resolution record of sediment export to the Indus deep-sea fan over the past 600 kyr. The 〈sup〉87〈/sup〉Sr/〈sup〉86〈/sup〉Sr ratio (varying from 0.7154 to 0.7255) and εNd (varying from −12.9 to −9.5) imply a mixing of sediments derived from not only the Indus River but also the rivers draining the Deccan Traps. The variations in the smectite/(illite + chlorite) ratio combined with Sr〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Nd isotopes permit the reconstruction of past changes in the relative proportions of sediments derived from the Indus River (mainly illite, chlorite and kaolinite) and the Deccan Traps (smectite). The wavelet and cross-spectral analyses further reveal that sediment transport to the eastern Arabian Sea since 600 kyr is mainly dominated by sea-level variations in the eccentricity (100-kyr) band, while the Indian summer monsoon might contribute moderately to the precession (23-kyr) band. The εNd and turbidite frequency indicate that more turbidite events are associated with Indus River-sourced sediments at IODP Site U1457 during sea-level lowstands, which might reflect a reconnection of deep-sea channels to the Indus River mouth and/or reworking of previously deposited Indus River sediments located northward.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 205〈/p〉 〈p〉Author(s): Richard S. Vachula, Yongsong Huang, William M. Longo, Sylvia G. Dee, William C. Daniels, James M. Russell〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Our understanding of the timing and pathway of human arrival to the Americas remains an important and polarizing topic of debate in archaeology and anthropology. Traditional consensus, supported by archaeological and paleoenvironmental data, favors a ‘swift peopling’ of the Americas from Asia via the Bering Land Bridge during the last Glacial termination. More recent genetic data and archaeological finds have challenged this view, proposing the ‘Beringian standstill hypothesis’ (BSH), wherein a population of proto-Americans migrated from Asia during, or even prior to the Last Glacial Maximum (LGM) and lived in Beringia for thousands of years before their eventual spread across the American continents. Using a sediment archive from Lake E5 (68.641667° N, 149.457706° W), located on Alaska's North Slope, we present new data supporting the BSH and shedding new light on the environmental impact of these early American populations. Fecal biomarkers support human presence in the environs of the lake, and our data demonstrate elevated biomass burning in this region during the last Glacial. Elevated burning defies the expectation that natural fires would be less frequent in the Arctic during the last Glacial, thereby suggesting human ignition as the likely culprit. Our data shed new light on the pathway and timing of human migration to the Americas and demonstrate the possibility of the sustainable coexistence of humans and the Ice Age megafauna in Beringia prior to their extinction.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 204〈/p〉 〈p〉Author(s): Mitch D'Arcy, Taylor F. Schildgen, Manfred R. Strecker, Hella Wittmann, Walter Duesing, Jürgen Mey, Stefanie Tofelde, Philipp Weissmann, Ricardo N. Alonso〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Advances in cosmogenic nuclide exposure dating have made moraines valuable terrestrial recorders of palaeoclimate. A growing number of moraine chronologies reported from the Central Andes show that tropical glaciers responded sensitively to past changes in precipitation and temperature over timescales ranging from 10〈sup〉3〈/sup〉 to 10〈sup〉5〈/sup〉 years. However, the causes of past glaciation in the Central Andes remain uncertain. Explanations have invoked insolation-modulated variability in the strength of the South American Summer Monsoon, teleconnections with the North Atlantic Ocean, and/or cooling in the Southern Hemisphere. The driver for these past climate changes is difficult to identify, partly due to a lack of dated moraine records, especially in climatically sensitive areas of the southern Central Andes. Moreover, new constraints are needed on precisely where and when glaciers advanced. We use cosmogenic 〈sup〉10〈/sup〉Be produced in situ to determine exposure ages for three generations of moraines at the Sierra de Aconquija, situated at 27°S on the eastern flank of the southern Central Andes. These moraines record glacier advances at approximately 22 ka and 40 ka, coincident with summer insolation maxima in the sub-tropics of the Southern Hemisphere, as well as at 12.5 ka and 13.5 ka during the Younger Dryas and the Antarctic Cold Reversal, respectively. We also identify minor glaciation during Bond Event 5, also known as the 8.2 ka event. These moraines register past climate changes with high fidelity, and currently constitute the southernmost dated record of glaciation on the eastern flank of the Central Andes. To contextualise these results, we compile 〈sup〉10〈/sup〉Be data reported from 144 moraines in the eastern Central Andes that represent past glacier advances. We re-calculate exposure ages from these data using an updated reference production rate, and we re-interpret the moraine ages by taking the oldest clustered boulder age (after the exclusion of outliers attributed to nuclide inheritance) as closest to the timing of glacier advance—an approach for which we provide empirical justification. This compilation reveals that Central Andean glaciers have responded to changes in temperature and precipitation. We identify cross-latitude advances in phase with insolation cycles, the last global glacial maximum, and episodes of strengthened monsoonal moisture transport including the Younger Dryas and Heinrich Stadials 1 and 2. Our results from the Sierra de Aconquija allow us to constrain the southerly limit of enhanced precipitation associated with Heinrich Stadials at ∼25°S. More broadly, our findings demonstrate at both local and regional scales that moraines record past climate variability with a fine spatial and temporal resolution.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 205〈/p〉 〈p〉Author(s): Christopher T. Hayes, Davin J. Wallace〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Despite evidence for an anti-correlation between African dust emissions and Atlantic hurricane activity in the instrumental period, there is debate as to whether there is any direct causal relationship between these two parameters. In this study, we provide a focused review of available African dust and storm activity records over 3 increasing timescales: the past 200 years, the past 3000 years and the past 12,000 years. In all three timescales, we find evidence for non-stationary, weak or unexpected relationships between African dust emissions and tropical cyclone activity. We suggest future storm record compilations that can better distinguish the relative frequency of storms generated in the eastern versus western development region of the tropical North Atlantic will provide a better test of the radiative impact of African dust over the past 3000 years and Holocene. Additionally, high resolution dust deposition records from the western Atlantic measured in the same cores used to derive storm records may provide much more detailed insight into how the variability in magnitude and spatial extent of the African dust plume has co-evolved with Atlantic storm tracks over recent millennia.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 204〈/p〉 〈p〉Author(s): Simon T. Belt〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Significant changes to Arctic and Antarctic sea ice in recent decades has prompted the development and application of novel approaches to the reconstruction of past sea ice conditions over much longer timeframes. One such approach is based on the variable distribution of certain source-specific highly branched isoprenoid (HBI) lipid biomarkers in well-dated marine sediment records. Thus, IP〈sub〉25〈/sub〉 and IPSO〈sub〉25〈/sub〉 have emerged as useful proxy measures of seasonal sea ice in the Arctic and Antarctic, respectively. An overview of the salient features of IP〈sub〉25〈/sub〉, IPSO〈sub〉25〈/sub〉 and related biomarkers is presented, together with aspects that are currently less well understood and potentially provide direction for future research.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 204〈/p〉 〈p〉Author(s): Yusuke Suganuma, Yuki Haneda, Koji Kameo, Yoshimi Kubota, Hiroki Hayashi, Takuya Itaki, Masaaki Okuda, Martin J. Head, Manami Sugaya, Hiroomi Nakazato, Atsuo Igarashi, Kizuku Shikoku, Misao Hongo, Masami Watanabe, Yasufumi Satoguchi, Yoshihiro Takeshita, Naohisa Nishida, Kentaro Izumi, Kenji Kawamura, Moto Kawamata〈/p〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 206〈/p〉 〈p〉Author(s): J. Shulmeister, G.D. Thackray, T.M. Rittenour, D. Fink, N.R. Patton〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper constitutes a review of the last (Otiran) glaciation in New Zealand, spanning marine isotope stages (MIS) 4-2. We highlight the nature of glaciation, which is characterised by exceptional sedimentation, relatively mild maritime climatic conditions and the widespread presence of water associated with proglacial settings. These conditions produce glacial systems characterised by extensive outwash fans and relatively small terminal moraines. Extensive recent geochronological work allows us to recognise at least eight glacial advances during the Otiran. These occurred at 65 ± 3.25ka, 47.5 ± 3 ka, 38.5 ± 2 ka, 31.5 ± 3 ka, 26.5 ± 2 ka, 20.5 ± 2 ka, 17 ± 2 ka and 13 ± 1 ka, which we term the Otira 1 to 8 advances, respectively. Though the analytical uncertainty ranges for some of these advances overlap, all are independently distinguished through moraine morphologic relationships and/or stratigraphic relationships in outcrop. Major advances appear to be associated with climate influences such as periods of Southern Hemisphere insolation minima (65ka, and 31.5 ka advances), the last glacial maximum cooling (LGM) (20.5 ka) and periods of Antarctic cooling (13ka). The timing of greatest glacial extent in the last glacial cycle is not simultaneous across New Zealand. The MIS 4 advance was the greatest in the southern South Island, while the MIS 3/2 advances (26.5 ka) were greatest in the central South Island. In the northern South Island and the North Island, MIS 4, MIS 3/2, and the last glacial maximum appear to be equivalent in extent. We attribute these spatio-temporal variations in the timing of maximum glaciation to precipitation changes related to a northward shift in the track of the westerlies.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 205〈/p〉 〈p〉Author(s): I. Hernández-Almeida, B. Ausín, M. Saavedra-Pellitero, K.-H. Baumann, H.M. Stoll〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ocean net primary productivity (Npp) is a key component of the marine carbon cycle. Multi-model Npp projections based on a few decades of satellite data show large uncertainties, in particular at low latitudes (30°N−30°S). Calibration of sedimentary proxies with satellite-based Npp estimates allows for the quantitative reconstruction of this variable at longer time-scales. Relative abundance of deep-photic zone coccolithophore species 〈em〉Florisphaera profunda〈/em〉 in the fossil record can potentially be used as a quantitative proxy for Npp. However, the robustness of this proxy calibration has been tested in very specific oceanographic settings using surface sediment samples. Here, we use a global dataset of surface sediment (n = 1258) and sediment trap (n = 26) samples with relative abundance data of 〈em〉F. profunda〈/em〉 (%) to test the robustness of this proxy as a quantitative indicator of Npp. We study the modern and paleo-ecology of this species and the main factors affecting its latitudinal distribution. Results show that 〈em〉F. profunda〈/em〉 % is a strong indicator of Npp at latitudes between 30°N and 30°S, while at higher latitudes temperature-related variables are more important. We develop a global calibration model between satellite Npp estimates and 〈em〉F. profunda〈/em〉 for the latitudinal range between 30°N and 30°S, and we apply it to several low-latitude sediment cores with available 〈em〉F. profunda〈/em〉 counts covering the Late Glacial Maximum (LGM; 24–19 ka) and the Mid-to-Late Holocene period (MLH; 〈6 ka). Reconstructed Npp during the LGM is 15% higher than during the MLHdue to the intensification of trade winds that enhanced oceanic upwelling at low latitudes.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 205〈/p〉 〈p〉Author(s): M.F. Raczka, N.A. Mosblech, L. Giosan, B.G. Valencia, A.M. Folcik, M. Kingston, S. Baskin, M.B. Bush〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A new fossil pollen, 〈em〉Sporormiella,〈/em〉 and sediment chemistry record from Lake Llaviucu, Ecuador, spanning the period from 16,280–9000 years Before Present, provides a high-resolution record of paleoecological change in the high Andes. The deglacial transition from super-páramo through páramo grasslands, to Andean forest is traced, with near-modern systems being established by c. 11,900 years ago. It is suggested that forest elements probably existed in microrefugial populations close to the ice front. 〈em〉Sporormiella〈/em〉 is used as a proxy for megafaunal abundance, and its decline to background levels is inferred to indicate a local extinction event at c. 12,800 years ago. About 1800 years prior to the extinction, charcoal becomes a regular sedimentary component in this very wet valley. An early date for human activity in the valley is suggested, with the direct implication of humans in the extinction of the megafauna.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 21 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Gili Greenbaum, David E. Friesem, Erella Hovers, Marcus W. Feldman, Oren Kolodny〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The transition from the Middle Paleolithic (MP) to the Upper Paleolithic (UP), circa 40kya, is viewed as a major turning point in human evolution, in terms of the material culture, demography, and geographical expansion of modern humans. However, attempts to identify an origin of this so-called ‘revolution’ in the form of a particular stone-tool techno-complex, representing cultural modernity, which spread across the human range, have failed. Instead, the archaeological record of this period comprises multiple ‘transitional techno-complexes’, some associated with modern humans and others with Neanderthals. The cultures that these techno-complexes represent are characterized by precursors of the material cultures of the UP, often alongside features that suggest local cultural continuity. The broadly simultaneous appearance of these transitional cultures, despite a lack of a clear common origin, is puzzling. We suggest that these local ‘revolutions’ had a common underlying driver, which explains the simultaneous appearance of transitional techno-complexes, but that this driver did not determine the particular form of each local revolution. We propose that the driver of the transition to the UP was an increase in inter-population connectivity, both within- and between-species, which allowed local cultures to rapidly evolve and to attain greater complexity than ever before. We suggest that this change was driven by the interaction between modern humans and Neanderthals. In this article we outline processes that are likely to have influenced inter-population connectivity, bringing together evolutionary and ecological perspectives alongside insights from the field of cultural evolution.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 205〈/p〉 〈p〉Author(s): S. Nomade, F. Bassinot, M. Marino, Q. Simon, F. Dewilde, P. Maiorano, G. Isguder, D. Blamart, A. Girone, V. Scao, A. Pereira, F. Toti, A. Bertini, N. Combourieu-Nebout, M. Peral, D.L. Bourlès, P. Petrosino, S. Gallicchio, N. Ciaranfi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Understanding millennial and sub-millennial climate variability during past low eccentricity interglacials similar to the Holocene is important for forecasting the evolution of climate and natural variability. The 〈em〉Ideale section〈/em〉 (Montalbano Jonico, Southern Italy) studied here provides one of the best records of MIS 19c, the closest orbital analog to the Holocene. This exposed marine series covers Termination IX to the inception of MIS 18 with very high sedimentation rates (i.e. 90–200 cm/ka). We present 1) benthic δ〈sup〉18〈/sup〉O and δ〈sup〉13〈/sup〉C records at 90–200 year time-resolution, 2) a new 〈sup〉40〈/sup〉Ar/〈sup〉39〈/sup〉Ar age of 774.1 ± 0.9 ka for tephra layer V4 (Matuyama-Brunhes transitional period) and 3) new calcareous plankton, palynological and authigenic 〈sup〉10〈/sup〉Be/〈sup〉9〈/sup〉Be data. Our new Bayesian depth-age model suggests a 11.5 ± 3.4 ka (95% confidence) duration for the climatic optimum. The δ〈sup〉18〈/sup〉O series reveals millennial-scale oscillations (with sharp transitions 〈 200 years) between ∼774.0 and the onset of MIS 18 (∼757.0 ka) with a cyclicity of about 5.4 ka. Spectral analysis and band-pass filtering indicate that these climate oscillations existed throughout the entire MIS 19 period, although they were dampened during MIS 19c, which is chiefly controlled by orbitally-driven insolation. The amplitude of those sub-orbital oscillations increased towards MIS 18 as the climate became drier and cooler. The Ideale section reveals, with unprecedented detail, millennial-scale climatic oscillations of MIS 19b-a that have been observed worldwide. They highlight the response of the central Mediterranean area to North Atlantic climatic variation (i.e. oceanic circulation and atmospheric processes related to ice-sheet dynamics) during this low eccentricity interglacial.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0277379117310132-fx1.jpg" width="329" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 205〈/p〉 〈p〉Author(s): Jon Camuera, Gonzalo Jiménez-Moreno, María J. Ramos-Román, Antonio García-Alix, Jaime L. Toney, R. Scott Anderson, Francisco Jiménez-Espejo, Jordon Bright, Cole Webster, Yurena Yanes, José S. Carrión〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A new sediment core from Padul, Padul-15-05, provides a long and continuous sedimentary and paleoenvironmental record of the last ∼200 kyr. Here we present a detailed palynological study from this sedimentary sequence with new vegetation and paleoenvironmental data and a climatic interpretation for the last two climatic cycles from the southern Iberian Peninsula in the western Mediterranean region. Pollen analysis from this core shows orbital-scale vegetation oscillations (mainly forced by precession and eccentricity) pointing into insolation as the principal factor controlling vegetation changes at this latitude. The last two glacial-interglacial cycles (from MIS 6 to the present) as well as stadial and interstadial phases are well represented and characterized by significant oscillations in Mediterranean forest in the area, but several differences with respect to other Mediterranean long pollen records can be recognized. Some of these disparities between regions seem to be more related to different precipitation rates linked to the specific geographical features (e.g. strong topographic relief) than to latitudinal differences between the sites. In addition, a lake level reconstruction based on palynological data was developed and compared with the previous reconstruction from this record, representing local environmental changes in the Padul wetland that seems to be related to precipitation/evapotranspiration balance, and therefore, to changes in regional climate conditions. During glacial/stadial conditions recorded by maxima in xerophytes, the p/e increased due to very low evapotranspiration, resulting in high lake levels, while during warmer interglacial/interstadial phases (except for the MIS 5e), mainly represented in this record by maxima in the Mediterranean forest, water level decreased as a result of high evapotranspiration exceeding precipitation input. The comparison of the new Padul-15-05 pollen record with the two previous palynological studies from Padul shows significant differences mainly due to disagreements in the age control of the sequences. This study shows that an accurate age-depth model becomes essential when interpreting long paleoenvironmental and paleoclimate records.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 205〈/p〉 〈p〉Author(s): Margarita Caballero, Socorro Lozano-García, Beatriz Ortega-Guerrero, Alexander Correa-Metrio〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Diatom-based transfer functions for salinity, precipitation and temperature were developed using a training set that included data from 40 sites along central Mexico. These transfer functions showed good performance parameters and were subsequently applied to the previously published diatom record from lake Chalco, southern Basin of Mexico. Heinrich stadials (HS-3 to HS-0) were reconstructed as cold and dry events, with HS-2 representing the coldest and driest conditions, while HS-1 shows a complex bimodal cooling pattern. Orbital scale variability is also recorded. High and variable lake salinities from ∼34 to 29 ka BP (marine isotope stage 3, MIS-3) corresponded with times of maximum summer insolation and evidences of frequent fires. MIS-2 was identified as a cold period, with low lake salinity associated with low evaporation, with two cold intervals during the minima in spring (∼25.5 ka BP) and summer (∼20 ka BP) insolation. The ∼20 ka BP cold event together with HS-2 (24-23 ka BP), defined a bimodal maximum cooling during the last glacial maximum (LGM: 24.5–19.5 ka BP) within the range of pollen-based estimates, further supporting a maximum tropical cooling of 4–5 °C for the LGM. The deglacial (19.5–11.5 ka BP) showed the highest precipitation anomalies with three peaks that closely correlated with glacier advances in the nearby mountains (Iztaccihuatl). The early Holocene marked a change towards high lake salinities and the highest positive temperature anomalies (+3.5 °C) during a peak in summer insolation. Even though at orbital scale Chalco showed a nearly opposite trend to the record from the more southerly lake Peten-Itza (Guatemala), at millennial scale it showed a common pattern of cold and dry conditions during HSs, comparable to other tropical latitude sites in the northern hemisphere and further supporting the idea that there is a strong coupling between tropical and higher latitudes climates, in particular with the North 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): Virgil Pasquier, Samuel Toucanne, Pierre Sansjofre, Yama Dixit, Sidonie Revillon, Zohra Mokeddem, Marina Rabineau〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study we use bulk sediment organic matter stable isotopes (δ〈sup〉13〈/sup〉C〈sub〉org〈/sub〉 and δ〈sup〉15〈/sup〉N) to examine the nature and timing of preserved organic matter in borehole PRGL1-4 from Northwestern Mediterranean Sea. This region is known as a transitional zone between the North Atlantic atmospheric circulation and the North African monsoon system. In the Gulf of Lion (SE France), increased inputs of organic matter from sediment-laden rivers occurred during warm substages of the last 200 kyr (MIS 5e, 5c, and 5a; MIS 6d, and 6b). Increased terrestrial organic matter are inferred from organic carbon isotopic composition (δ〈sup〉13〈/sup〉C〈sub〉org〈/sub〉), and are interpreted as resulting from enhanced rainfall over the Rhone river catchment area. Such increase in terrestrial organic carbon induced enhancement of the primary productivity leading to the formation of local oxygen minimum zone as demonstrated by ∼3‰ values in δ〈sup〉15〈/sup〉N. Comparison with regional paleohydrological records from the northern Mediterranean borderlands reveals the regional character of these pluvial events. Taking advantage of the location of PRGL1-4 borehole, out of Mediterranean cyclogenesis area, we suggest that the pluvial events recorded during warm substages of the last 200 kyr occurred in response to enhanced passage of North Atlantic atmospheric perturbation over the Gulf of Lion catchment area (especially over Rhone river watershed which represent 80% of the GoL catchment area), a scenario possibly similar to that encountered today during negative- NAO like conditions. At a regional scale, our data suggests that high rainfall events over the Gulf of Lion catchement area and the Rhone watershed occurred at the time of North African summer monsoon and the sapropel deposition in the Mediterranean basin, thus highlighting a close coupling between mid- (North Atlantic) and low-latitudes (monsoon) climate systems. Importantly, our geochemical evidence from the Gulf of Lion support an extra-Mediterranean source for the regional pluvial events described in many paleoclimatic records from the northern Mediterrean borderlands during warm substages of the last climate cycles. Consequently, we suggest that this region as a whole could provide, in addition to the river runoff from the North African sector, the necessary conditions for the sapropel deposition.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 205〈/p〉 〈p〉Author(s): Mónika Tóth, Maarten van Hardenbroek, Niels Bleicher, Oliver Heiri〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉At waterlogged archaeological sites paleolimnological approaches can provide important supporting information about conditions and processes of past human life and human impact on environments around former settlements. In this study, subfossil Cladocera and Chironomidae assemblages were analysed from Neolithic lakeside sediments uncovered at Zürich-Parkhaus Opéra (OP), Switzerland. Our main objectives were to assess how periodic settlement phases altered lakeshore environments and aquatic invertebrate communities during the Neolithic. Aquatic invertebrates occurred in considerable numbers throughout the investigated sediment sections, supporting that Neolithic settlements at site OP were established above the lake surface and sedimentation occurred mostly under water. Two separate aquatic invertebrate communities were distinguished: an impacted community within cultural layers and a pre- and post-impacted community in sediments above, below and in between cultural layers. Aquatic invertebrates indicated that human impact likely resulted in surplus organic material load and nutrient input into the water during the cultural periods. This substantially increased biological oxygen demand of the sediments and overall nutrient concentrations of the near-shore water and thereby led to hypoxic conditions. Chironomids showed generally higher amplitude assemblage changes than cladocerans. This could be explained by the very local influence of humans and higher susceptibility of the less mobile chironomids to local hypoxia in and above the sediment. After settlements were abandoned invertebrate assemblages rapidly recovered to pre-impacted states, suggesting their considerable resilience to local human impact. Our results confirm that cladoceran and chironomid remains can trace localised environmental changes associated with human presence and provide important information for the interpretation of prehistoric human activities.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 22 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Slimak Ludovic〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The chronological and territorial expansion of neandertalian societies, their capacities of adaptation and expansion, show that their brutal extinction, which not only affects their ways of life but also their biological reality, cannot be rationally imputed to a natural process. As a result, we here propose that theories addressing these extinctions through these prisms cannot account for the adaptive ubiquity of these societies, or for the vast territories on which these groups settled. It appears more than ever essential to look for the processes in question in relation with thei cultural anthropology of the concerned societies. Neandertal extinction remains a purely speculative scientific field, but considering the remarkable adaptative abilities revealed by these populations, we assume on our own that climatic change, modification to environments, disappearance of traditionally hunted fauna or a subtle combination of all of these causes would thus be considered as extremely secondary in that extinction process. These factors, whose only limits are the imagination of researchers, who are distant spectators of this replacement, cannot account for the primary processes of this hominin disappearance.〈/p〉 〈p〉The approach angle is considered here as a presupposition, yet research as a discipline does not require the alignment of concepts developed by researchers but rather the demonstration of their logical constructs. Should this process be above all, not to say exclusively, approached from the point of view of the history and the sociology of these past societies? How can we understand that, after 150 years of archaeology, one of the most recent and most important hominin extinction remains focused in the Natural Sciences sphere, with no fundamental construction of a Cultural Anthropology of the last Neanderthals?〈/p〉 〈p〉More deeply, we must investigate the ethological and anthropological structures of these populations. Does a Neanderthalian ethology ever existed? The question of the identification of an ethology of biologically fossil societies cannot be evaluated on the notions of presence/absence of archaeological realities to which we subjectively confer a discriminating function (a bone tool, an ornament, a grave, - … -), but by exploring the logical identification of all the technical and cultural products of these societies. These heuristic paths are promising and still have to be scientifically explored.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 204〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 205〈/p〉 〈p〉Author(s): Daniel Charters, Grégory Abrams, Isabelle De Groote, Kévin Di Modica, Dominique Bonjean, Carlo Meloro〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The supposed herbivorous cave bear (〈em〉Ursus spelaeus〈/em〉) occupied Europe throughout the Quaternary. Being subject to large spatial variation has led to the intensive study on its geographical polymorphism, generating debates on sub-speciation. However, temporal morphological information on the species is somewhat lacking. Here, we apply geometric morphometrics (GMM) technique to investigate temporal morphological variation in molar size and shape of 〈em〉Ursus spelaeus〈/em〉 from different chronostratigraphic sediment units in a geographically confined site (Scladina Cave, Belgium), covering approximately 100,000 years.〈/p〉 〈p〉Our findings show significant morphological variation between groups analysed in both size and shape. M〈sup〉2〈/sup〉 shows a chronological size increase with PCA plots visually expressing differences in all groups, relating to a buccolingual expansion and an increase of the talon masticatory platform through time. Reduction in the M〈sup〉1〈/sup〉 is also shown, possibly to maintain biomechanical performance of dentition for effective mastication, more so in groups relating to the latter stages of the Quaternary.〈/p〉 〈p〉Findings suggest a rapid response to climatic factors constraining consumable food sources, with GMM offering a promising analytical approach in understanding the palaeobiology, palaeoecology and morphological variation in extinct and extant fossil mammals.〈/p〉 〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0277379118305699-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 205〈/p〉 〈p〉Author(s): Ruibo Zhang, Wenshou Wei, Huaming Shang, Shulong Yu, Xiaohua Gou, Li Qin, Kainar Bolatov, Bulkajyr T. Mambetov〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Fluctuations in glacier mass and volume are indicative of changes in the climate system. They also strongly affect regional climate and hydrology. In this paper, we explore possible relationships between the radial growth of Schrenk spruce (〈em〉Picea schren〈/em〉kiana Fisch. et Mey) and the mass balance of the Tsentralniy Tuyuksuyskiy (TS. Tuyuksuyskiy) Glacier, which is located on the northern slopes of the Tianshan Mountains in arid central Asia. We attempt to reconstruct the historical mass balance variability of the TS. Tuyuksuyskiy glacier using tree-ring widths and stable carbon isotope chronologies. The reconstruction is able to explain 62.1% of the variance in the annual glacier mass balance record over the 1965–2014 calibration period. We also analyzed centennial mass balance variability and its linkages to climate change. The TS.Tuyuksuyskiy glacier has a negative annual mass balance in most years and, since 1968, has undergone the most rapid and longest melting process in the past 166 years. The mass balance change of the glacier is controlled by the combination of temperature and precipitation conditions. This study could be useful for more detailed glaciological, hydrological, and climatological assessments in this portion of the Tianshan Mountains.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 204〈/p〉 〈p〉Author(s): Ny Riavo G. Voarintsoa, Ilkka S.O. Matero, L. Bruce Railsback, Lauren J. Gregoire, Julia Tindall, Louise Sime, Hai Cheng, R. Lawrence Edwards, George A. Brook, Gayatri Kathayat, Xianglei Li, Amos Fety Michel Rakotondrazafy, Marie Olga Madison Razanatseheno〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The 8.2 ka event is a well-known cooling event in the Northern Hemisphere, but is poorly understood in Madagascar. Here, we compare paleoclimate data and outputs from paleoclimate simulations to better understand it. Records from Madagascar suggest two distinct sub-events (8.3 ka and 8.2 ka), that seem to correlate with records from northern high latitude. This could indicate causal relationships via changes in the Atlantic Meridional Overturning Circulation (AMOC) with changes in moisture source's δ〈sup〉18〈/sup〉O, and changes in the mean position of the Inter-Tropical Convergence Zone (ITCZ), as climate modelling suggests. These two sub-events are also apparent in other terrestrial records, but the climatic signals are different. The prominent 8.2 ka sub-event records a clear antiphase relationship between the northern and southern hemisphere monsoons, whereas such relationship is less evident during the first 8.3 ka sub-event. Data–model comparison have also shown a mismatch between the paleoclimate data and the model outputs, the causes of which are more or less understood and may lie in the proxies, in the model, or in both data and model. Knowing that paleoclimate proxies and climate models produce different sets of variables, further research is needed to improve the data–model comparison approach, so that both paleoclimate data and paleoclimate models will better predict the likely climate status of a region during a specified time in the past with minimal uncertainties.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 204〈/p〉 〈p〉Author(s): Patrick De Deckker, Lee J. Arnold, Sander van der Kaars, Germain Bayon, Jan-Berend W. Stuut, Kerstin Perner, Raquel Lopes dos Santos, Ryu Uemura, Martina Demuro〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Over the last four decades of palaeoclimate research, significant emphasis has been placed on the Last Glacial Maximum (LGM) spanning 26.5–19 thousand years ago (ka), a period that saw significant (∼125 m) sea-level reductions and major ice caps adorning large parts of the Northern Hemisphere. Here, we present evidence for another major glacial period spanning 71–59 ka (Marine Isotope Stage 4: MIS4) from a well-dated marine sequence offshore South Australia. The astronomically-tuned chronology of this deep-sea core is confirmed using single-grain optically stimulated luminescence dating (OSL), providing confidence in our high-resolution age model. Our approach to the study of our MD03-2607 core has been to employ many different proxies. These are: δ〈sup〉18〈/sup〉O of both planktic and benthic foraminifera for stratigraphic purposes, faunal counts of planktonic foraminifera to reconstruct the position of oceanic fronts and currents, alkenone palaeothermometry, XRF core scanning to determine the presence of aeolian dust, and εNd isotope to identify fluvial discharge over the core site. We compare our new proxy findings with other archives for mainland Australia and Tasmania.〈/p〉 〈p〉Our multi-proxy palaeoclimate reconstructions are consistent with other marine, terrestrial and cryosphere archives across the Southern Hemisphere and suggest, for the first time, that MIS 4 was almost as dramatic as the LGM. During MIS4, global sea-level was reduced by ∼100 m, glaciers across Australasia were more significant compared to the LGM, and sea-surface temperatures were much reduced. These glacial conditions uniformly peaked around 65 ka. Global comparisons show major glacial conditions and vegetation shifts elsewhere during MIS4, but many are poorly dated. The significant environmental changes taking place during this glacial period were paralleled by waves of human dispersal across Eurasia and the earliest evidence of human occupation in northern Australia at 65 ka.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 200〈/p〉 〈p〉Author(s): Timothy A. Shaw, Andrew J. Plater, Jason R. Kirby, Keven Roy, Simon Holgate, Pero Tutman, Niamh Cahill, Benjamin P. Horton〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Differential tectonic activity is a key factor responsible for variable relative sea-level (RSL) changes during the late Holocene in the Adriatic. Here, we compare reconstructions of RSL from the central-eastern Adriatic coast of Croatia with ICE-7G_NA (VM7) glacial-isostatic model RSL predictions to assess underlying driving mechanisms of RSL change during the past ∼ 2700 years. Local standardized published sea-level index points (n = 23) were combined with a new salt-marsh RSL reconstruction and tide-gauge measurements. We enumerated fossil foraminifera from a short salt-marsh sediment core constrained vertically by modern foraminiferal distributions, and temporally by radiometric analyses providing sub-century resolution within a Bayesian age-depth framework. We modelled changes in RSL using an Errors-In-Variables Integrated Gaussian Process (EIV-IGP) model with full consideration of the available uncertainty. Previously established index points show RSL rising from −1.48 m at 715 BCE to −1.05 m by 100 CE at 0.52 mm/yr (−0.82-1.87 mm/yr). Between 500 and 1000 CE RSL was −0.7 m below present rising to −0.25 m at 1700 CE. RSL rise decreased to a minimum rate of 0.13 mm/yr (−0.37-0.64 mm/yr) at ∼1450 CE. The salt-marsh reconstruction shows RSL rose ∼0.28 m since the early 18th century at an average rate of 0.95 mm/yr. Magnitudes and rates of RSL change during the twentieth century are concurrent with long-term tide-gauge measurements, with a rise of ∼1.1 mm/yr. Predictions of RSL from the ICE-7G_NA (VM7) glacial-isostatic model (−0.25 m at 715 BCE) are consistently higher than the reconstruction (−1.48 m at 715 BCE) during the Late Holocene suggesting a subsidence rate of 0.45 ± 0.6 mm/yr. The new salt-marsh reconstruction and regional index points coupled with glacial-isostatic and statistical models estimate the magnitude and rate of RSL change and subsidence caused by the Adriatic tectonic framework.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 200〈/p〉 〈p〉Author(s): Bernd Wünnemann, Dada Yan, Nils Andersen, Frank Riedel, Yongzhan Zhang, Qianli Sun, Philipp Hoelzmann〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The influence of the mid-latitude westerlies (MLW) competing with the Asian summer monsoons (ASM) over the Tibetan Plateau (TP) remains a matter of discussion on how and to which extent both atmospheric systems have been controlling hydro-climate during the Holocene. Depleted oxygen isotopes in lake deposits were commonly interpreted in terms of enhanced summer monsoon moisture supply, implying a migration of the ASM deep into the interior of the plateau during Holocene periods. In order to test this relationship we used a high resolution oxygen isotope record (mean 20 yr resolution) in combination with carbonates and mineral phases, titanium flux, grain size and ostracod abundances derived from a 6.84 m long sediment core in the endorheic Kuhai Lake basin, north-eastern TP. The results confirm 1) continuous positive co-variance between enriched δ〈sup〉18〈/sup〉O〈sub〉carb〈/sub〉 and total carbonates during the last 14 ka, indicative of dominant seasonal influence on multi-decadal to centennial scale isotopic signatures in lake water and respective carbonate precipitation, 2) negative co-variance between allochthonous sediment flux and δ〈sup〉18〈/sup〉O〈sub〉carb〈/sub〉 (and carbonates) attributed to relative increase of flux rates during non-summer seasons, 3) correspondence of lake level variations with carbonate mineral phases and the occurrence/disappearance of ostracod assemblages, and 4) inverse relationships between isotopic signatures in ASM-dominated and MLW-controlled lake records across the TP. Enriched δ〈sup〉18〈/sup〉O〈sub〉carb〈/sub〉 in Kuhai Lake sediments was primarily a result of high evaporation during the summer seasons, while ASM-related rainfall amount did not play an important role, likely counterbalanced by isotopic signatures from different water sources. Conversely, depleted δ〈sup〉18〈/sup〉O〈sub〉carb〈/sub〉 was mainly attributed to water supply during non-summer seasons of colder temperatures and generally light isotopic signatures from MLW-derived sources. This finding may lead to a paradigm shift in such way that depleted δ〈sup〉18〈/sup〉O in carbonates is primarily not the result from ASM-related rainfall as previously assumed. The reconstructed hydro-climatic history of Kuhai Lake indicates the dominance of westerly-derived climate during the Younger Dryas interval (12.8–11.5 ka) under very shallow pond-like conditions. Despite climate amelioration during the early Holocene (11.5–7.5 ka) hydrological conditions remained unstable with frequent alternations between dominance of summer and winter seasons. During the middle Holocene (7.5–5.5 ka) the lake experienced highest lake levels dominated by summer monsoon-related water supply, assigned to the Holocene hydro-climatic optimum. Frequent high-amplitude fluctuations afterwards (5.1–2.9 ka) refer to cooling/drying events under enhanced MLW influence accompanied by a strong lake level decline. The late Holocene (2.9 ka- Present) period experienced moderate isotopic variations and fluctuating lake levels in response to variable influence of summer- or winter-related hydro-climatic conditions.〈/p〉 〈p〉This seesaw-like pattern with amplitudes of 〉10‰ in δ〈sup〉18〈/sup〉O〈sub〉carb〈/sub〉 resembles fluctuations in cave records and variations between air and seawater (Dole effect). High correspondence with cooling events derived from North Atlantic drift ice and meltwater discharge indicate close ties to northern hemispheric climate transmitted by the MLW across the TP.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 200〈/p〉 〈p〉Author(s): Mauro Cremaschi, Michele Degli Esposti, Dominik Fleitmann, Alessandro Perego, Emanuela Sibilia, Andrea Zerboni〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper discusses the time and steps of the introduction of intensive agriculture and evolution of irrigation systems to sustain crops in the palaeo-oasis of Salut in the northern Sultanate of Oman. Various geoarchaeological methods allow reconstructing the exploitation of the natural resources of the region and technological development of irrigation methods since the Mid-Holocene. Intensive agriculture started during the Bronze Age and continued with some spatial and intensity fluctuations up to the Islamic period. Cultivations were initially sustained by surface irrigation systems and later replaced by a dense net of aflaj, the typical surface/underground system adopted in the Levant, Arabian Peninsula and western Asia to collect water from deep piedmont aquifers and redistribute it to the fields located in the lowlands. Our results indicate that the aflaj were in use for a long period in the palaeo-oasis formed along Wadi Sayfam and surrounding the citadel of Salut. Uranium-Thorium dating of calcareous tufa formed in the underground tunnels of the aflaj suggests that they were used between ∼540 BCE and ∼1150 CE. After ∼1150 CE Wadi Sayfam were abandoned and the size of the oasis shrank substantially. During the late Islamic period, a surface aqueduct descending from the piedmont of Jabal Shams secured water supply. Our work confirms that in arid lands archaeological and historical communities were able to actively modulate their response to climate changes by using a variety of technological strategies.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 200〈/p〉 〈p〉Author(s): S.P. Obrochta, Y. Yokoyama, M. Yoshimoto, S. Yamamoto, Y. Miyairi, G. Nagano, A. Nakamura, K. Tsunematsu, L. Lamair, A. Hubert-Ferrari, B.C. Lougheed, A. Hokanishi, A. Yasuda, V.M.A. Heyvaert, M. De Batist, O. Fujiwara, the QuakeRecNankai Team〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An 8000-year lacustrine sediment record from Lake Motosu (Fuji Five Lakes) records several eruptions, including potentially unreported events, of the active Mt. Fuji volcano, which receives approximately 47 million annual visitors. A high-fidelity age model is constructed from tephra ages and high-density radiocarbon dating of terrestrial macrofossil and bulk organic matter. Variability in lake reservoir age is constrained by modern lake water radiocarbon measurement and reverse calibration of tephra calendar ages. We present more accurate ages for known eruptions, detect a wider distribution of ejecta for several eruptions, including the most recent summit eruption, and potentially identify previously undetected flank eruptions. There are closely spaced scoria-fall layers that may be difficult to differentiate as separate events in land-based surveys. These results demonstrate the utility of lacustrine sediments as powerful tools for understanding characteristics of volcanic eruptions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 200〈/p〉 〈p〉Author(s): Polina Vakhrameeva, Andreas Koutsodendris, Sabine Wulf, William J. Fletcher, Oona Appelt, Maria Knipping, Ralf Gertisser, Mario Trieloff, Jörg Pross〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Precise chronologies that allow direct correlation of paleoclimate archives are a prerequisite for deciphering the spatiotemporal characteristics of short-term climate variability. Such chronologies can be established through the analysis of tephra layers that are preserved in the respective sedimentary archives. Here we explore the yet untapped tephrochronological potential of the Eastern Mediterranean region for the Middle Pleistocene, specifically for the interval spanning Marine Isotope Stages (MIS) 12–10 (460–335 ka). High-resolution cryptotephra analysis was carried out on peat cores spanning the MIS 12–10 interval that have been recovered from the iconic climate archive of Tenaghi Philippon, NE Greece. Eighteen primary cryptotephras were identified, and major- and trace-element analyses of single glass shards from all cryptotephras were performed in order to correlate them with their eruptive sources. The results suggest origins from both Italian and Aegean Arc volcanoes. Specifically, one cryptotephra layer could be firmly correlated with the Cape Therma 1 eruption from Santorini, which makes it the first distal tephra finding for this eruptive event. While eight further cryptotephras could be tentatively correlated with their volcanic or even eruptive sources, the provenance of another nine cryptotephras as yet remains unknown. The relatively large number of cryptotephras that could not be assigned to specific volcanic sources and eruptive events reflects the still considerable knowledge gap regarding the geochronology and geochemistry of proximal tephra deposits from the Middle Pleistocene of the Central and Eastern Mediterranean regions. Due to the lack of well-dated Middle Pleistocene eruptions, we provide age estimates for all cryptotephra layers identified in the MIS 12–10 interval at Tenaghi Philippon based on high-resolution pollen data from the same cores. While eight of the identified cryptotephras were deposited within MIS 12 (∼438–427 ka), one cryptotephra was deposited at the onset of MIS 11 (∼419 ka), five cryptotephras during the younger part of MIS 11 (∼391–367 ka), and four cryptotephras during MIS 10 (∼359–336 ka). The high number of cryptotephras from multiple sources as recorded in the MIS 12–10 interval at Tenaghi Philippon highlights the key role of this archive for linking tephrostratigraphic lattices for the Middle Pleistocene of the Central and Eastern Mediterranean regions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 200〈/p〉 〈p〉Author(s): Piotr Kołaczek, Mateusz Płóciennik, Mariusz Gałka, Karina Apolinarska, Kamila Tosik, Michał Gąsiorowski, Stephen J. Brooks, Monika Karpińska-Kołaczek〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, we focus on the environmental changes recorded in the San River valley (Stubno–Nakło site, south-eastern Poland) at the beginning of the Holocene. This multi-proxy study for the first time in the region of the northern foreland of the Western Carpathians included quantitative thermal reconstruction based on Chironomidae and high-stratigraphic resolution of 〈sup〉14〈/sup〉C AMS dating. We hypothesised that (i) climate events during the Early Holocene contributed to ecosystem turnovers via stimulating disturbances related to the river's fluvial activity and (ii) woodland and oxbow lake ecosystems became more resilient to flood disturbances along with the advance of forest succession on the floodplain. The results revealed that the response of ecosystems on the Early Holocene warming was strongly linked with the decrease in fluvial activity of the river. The reconstruction of the mean July temperature based on Chironomidae revealed the exceptionally high rate of warming during the period of ca. 11,490–11,460 cal. BP (at least 1 °C per decade) up to values 〉 2 °C than modern ones. During this period, the lake trophy and productivity started to increase with a simultaneous spread of 〈em〉Betula〈/em〉 woodlands on the alluvial plain. The “Preboreal oscillation” cooling was dated at ca. 11,450–11,250 cal. BP. At that time, an increased climate instability led to a higher rate of extremal events such as flood at ca. 11,400–11,330 cal. BP, which probably led to the disruption of the 〈em〉Betula〈/em〉 population. The development of riparian woodlands, initiated by the expansion of 〈em〉Ulmus〈/em〉 from ca. 11,100 cal. BP, and further spread of 〈em〉Quercus〈/em〉 and 〈em〉Fraxinus excelsior〈/em〉 on the alluvial plain and lower river terraces increased plant transpiration and therefore limited the river runoff and its fluvial activity. This, together with the expansion of reed belt communities, probably limited the impact of floods on the oxbow lake. However, ca. 10,010–9880 cal. BP traces of higher fluvial activity, but of lower impact, were recorded.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 199〈/p〉 〈p〉Author(s): Judith Z. Drexler, Christopher C. Fuller, Stacey Archfield〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The peak fallout in 1963 of the radionuclide 〈sup〉137〈/sup〉Cs has been used to date lake, reservoir, continental shelf, and wetland sedimentary deposits. In wetlands such dating is used to project the ability of wetlands to keep pace with sea level rise and develop strategies for mitigating carbon pollution using biological carbon sequestration. Here we demonstrate that reliable 〈sup〉137〈/sup〉Cs profiles are increasingly difficult to obtain from wetland soils. Among 58 soil cores recently collected from a range of wetland types and 〈sup〉137〈/sup〉Cs fallout densities across the United States, 25% contain no identifiable 〈sup〉137〈/sup〉Cs peaks. Less than 40% of 〈sup〉137〈/sup〉Cs ages are consistent with 〈sup〉210〈/sup〉Pb dating. We provide a new measure of 〈sup〉137〈/sup〉Cs peak clarity (τ) for our core dataset by comparing the 50% interquartile range of data around the 〈sup〉137〈/sup〉Cs peak for “ideal” cores profiles determined using 〈sup〉137〈/sup〉Cs fallout data to that of observed core profiles. Our results show that overall τ is approximately 10 times greater for observed cores than ideal cores. The deterioration in the 〈sup〉137〈/sup〉Cs peak has occurred due to radionuclide decay, 〈sup〉137〈/sup〉Cs migration 〈em〉in situ〈/em〉, which is ubiquitous in this study, and 〈sup〉137〈/sup〉Cs amendments from surface waters. Such deterioration likely extends to both Mexican and non-permafrost, Canadian wetlands. We recommend continued use of 〈sup〉137〈/sup〉Cs 〈em〉only〈/em〉 if the full bound of dating uncertainty for both 〈sup〉137〈/sup〉Cs and an additional method such as 〈sup〉210〈/sup〉Pb is propagated into estimates of wetland vertical accretion and carbon sequestration.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 199〈/p〉 〈p〉Author(s): Mulugeta Mokria, Aster Gebrekirstos, Abrham Abiyu, Achim Bräuning〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Nile River is one of the principal rivers in Africa, with Blue Nile (BNRiF) and Tekeze-Atbara (TARiF) rivers being its largest tributaries. However, long-term hydrological information is lacking in the Nile basin, which is a shortcoming to design and implement sustainable water management. We reconstructed river discharge since A.D. 1784 using tree-ring proxy data to (1) extend the short existing discharge records (2) examine long-term flow variability, and (3) identify characteristics of high- and low-flow periods and their connection with large-scale climate forcing factors like the El Niño–Southern Oscillation (ENSO) and Indian Ocean Dipole Mode (IOD). The chronology (RPC#1) correlates significantly with annual BNRiF (r = 0.62, 〈em〉p〈/em〉 〈 0.001) and TARiF (r = . 66, 〈em〉p〈/em〉 〈. 001) discharge. Reconstructed river discharge showed significant high-frequency variations at 2- to 4-year cycles, and sub-decadal and decadal periodicities at 7–10 and 10–14 years, respectively. The inter-annual discharge deviations from the mean during pluvial (dry) periods reached up to 38% (−32%) in BNRiF and 76% (−65%) in TARiF. El Niño and La Niña events matched with 40% and 59% of extreme-dry and extreme-pluvial episodes, indicating teleconnections influencing the regional rainfall and hydrological system. Reconstructed river discharge showed significantly positive spatial relationships with rainfall and negative spatial correlations with temperature across northern Ethiopia and large parts of the Sahel belt and the White Nile swamps in South Sudan. The short instrumental period did not adequately represent the full range of annual to multidecadal discharge variability present in the reconstruction. Hence, the data presented are crucial to extend hydrological records and to revise existing worst-case scenarios and water management strategies developed based on short instrumental records for water supply and energy production across the Nile basin.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 20 September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Jack H. Lacey, Matthew D. Jones〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We investigate the modern hydrology of Lake Ohrid (Macedonia/Albania) using a combined hydrological and isotope-based modelling approach and present a new evaluation of contemporary water balance and palaeoclimate estimates. The combined model is able to estimate hydrological components that cannot be directly measured, and indicates that sublacustrine spring inflow is in the order of 50% higher than previous estimates and groundwater outflow comprises approximately a third of overall water outflow. In combination with sediment core oxygen isotope data, we used the combined model to quantitatively reconstruct past climate, in particular precipitation, during the early Holocene and last glacial period. Calculated precipitation in the early Holocene was higher than the value for present day and was approximately 44% lower than present during the last glacial, assuming the majority of precipitation fell as snow. The estimated amount of precipitation in the last glacial would have been high enough to provide refugial conditions at Lake Ohrid and to support the continuous existence of arboreal vegetation in the catchment. The improved understanding of the modern isotope hydrology of Lake Ohrid is fundamental for explaining the systematics of past isotope variation and providing context for extended sediment records from the lake, which will provide longer-term palaeoclimate reconstructions covering multiple glacial-interglacial cycles.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 200〈/p〉 〈p〉Author(s): Kirsten M. Menking, Victor J. Polyak, Roger Y. Anderson, Yemane Asmerom〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Newly acquired U〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Th dates on gypsum sands contained within Pleistocene lake sediments allow us to extend the record of climatic change in the Estancia Basin of central New Mexico back to ∼69 ka from a previous limit of ∼29 ka. Using a hydrologic balance index (HBI) that reflects variations in sediment mineralogy and bedding characteristics, we find strong similarities to speleothem oxygen isotopic records for the southwestern United States as well as to isotopic variations in Greenland ice cores. Intervals of wetter climate in the Estancia Basin generally appear to correlate to colder conditions in the North Atlantic and conversely. The existence of a pronounced dry period from 18.1 to 17 ka matches in timing the Extrapolar Climate Reversal of Asmerom et al. (2017) at Fort Stanton cave in southern New Mexico and confirms a different origin for this stadial-like event. Furthermore, the new U〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Th dates support the existing Estancia Basin interpretation of a dry Bølling/Allerød followed by a wet Younger Dryas, a result consistent with speleothem and wet meadow evidence from New Mexico and Arizona (Asmerom et al., 2010, 2017; Polyak et al., 2004; Hall et al., 2012; Wagner et al., 2010) but in conflict with an interpretation of speleothem evidence from central Texas (Feng et al., 2014).〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 200〈/p〉 〈p〉Author(s): C.A. Geoffroy, B.V. Alloway, À. Amigo, M.A. Parada, F. Gutierrez, A. Castruccio, N.J.G. Pearce, E. Morgado, P.I. Moreno〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉We describe the stratigraphy, age, constituent geochemistry and phenocryst thermobarometry of a closely spaced Holocene tephra couplet from Volcán Melimoyu (VMm), located in the Northern Patagonian Andes. The lower tephra unit (La Junta Tephra, Mm-1) is distinctly banded comprising a dominant lower layer of rhyodacitic (∼70% SiO〈sub〉2〈/sub〉) pumiceous ash and lapilli (Mm-1p) that abruptly transitions to a subordinate upper scoriaceous layer (Mm-1s) of basaltic andesite composition (∼53% SiO〈sub〉2〈/sub〉). This bimodality within Mm-1 contrasts significantly with the closely overlying Santa Ana Tephra (Mm-2) that has a homogeneous trachyte-dacite (∼63% SiO〈sub〉2〈/sub〉) composition and is intermediate between the two magmatic end members of Mm-1. We propose a genetic affiliation between Mm-1 and Mm-2, and that the latter event likely represents a hybridised-remnant of those discrete magmas involved in the earlier Mm-1 eruption. To test this hypothesis we applied whole rock elemental mixing and fractional crystallisation model to reproduce the composition and crystallinity of Mm-2. Results indicate that Mm-2 can be reproduced by mixing ∼70% Mm-1p with ∼30% Mm-1s, with subsequent ∼13% fractional crystallisation of plagioclase, and minor amphibole, orthopyroxene, magnetite and biotite.〈/p〉 〈p〉Equilibrium P-T conditions calculated from Mm-1p phenocrysts point towards magma residency at moderately shallow depths (200–290 MPa, ∼7–10-km depth, 850–1000 °C), whereas Mm-1s phenocrysts indicate higher overall P-T conditions (240–480 MPa, ∼8.5–17-km depth, 1080–1150 °C). P-T conditions determined for Mm-2 (∼290 MPa, ∼10-km depth, 930–1000 °C) are similar to those of Mm-1p. There is no physical and/or geochemical evidence of mafic magma involvement in the Mm-2 eruption.〈/p〉 〈p〉Similar compositionally bimodal tephra are known from other Northern Patagonian Andean centres (i.e. Playas Blanca-Negra Tephra, Antillanca; Lepue Tephra, Michimahuida; Ho and H3 eruptions of Hudson) suggests that the intrusion of mafic magma into more silicic magma bodies is a common occurrence throughout this Andean sector. These widely dispersed, compositionally bimodal tephra not only provide key insights into pre-eruptive magmatic conditions and triggering processes, but can also be readily identified geochemically, and thereby be more fully utilised within future hazard- and paleoenvironmental-related studies.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 200〈/p〉 〈p〉Author(s): Michael Weber, Denis Scholz, Andrea Schröder-Ritzrau, Michael Deininger, Christoph Spötl, Federico Lugli, Regina Mertz-Kraus, Klaus Peter Jochum, Jens Fohlmeister, Cintia F. Stumpf, Dana F.C. Riechelmann〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Marine Isotope Stage 3 (MIS 3, 57–27 ka) was characterised by numerous rapid climate oscillations (i.e., Dansgaard-Oeschger (D/O-) events), which are reflected in various climate archives. So far, MIS 3 speleothem records from central Europe have mainly been restricted to caves located beneath temperate Alpine glaciers or close to the Atlantic Ocean. Thus, MIS 3 seemed to be too cold and dry to enable speleothem growth north of the Alps in central Europe.〈/p〉 〈p〉Here we present a new speleothem record from Bunker Cave, Germany, which shows two distinct growth phases from 52.0 (+0.8, −0.5) to 50.9 (+0.6, −1.3) ka and 47.3 (+1.0, −0.6) to 42.8 (±0.9) ka, rejecting this hypothesis. These two growth phases potentially correspond to the two warmest and most humid phases in central Europe during MIS 3, which is confirmed by pollen data from the nearby Eifel. The hiatus separating the two phases is associated with Heinrich stadial 5 (HS 5), although the growth stop precedes the onset of HS 5. The first growth phase is characterised by a fast growth rate, and Mg concentrations and Sr isotope data suggest high infiltration and the presence of soil cover above the cave. The second growth phase was characterised by drier, but still favourable conditions for speleothem growth. During this phase, the δ〈sup〉13〈/sup〉C values show a significant decrease associated with D/O-event 12. The timing of this shift is in agreement with other MIS 3 speleothem data from Europe and Greenland ice core data.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 199〈/p〉 〈p〉Author(s): Timo Ruskeeniemi, Jon Engström, Jukka Lehtimäki, Heikki Vanhala, Kimmo Korhonen, Anne Kontula, Lillemor Claesson Liljedahl, Jens-Ove Näslund, Rickard Pettersson〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Greenland Ice Sheet (GrIS) covers an area of 1.7 million km〈sup〉2〈/sup〉. It has been an important source of climate information and the air temperature history of Greenland is well known. However, the thermal history and temperature conditions of the Greenland bedrock are poorly known. There are only few records on the temperature of the proglacial bedrock and no records on bedrock temperature underneath the ice sheet. The Greenland Analogue Project (GAP) recently investigated hydrological, hydrogeological and geochemical processes in Kangerlussuaq, West Greenland. Because permafrost has a major hydrological impact in Arctic regions, the cryogenic structure of the bedrock was an important research topic. From previous studies it was already known that Kangerlussuaq is located within the zone of continuous permafrost. Temperature profiling in a new research borehole, extending horizontally 30 m underneath the ice sheet, revealed that permafrost is 350 m deep at the ice margin. This result raised the question how far the permafrost extends under the ice sheet? In order to investigate the thermal properties, we made a series of electromagnetic (EM) soundings at the ice margin area – on proglacial area and on the ice sheet – and detected, that subglacial permafrost extends at least 2 km from the ice margin to inland. We also observed a patchy unfrozen sediment layer between the ice and the frozen bedrock. Possible existence of subglacial sediments and their role in ice dynamics has been debated in many recent papers. Our successful campaign shows that geophysics can be used for bedrock investigations through thick ice, which is known to be challenging for electromagnetic methods. Our results provide the first direct evidence supporting the proposed Holocene ice re-advance over frozen ground, and contribute to the discussion on the rapid climate changes in past, to the future of the ice sheet under warming climate and hydrogeology at the ice margin.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 199〈/p〉 〈p〉Author(s): Gifford H. Miller, John W. Magee, Marilyn L. Fogel, Matthew J. Wooller, Paul P. Hesse, Nigel A. Spooner, Beverly J. Johnson, Lynley Wallis〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A bolide that impacted NW Australia during the Late Quaternary left a circular depression more than 100 m deep and nearly a kilometer in diameter, with a crater rim ∼30 m above the regional terrain. The resultant crater is a window into the regional water table. The surface of the contemporary central pan is 25 m below the adjacent terrain, coincident with the late Holocene regional water table modified by local evaporative processes. Shielded from aeolian deflation by the crater rim, the central depression has slowly filled with dust, sand, and chemical precipitates, estimated to be 20–100 m thick based on geophysical surveys, one of the few continuous depocenters in the Australian Arid Zone. The nature of the crater's sediment fill is controlled by interactions between the water table, primarily in response to changes in summer monsoon rain, changes in the delivery of sand and dust to the crater by the prevailing easterly winds, and the level of the sedimentary fill surface. Optically Stimulated Luminescence (OSL) and 〈sup〉14〈/sup〉C dates constrain an age model indicating the upper 10 m of sediment fill recovered from the central pan span the past ∼60 ka. The lowest 3 m consist of clayey sand deposited in perennial water during Marine Isotope Stage (MIS) 3. The water table subsequently dropped rapidly ∼35 ka and remained more than 7 m below the late Holocene level through most of MIS 2, during which 2 m of sandy clay was deposited on a dry crater floor, confirming a dry and dusty Last Glacial Maximum (LGM) climate. By 14 ka a rising water table intersected the crater surface, modifying the upper 50 cm of LGM sediment, and syndepositionally modifying another 60 cm of subsequent sandy clay deposition. Aeolian sediment delivery effectively ceased ∼13 ka, and the upper 4.8 m is a gypsum-dominated precipitate, which initially accumulated rapidly, before equilibrating with the late Holocene water table shortly after 6 ka. Lacustrine carbonate encrustations on rocks at the base of the crater wall and ∼4 m above the central pan with 〈sup〉14〈/sup〉C ages 〉40 ka document a time when regional groundwater maintained a water body in the crater 3.5–4.5 m above the modern groundwater level. The crater wall deflected the prevailing easterly winds, creating a horseshoe-dune extending westerly on both sides of the crater, with an extension rate of 35 m ka〈sup〉−1〈/sup〉. An augered hole through the northern dune revealed 10 m of sediment overlying ferricrete. The lowest meter is a mixture of broken ferricrete and sand that we interpret to be debris from the bolide impact. Three OSL dates through the dune project an age for the debris-dune contact of 120 ± 10 ka. Changes in physical properties and bulk sediment δ〈sup〉13〈/sup〉C through the 9 m of aeolian sediment indicate the lowest 1.8 m was deposited during MIS 5 (120–85 ka), under a uniformly wetter climate than present. The overlying 4.3 m of sediment was deposited between 85 and 14 ka (MIS 4, 3, 2) and exhibits transitional characteristics between the lower unit and the upper 3.8 of sand, which was deposited primarily during the Holocene. Large changes in the regional water table occurred over the past 60 ka, including an LGM water table persistently ≥7 m lower than late Holocene levels, and 3.5–4.5 m higher prior to 40 ka, plausibly in MIS 5, indicative of a stronger Australian Summer Monsoon than at any time subsequently. Age models and sediment properties from the two sedimentary records indicate the crater was formed 〉60 ka and most likely ∼120 ka, more recently than previous estimates.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 13 June 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Charlie S. Bristow, Jonathan A. Holmes, Dave Mattey, Ulrich Salzmann, Hilary J. Sloane〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉During the African Humid Period (AHP) there was a large increase in the area of lakes and wetlands. Lake Megachad, one of several huge lakes, underwent dramatic fluctuations during the AHP prior to regression in the mid Holocene. However, the timing and nature of AHP termination has been disputed. We present evidence from sediments of the Angamma Delta, from the northern end of the palaeolake, for Lake Megachad lake-level fluctuations at the end of the AHP. Delta slope deposits were deposited around 7000 cal BP at the height of the AHP. Overlying bioclastic sediments, from 4300 to 4800 cal BP at an elevation of 285–290 m, lie below the palaeolake highstand (339 m) but close to the elevation of the Bahr el Ghazal sill, which divided the lake's two sub-basins. Ostracod δ〈sup〉18〈/sup〉O values indicate that the waters of the northern sub-basin were evaporated to levels similar to modern Lake Chad. Palaeoecological evidence suggests that the lake was perennial and evaporative enrichment is attributed to restricted circulation of lake waters as the sill emerged. The age and elevation of the bioclastic sediment, coupled with published lake level reconstructions, suggest a complex lake-level history with a major regression at the end of the AHP, followed by a short lived, lake level rise and then a further regression. This new evidence for changes in lake level provides support for other geological records and some modelling experiments that suggest rapid fluctuations in hydroclimate at the end of the AHP.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 200〈/p〉 〈p〉Author(s): Alexandra Skrivanek, Jin Li, Andrea Dutton〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Despite an abundance of U〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Th age data for Last Interglacial fossil corals in the Bahamas, the accuracy and precision of corresponding elevation data are poor, casting uncertainty on existing estimates of peak relative sea level and rates of sea-level change inferred from these deposits. We revisited two key sites at Great Inagua (GI) and San Salvador (SS) Island to test existing hypotheses about (1) the rate of sea level changes during the Last Interglacial period and (2) a possible gradient in peak sea level between these sites. Here, we provide precise elevation survey results for discrete stratigraphic horizons preserved at both locations, where two stages of reef growth are separated by a discontinuity that truncates corals in the lower reef. The discontinuity at Great Inagua manifests as a sharp wave-cut bench, with a maximum elevation of +1.14 m above mean sea level (MSL), that is sub-horizontal on the promontories and gradually slopes seaward in the embayments. At San Salvador, we observed a discontinuity that undulates between +0.85 and + 1.52 m. The uppermost surface of corals in growth position was measured at +1.94 m (GI) and +2.76 m (SS), although 〈em〉in situ〈/em〉 collapse and truncation of large 〈em〉Acropora palmata〈/em〉 colonies at the latter site implies that primary coral elevations were somewhat higher. Ultimately, assumptions regarding the amount of material truncated and paleowater depth of the observed reef facies at both sites dominate the uncertainty in calculating past sea level position and hence rates of sea-level change. Full consideration of errors associated with age and elevation data implies an ephemeral sea level drop of at least 1 m over a time frame of approximately one thousand years between two peaks in sea level.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 199〈/p〉 〈p〉Author(s): Michael E. Weber, Brendan T. Reilly〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The Bengal Fan contains the most complete record of Himalayan climate and tectonics. As the largest fan system of the world it is fed by the Ganges-Brahmaputra river systems. International Ocean Discovery Program (IODP) Expedition 354 cored seven sites along an east-west core transect at 8°N in the lower Bengal Fan. We studied the Pleistocene sections of these sites to provide constraints on the depositional history of the last 1.25 Ma. Low-resolution bio- and magnetostratigraphic constraints identified two regionally-extensive hemipelagic units and intercalated turbidite deposits that provide a chronostratigraphic framework for the 320 km transect. Using a combination of lithostratigraphy and sediment physical properties that vary on orbital timescales, we tuned high-resolution data sets to the LR04 benthic δ〈sup〉18〈/sup〉O isotope stack to obtain new constraints on the timing of depositional changes.〈/p〉 〈p〉Above the underlying Unit 1, which consists of Early to Middle Pleistocene turbiditic deposits, we divide four more units for the last 1.25 Ma: Unit 2, a Middle Pleistocene hemipelagic layer deposited at all sites from Marine Isotopic Stages (MIS) 37 to ∼17 (∼1.24–0.68 Ma) during the entire time of the Mid-Pleistocene Transition, when the Bengal Fan depocenter must have been distal to our transect; Unit 3, mostly turbidites with some intercalated hemipelgic sediments deposited from ∼MIS 16–∼13 (∼0.68–0.48 Ma), with sandy lithologies only found at the easternmost site on the west flank of the Ninetyeast Ridge; Unit 4, massive turbiditic sediments that started to dominate deposition with the Mid-Brunhes Transition (∼MIS 12) until MIS 7/8 (∼0.48–0.25 Ma), when the channel-levee system was focused east of the 85°E basement ridge at 8°N; and Unit 5, a Late Pleistocene hemipelagic layer at the top that spans MIS 7/8–1 (∼0.25 Ma to present) while the turbidite deposition was focused west of the 85°E basement ridge at 8°N. We find evidence that, on these timescales, deposition across the lower Bengal Fan changed with the evolution of Pleistocene climate, monsoon and sea-level history and hence responded to external controls on sediment accumulation and fan architecture rather than only fan-internal, autocyclic mechanisms.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 200〈/p〉 〈p〉Author(s): José Luis Guil-Guerrero〈/p〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 200〈/p〉 〈p〉Author(s): B.J. Davies, V.R. Thorndycraft, D. Fabel, J.R.V. Martin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We present 14 new 〈sup〉10〈/sup〉Be cosmogenic nuclide exposure ages quantifying asynchronous readvances during the Antarctic Cold Reversal from glaciers in the Baker Valley region of central Patagonia. We constrain glacier and ice-dammed palaeolake dynamics using a landsystems approach, concentrating on outlet glaciers from the eastern Northern Patagonian Icefield (NPI) and Monte San Lorenzo (MSL). Soler Glacier (NPI) produced lateral moraines above Lago Bertrand from 15.1 ± 0.7 to 14.0 ± 0.6 ka, when it dammed the drainage of Lago General Carrera/Buenos Aires through Río Baker at a bedrock pinning point. At this time, Soler Glacier terminated into the 400 m “Deseado” level of the ice-dammed palaeolake. Later, Calluqueo Glacier (MSL) deposited subaerial and subaqueous moraines in the Salto Valley near Cochrane at 13.0 ± 0.6 ka. These moraines were deposited in an ice-dammed palaeolake unified through the Baker Valley (Lago Chalenko; 350 m asl). The Salto Valley glaciolacustrine landsystem includes subaqueous morainal banks, ice-scoured bedrock, glacial diamicton plastered onto valley sides, perched delta terraces, kame terraces, ice-contact fans, palaeoshorelines and subaerial push and lateral moraines. Boulders from the subaqueous Salto Moraine became exposed at 12.1 ± 0.6 years, indicating palaeolake drainage. These data show an asynchronous advance of outlet glaciers from the Northern Patagonian Icefield and Monte San Lorenzo during the Antarctic Cold Reversal. These advances occurred during a period of regional climatic cooling, but differential moraine extent and timing of advance was controlled by topography and calving processes.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0277379118305912-fx1.jpg" width="199" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 19 September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Penny Spikins, Andy Needham, Barry Wright, Calvin Dytham, Maurizio Gatta, Gail Hitchens〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Evidence of care for the ill and injured amongst Neanderthals, inferred through skeletal evidence for survival from severe illness and injury, is widely accepted. However, healthcare practices have been viewed primarily as an example of complex cultural behaviour, often discussed alongside symbolism or mortuary practices. Here we argue that care for the ill and injured is likely to have a long evolutionary history and to have been highly effective in improving health and reducing mortality risks. Healthcare provisioning can thus be understood alongside other collaborative ‘risk pooling’ strategies such as collaborative hunting, food sharing and collaborative parenting. For Neanderthals in particular the selective advantages of healthcare provisioning would have been elevated by a variety of ecological conditions which increased the risk of injury as well their particular behavioural adaptations which affected the benefits of promoting survival from injury and illness. We argue that healthcare provisioning was not only a more significant evolutionary adaptation than has previously been acknowledged, but moreover may also have been essential to Neanderthal occupation at the limits of the North Temperate Zone.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0277379118305389-fx1.jpg" width="320" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 200〈/p〉 〈p〉Author(s): Xiaodong Miao, Paul R. Hanson, Christopher J. Stohr, Hong Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Most uplands in Illinois are blanketed by late-Wisconsinan Peoria Loess, and the conventional wisdom is that little or no dust accumulation occurred during the Holocene (11.7 ka to present). In a recent effort to investigate if Illinois Holocene loess was deposited and preserved, we applied optically stimulated luminescence (OSL) dating to seven locations where loess is thick. These include four sites along the Mississippi River in westernmost Illinois, and three loess bluffs south of the Illinois River in central Illinois. Our results suggest that Holocene-aged loess is preserved along the Mississippi River in the state of Illinois; in contrast, no Holocene loess was found south of the Illinois River in the central portion of the state. In addition to its spatially limited distribution, Holocene loess thicknesses range only up to 1 m. Nevertheless, loess stratigraphy and OSL dating results provide the first Holocene loess reported east of the Missouri River. Our new finding also resolves the long-time archeological puzzle that a number of artifacts of several thousand years old were buried by upland loess along the Mississippi River.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 200〈/p〉 〈p〉Author(s): Giulia Furlanetto, Cesare Ravazzi, Roberta Pini, Francesca Vallè, Michele Brunetti, Roberto Comolli, Massimo Domenico Novellino, Lorena Garozzo, Valter Maggi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We reconstructed the vegetation and climate history during the last 10 ka in a high-elevation sedimentary record (Armentarga peat bog, 2345 m asl) on the southern flank of the European Alps through the study of paleoecological and sedimentary proxies. We included a specific elevational transect of modern Pollen Accumulation Rates for timberline-forming trees and shrubs (〈em〉Alnus viridis, Pinus sylvestris/mugo, Pinus cembra〈/em〉). Quantitative reconstructions of July temperature and annual precipitation were obtained by applying numerical transfer functions built on an extensive pollen-climate calibration set from the European Alps. Changes in elevational vegetation arrangement were primarily driven by phases of precipitation increase, and to a lesser extent by millennial-scale temperature changes already known from glacier, timberline, chironomids and speleothem records at Alpine scale. Changes in pollen-inferred annual precipitation occurred in three main steps. An early Holocene moderately humid phase is mirrored by the early spread of 〈em〉Alnus viridis〈/em〉 dwarf forests. Precipitation started to increase at 6.2 ka cal BP. A further, prominent step forward at the Middle to Late Holocene transition led to the high values of snowfall and runoff characterizing today's oceanic elevational climates of the outer Italian Alps. This change led to timberline depression and grassland expansion. Locally, human impact was weak at the Late Neolithic/Bronze Age transition. This event correlates with lake level oscillations in the northern Mediterranean borderlands, suggesting intensification of southern air masses conveyed by Tyrrhenian cyclones towards windward districts.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 199〈/p〉 〈p〉Author(s): Alisa V. Baranskaya, Nicole S. Khan, Fedor A. Romanenko, Keven Roy, W.R. Peltier, Benjamin P. Horton〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉We present the first quality-controlled relative sea-level (RSL) database for the Russian Arctic coast from the Barents Sea in the west to Laptev Sea in the east (29–152〈sup〉o〈/sup〉E and 63 to 81〈sup〉o〈/sup〉N). The database consists of 385 sea-level index points and 249 limiting dates and spans 24 ka to present. Sea-level indicators are derived from multiple proxies, including isolation basins, raised beaches, glacial erratics, marine terraces, laidas (salt marshes), and deltaic salt marshes. Here, we calculate the indicative meanings for all indicators and evaluated possible elevation errors. We have estimated the ages and uncertainties of index points and limiting dates using the most recent calibration datasets.〈/p〉 〈p〉In the western Russian Arctic (Barents and White Seas), RSL was driven by glacial isostatic adjustment (GIA) due to deglaciation of the Eurasian ice sheet complex. For example, within the Baltic crystalline shield, RSL fell rapidly from 80 to 100 m at 11–12 ka to 15–25 m at ∼4–5 ka. In the Arctic Islands of Franz-Joseph Land and Novaya Zemlya, RSL gradually fell from 25 to 35 m at 9 ka to 5–10 m at 3 ka. The Timan coast and the Kara Sea shelf are characterized by constant RSL rise due to proglacial forebulge collapse; Yamal and the Gydan Peninsula and Novaya Zemlya are all marked by a high LGM position of RSL, followed by a lowstand and consequent rise to a late Holocene highstand of several meters. Data from the Laptev Sea coasts and shelf and the New Siberian Islands demonstrate post-LGM RSL rise with a Holocene highstand of up to 5–10 m, with scatter caused by differential tectonic movements along a diffuse lithospheric plate boundary. The collected database allowed to estimate and discuss the reasons of both spatial and temporal variability of RSL histories in different parts of the Russian Arctic.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 200〈/p〉 〈p〉Author(s): Daniel Veres, Viorica Tecsa, Natalia Gerasimenko, Christian Zeeden, Ulrich Hambach, Alida Timar-Gabor〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Here we provide a robust luminescence chronology for Stayky (Ukraine), a reference profile in European Late Pleistocene loess stratigraphy, based on optically stimulated luminescence (OSL) dating on quartz (4–11 μm, 63–90 μm) and post infrared-infrared stimulated luminescence (pIR-IRSL)) on polymineral fine grains. For the Bug loess unit, the equivalent of Marine Isotope Stage (MIS 2), results are in agreement between methods, demonstrating that the suite of embryonic soils previously interpreted as reflecting climate variability similar to Greenland interstadials (GI) actually date to ∼29/27-15 ka, with most emplaced around or after 20 ka. This temporal span is further confirmed by age-depth modelling of available data. Apart from GI-2, no interstadial-type climate events are recorded in Greenland ice core data for that time interval. As short-term pedogenetic phases are also documented in records from central-western Europe, there is a need for more research into the European mid-latitude terrestrial environments response to MIS 2 hydroclimate variability.〈/p〉 〈p〉The dating of Vytachiv paleosol, previously debatably linked to various GI events within MIS 3 resulted in ages of ∼40 ± 4 ka and ∼53 ± 4 ka at the lower transition, and ∼26 ± 2 ka to ∼30 ± 2 ka in the overlying loess. These ages indicate that the truncated Vytachiv paleosol is either not continuous, or that it encompasses a broader age range within MIS 3 than previously considered. In both cases, data would not allow for an unambiguous linking of this paleosol with specific GI events as previously attempted.〈/p〉 〈p〉The pIR-IRSL〈sub〉290〈/sub〉 dating of the loams immediately underneath Pryluky unit in the range of ∼120 ka to ∼168 ka and of the Pryluky mollisol from ∼90 ka to 126 ka confirm the broad correspondence of this unit with MIS 5, although poor dose recovery results open the possibility for further testing on the degree these ages provide overestimated results. Quartz data severely underestimate the pIR-IRSL〈sub〉290〈/sub〉 ages for these samples. The application of pIR-IRSL〈sub〉290〈/sub〉 dating for the underlying Dnieper till previously linked to the Saalian glaciation resulted in natural signals at the level of laboratory saturation, yielding minimum ages of c. 700 ka. For the same sample, the natural SAR-OSL signals for 4–11 μm quartz were found significantly below laboratory saturation level, resulting in finite ages of ∼250–270 ka interpreted here as underestimates, while coarse quartz (63–90 μm) signals reached about 85% of the laboratory saturation level. These data suggest extreme caution must be taken when dating such old samples using quartz OSL. Results from our high-resolution luminescence dating raises important implications for the chronological representativeness of Stayky as a key loess site in Eastern Europe beyond MIS 2.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 199〈/p〉 〈p〉Author(s): Bruce L. Hardy, Marie-Hélène Moncel, Jackie Despriée, Gilles Courcimault, Pierre Voinchet〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Middle Pleistocene hominins occupied Europe as early as 700 ka. Data on subsistence and adaptation to environment remain limited due to the small number of sites, especially from 700 to 500 ka. Current consensus suggests that Middle Pleistocene populations periodically peopled and depopulated areas of Europe in response to climatic fluctuations. Most occupations are located in the South, while the North-West was only occupied during favorable climatic periods. During this time, significant behavioral changes occur, such as bifacial technology and more complex modes of flaking. Further north in France, in the Loire basin, the site of la Noira has well-developed bifacial tools at around 700 ka, The site is located along a river with abundant millstone slabs which were flaked on the site suggesting it may have served partially as a lithic workshop. We employ use-wear and residue analysis (optical light and scanning electron microscopy) of stone tools to reconstruct early Acheulean hominin behavior. While the lithics are composed largely of retouched and unretouched debitage, large cutting tools (bifaces and cleavers) are also present. We demonstrate that la Noira was not only a lithic workshop, but that a broad range of resources were being used by the hominins at the site, including wood, plants, mammals, and possibly birds and fish. Finally, we compare our results with contemporary sites and suggest that, in the early European Acheulean, Middle Pleistocene hominins had detailed local environmental knowledge, and were able to adapt to a wide range of environments, including cool, temperate, and Mediterranean.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 5 October 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Asfawossen Asrat, Andy Baker, Melanie J. Leng, John Hellstrom, Gregoire Mariethoz, Ian Boomer, Dorothy Yu, Catherine N. Jex, John Gunn〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Oxygen and carbon (δ〈sup〉18〈/sup〉Ο/δ〈sup〉13〈/sup〉C) isotope, growth rate and trace element data are reported for a U-Th dated, annually-laminated stalagmite, GM1 from Goda Mea Cave, Ethiopia. The stalagmite grew intermittently around the last interglacial. The proxy records are used to develop a conceptual growth model of the stalagmite and to assess its potential for revealing a climate signal in this climatically sensitive northeastern African region during an important period in the evolution of 〈em〉Homo sapiens〈/em〉 and dispersal of Anatomically Modern Humans out of Africa. Speleothem deposition is of short-duration occurring at ∼129 ka, ∼120 ka, in an undated growth phase, and at ∼108 ka; probably due to tectonic activity. δ〈sup〉18〈/sup〉Ο composition is very stable within growth phases (1σ variability 〈 0.76‰), as are Mg/Ca, Sr/Ca and Ba/Ca, all indicative of well-mixed source-waters. A shift to positive δ〈sup〉18〈/sup〉Ο values and increased variability in Mg/Ca, Sr/Ca and Ba/Ca prior to growth hiatuses is observed, indicating a loss of the well-mixed water source prior to growth cessation. Mean δ〈sup〉18〈/sup〉Ο composition (−3.82 to −7.77‰) is lower than published modern and Holocene stalagmites from the region. Geochemical data, statistical analyses, and a conceptual model of stalagmite growth, demonstrate that climatic conditions recorded by GM1 were wetter than the Holocene. The ∼129 ka growth phase particularly presents an annual record of the relative Intertropical Convergence Zone (ITCZ) position. The GM1 record, the oldest high-resolution continental climate record from Ethiopia so far published, presents evidence that any early human migrations which occurred during MIS 5 are likely to have occurred during a wet event in northeast Africa.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 26 September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): N.J. Anderson, M.J. Leng, C.L. Osburn, S.C. Fritz, A.C. Law, S. McGowan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Arctic organic carbon (OC) stores are substantial and have accumulated over millennia as a function of changes in climate and terrestrial vegetation. Arctic lakes are also important components of the regional C-cycle as they are sites of OC production and CO〈sub〉2〈/sub〉 emissions but also store large amounts of OC in their sediments. This sediment OC pool is a mixture derived from terrestrial and aquatic sources, and sediment cores can therefore provide a long-term record of the changing interactions between lakes and their catchments in terms of nutrient and C transfer. Sediment carbon isotope composition (δ〈sup〉13〈/sup〉C), C/N ratio and organic C accumulation rates (C AR) of 〈sup〉14〈/sup〉C-dated cores covering the last ∼10,000 years from six lakes close to Sisimiut (SW Greenland) are used to determine the extent to which OC dynamics reflect climate relative to lake or catchment characteristics. Sediment δ〈sup〉13〈/sup〉C ranges from −19 to −32‰ across all lakes, while C/N ratios are 〈8 to 〉20 (mean = 12), values that indicate a high proportion of the organic matter is from autochthonous production but with a variable terrestrial component. Temporal trends in δ〈sup〉13〈/sup〉C are variable among lakes, with neighbouring lakes showing contrasting profiles, indicative of site-specific OC processing. The response of an individual lake reflects its morphometry (which influences benthic primary production), the catchment:lake ratio, and catchment relief, lakes with steeper catchments sequester more carbon. The multi-site, landscape approach used here highlights the complex response of individual lakes to climate and catchment disturbance, but broad generalisations are possible. Regional Neoglacial cooling (from ∼5000 cal yr BP) influenced the lateral transfer of terrestrial OC to lakes, with three lakes showing clear increases in OC accumulation rate. The lakes likely switched from being autotrophic (i.e. net ecosystem production 〉 ecosystem respiration) in the early Holocene to being heterotrophic after 5000 cal yr BP as terrestrial OC transfer increased.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 28 September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Haidee R. Cadd, John Tibby, Cameron Barr, Jonathan Tyler, Lilian Unger, Melanie J. Leng, Jonathan C. Marshall, Glenn McGregor, Richard Lewis, Lee J. Arnold, Tara Lewis, Jeff Baldock〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Continuous records of terrestrial environmental and climatic variability that extend beyond the Last Glacial Maximum (LGM) in Australia are rare. Furthermore, where long records do exist, interpretations of climate and ecological change can be hampered by marked changes in sedimentary environment which, in turn, affect the taphonomy of palaeoecological remains. As a consequence, in order to determine how wetland systems responded to climatic and environmental changes, we first need to understand how their depositional environment changed through time. Here we document the development of freshwater Welsby Lagoon, south-east Queensland, from a 12.7 m sediment sequence with a basal age of ca. 130,000 years. We present a variety of proxies reflecting change within the wetland. Carbon and nitrogen concentrations and carbon and nitrogen isotope ratios are used to infer the source of organic matter. However, the nitrogen limited nature of the catchment soils and presence of the colonial algae 〈em〉Botryococcus〈/em〉 meant that organic material with C:N ≥ 20 is likely to be derived from autochthonous sources rather than terrestrial sources. A combination of photosynthetic pigments, plant macrofossils, aquatic pollen and sedimentary lignin was used to identify the sources of organic matter and the changing nature of this wetland. Since its formation, Welsby Lagoon has undergone a progressive change from an open-water, algae and cyanobacteria dominated, freshwater lacustrine system, to an aquatic macrophyte-dominated palustrine swamp after ca. 40 ka. It did not revert to lacustrine conditions during the Holocene, despite what is widely viewed as an increase in the regional moisture balance, most likely due to continual infilling of the wetland with sediment. With so few records of terrestrial change throughout MIS3 and MIS4, adequately understanding the development of sites like Welsby Lagoon is imperative to advancing our knowledge of this important environmental and cultural period in Australia's history, which encompasses events such as the extinction of megafauna and human colonisation of the continent.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 199〈/p〉 〈p〉Author(s): V. Margari, K. Roucoux, D. Magri, G. Manzi, P.C. Tzedakis〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Climatic and environmental changes of the Middle Pleistocene in Europe provide the context for an important phase in the evolution and dispersal of early hominins. Pollen records from terrestrial and marine sediment sequences reveal patterns not usually visible in palaeoenvironmental reconstructions from archaeological sites alone and show that hominin evolution took place against a background of marked environmental change as forests expanded and contracted in concert with global and regional climatic shifts. It is rare to find archaeological material in stratigraphically long and continuous palaeoenvironmental sequences, yet this is what is needed to enable particular phases of hominin evolution to be securely associated with climatic and environmental changes. At the well-known Middle Pleistocene archaeological site of Ceprano in Italy we have been able to produce a pollen record from the sedimentary unit directly below the stratum of the hominin remains. The new pollen data from Ceprano are presented here in full for the first time and provide a detailed picture of interglacial vegetation development during Marine Isotope Stage (MIS) 13. This evidence contributes significantly to our knowledge of the spatial heterogeneity of ecosystem responses to climatic change during this period and helps to further constrain the age of the hominin remains. New sites combining both archaeology and long, continuous high quality palaeoecological records would help clarify the relationship between hominin presence and palaeoclimatic and palaeoenvironmental conditions. In the meantime, better communication between the research communities can also go a long way to improving our understanding of the links between the two.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 199〈/p〉 〈p〉Author(s): Alexander R. Simms, Pippa L. Whitehouse, Lauren M. Simkins, Grace Nield, Regina DeWitt, Michael J. Bentley〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Many studies of Holocene relative sea-level (RSL) changes across Antarctica assume that their reconstructions record uplift from glacial isostatic adjustment caused by the demise of the Last Glacial Maximum (LGM) ice sheets. However, recent analysis of GPS observations suggests that mantle viscosity beneath the Antarctic Peninsula is weaker than previously thought, which would imply that solid Earth motion is not controlled by post-LGM ice-sheet retreat but instead by late Holocene ice-mass changes. If this hypothesis is correct, one might expect to find Holocene RSL records that do not reflect a monotonic decrease in the rate of RSL fall but show variations in the rate of RSL change through the Holocene. We present a new record of late Holocene RSL change from Torgersen Island near Palmer Station in the western Antarctic Peninsula that shows an increase in the rate of relative sea-level fall from 3.0 ± 1.2 mm/yr to 5.1 ± 1.8 mm/yr during the late Holocene. Independent studies of the glacial history of the region provide evidence of ice-sheet changes over similar time scales that may be driving this change. When our RSL records are corrected for sea-surface height changes associated with glacial isostatic adjustment (GIA), the rate of post-0.79 ka land uplift at Torgersen Island, 5.3 ± 1.8 mm/yr, is much higher than the rate of uplift recorded at a nearby GPS site at Palmer Station prior to the Larsen B breakup in 2002 AD (1998-2002 AD; 〈0.1 mm/yr), but similar to the rates observed after 2002 AD (2002-2013 AD; 6–9 mm/yr). This substantial variation in uplift rates further supports the hypothesis that Holocene RSL rates of change are recording responses to late Holocene and recent changes in local ice loading rather than a post-LGM signal across portions of the Antarctic Peninsula. Thus middle-to-late Holocene RSL data may not be an effective tool for constraining the size of the LGM ice sheet across portions of the Antarctic Peninsula underlain by weaker mantle. In addition, current global-scale GIA models are unable to predict our observed changes in late Holocene RSL. Complexities in Earth structure and neoglacial history need to be taken into consideration in GIA models used for correcting modern satellite-based observations of ice-mass loss.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 17 July 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Vincenzo Spagnolo, Giulia Marciani, Daniele Aureli, Francesco Berna, Ginevra Toniello, Fernando Astudillo, Francesco Boschin, Paolo Boscato, Annamaria Ronchitelli〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Stratigraphic Unit 13 of Oscurusciuto Rockshelter (Ginosa, Taranto, Southern Italy) is a short Mousterian palimpsest representing the first stable occupation of the site soon after the deposition of a thick layer of tephra (Mt. Epomeo Green Tuff - Ischia datable around 55 kya BP).〈/p〉 〈p〉Different activities were identified by integrating the study of lithic finds, faunal remains, and the microarchaeology of combustion features. Additionally, geo-statistical analysis of these data has been carried out using a specifically designed geodatabase within a GIS platform.〈/p〉 〈p〉Our results produced an articulated picture of this Neanderthal site as a tripartite location made of spatially segregated and integrated activity areas. A hearths' alignment (parallel to the rockshelter wall) divides the settled area into an inner and outer part. The inner part, between the hearths and the shelter wall, displays an abrupt rarefaction of the anthropic finds and was interpreted as a possible sleeping/resting area. In the outer part, several multipurpose activity areas have been identified, mostly associated with the combustion features. The Northern sector of the settlement appears devoted particularly to lithic production (to a lesser degree, activities related with lithic tools use and faunal processing took place). In the Southern sector the main activities carried out represent more intensive production and use of lithic tools and the butchering and consumption of animal resources. Additionally, in this sector evidence of space maintenance behaviour (cleaning up of working areas and refuse dumping) has been attested.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 199〈/p〉 〈p〉Author(s): Thomas M. Urban, David Bustos, Jackson Jakeway, Sturt W. Manning, Matthew R. Bennett〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Tracks and trackways of a range of Pleistocene megafauna can be found in White Sands National Monument, New Mexico, U.S.A. These tracks occur is several forms, not all of which are visible and some of which are only intermittently visible depending on lighting and moisture conditions. Here we present the result of a successful test of cesium vapor magnetometry to detect a known Columbian mammoth trackway. This initial test found that not only the known mammoth tracks were easily detected by the method, but that the tracks of additional species, though not visible to the eye, were detected in the vicinity of the mammoth tracks, including likely giant sloth tracks. Our initial results indicate that resolution may be suitable to distinguish between the tracks of various species, including possibly humans which are known archaeologically to have overlapped temporally with these species in the southwestern U.S. This preliminary result has immediate implications for the detection and documentation of Pleistocene track sites, and further refinement of the procedure is planned in the coming months.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 199〈/p〉 〈p〉Author(s): Seigo Ooki, Tasuku Akagi, Hirooki Jinno, Lars G. Franzén, Jason Newton〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The 〈sup〉3〈/sup〉H concentration and stable isotope ratio of hydrogen and oxygen, δ〈sup〉2〈/sup〉H and δ〈sup〉18〈/sup〉O, of waters extracted from a 〈em〉Sphagnum〈/em〉-dominant raised bog in Lyngmossen, Sweden, were measured in order to understand where the precipitation is retained and how mobile it is. Three types of waters, which were defined by extractability, were collected from the peat. Two waters were extracted by compressing samples with different pressures (SQW1 and SQW2). The other water was obtained by distilling the compressed samples (DW). 〈sup〉3〈/sup〉H was detected in all types of water from depths of 0–50 cm: the concentrations in SQW1, SQW2 and DW ranged 1.17–3.07 Bq/L, 0.98–2.03 Bq/L, and 1.02–1.54 Bq/L, respectively. The maximum 〈sup〉3〈/sup〉H concentrations of SQW1, SQW2 and DW were all detected at a depth of around 15 cm, whose 〈sup〉14〈/sup〉C age covers the year of the atomic bomb experiments. The 〈sup〉3〈/sup〉H results of SQW1/2 indicate that SQW consists of at least two waters of different mobility, water flowing rapidly downward and immobile water. 〈em〉Sphagnum〈/em〉 hyaline cells may be responsible for the immobile water.〈/p〉 〈p〉The δ〈sup〉18〈/sup〉O and δ〈sup〉2〈/sup〉H relationship exhibited independent trends between SQW and DW. The distinct difference observed between the two waters at the surface (0–5 cm) indicates that the two waters may be supplied by precipitation at different times of the year, or alternatively that DW comprises plant water taken in from hyaline cells. The δ〈sup〉18〈/sup〉O and δ〈sup〉2〈/sup〉H values of both SQW and DW in the shallow layer increased with increasing depth, and in the layer around 30 cm depth, those of SQW showed a distinct decrease with depth. Isotope fractionation caused by evaporation and/or plant utilization of water at the surface layer are considered to be the main causes of such isotopic variation at the surface. Evaporation is likely to take place in much drier conditions for DW than for SQW, probably through stems by capillary action. In SQW freezing may be a possible cause for the decrease of δ〈sup〉18〈/sup〉O and δ〈sup〉2〈/sup〉H around 30 cm depth. DW is isotopically very well separated from two SQW1/2.〈/p〉 〈p〉Integrating all isotopic information, we conclude the presence of three different waters: least mobile water at shallow depth perhaps in hyaline cells, which can be extracted by squeezing peat with low pressure; most mobile water in a deeper layer than 30 cm, extracted also by squeezing peat; mobile but least extractable water, which is likely water inside plant tissues.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 200〈/p〉 〈p〉Author(s): Paul P. Hesse, Rory Williams, Timothy J. Ralph, Kirstie A. Fryirs, Zacchary T. Larkin, Kira E. Westaway, Will Farebrother〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study derives a new function describing the relationship of channel bankfull discharge (Q〈sub〉bf〈/sub〉) to channel width in modern rivers of the Murray-Darling Basin (MDB) of southeastern Australia and applies this to dated palaeochannels of seven rivers to quantify late Quaternary discharge history in this important basin. All rivers show high MIS3 and MIS2 Q〈sub〉bf〈/sub〉, declining in the Holocene. The Q〈sub〉bf〈/sub〉 of modern MDB rivers is correlated with total catchment precipitation but comparison with palaeochannel Q〈sub〉bf〈/sub〉 estimates shows that while enhanced runoff efficiency is necessary to account for much larger late Pleistocene palaeochannels, either lower or higher precipitation rates could have prevailed. A strong association between relative palaeo- Q〈sub〉bf〈/sub〉 enhancement and temperature suggests a temperature-mediated mechanism controlling river discharge, such as the fraction of precipitation stored as snow and thawing in spring, the enhancement of orographic rainfall, or CO〈sub〉2〈/sub〉 feedbacks with vegetation cover. Significantly enhanced MIS3 Q〈sub〉bf〈/sub〉 requires an additional mechanism, such as increased rainfall. These findings are consistent with others that increased moisture availability was associated with past colder climates, although this was not necessarily the result of enhanced precipitation.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 200〈/p〉 〈p〉Author(s): Vincent Rinterknecht, Tiit Hang, Aleksandr Gorlach, Marko Kohv, Katrin Kalla, Volli Kalm, Dmitry Subetto, Didier Bourlès, Laëtitia Léanni, Valéry Guillou, ASTER Team〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Recent synoptic studies have summarized the former spatial extent and chronology of the last Scandinavian Ice Sheet (SIS) and provide exceptional compilations of empirical datasets. The latter represent the primary source of information for the modelling community to test and develop thermomechanical ice sheet model, which are then further embedded into climatic and general circulation models. The Last Glacial Maximum (LGM) extent and chronology of the SIS across continental Europe were highlighted as being the least well-known thus generating the biggest uncertainties in the reconstruction of the ice sheet. While early geomorphological studies of the ice sheet marginal belts are numerous and detailed in western Russia, geochronological data are virtually inexistent. In an attempt to fill in this gap, we conducted a series of sampling campaigns for surface exposure dating using 〈sup〉10〈/sup〉Be in the western and northwestern regions of Russia. We present here the first results from the Valday Heights where glacial deposits constitute well-preserved margins of the SIS. A total of 16 samples firmly establish the timing of the LGM in the Valday Heights at 20.1 ± 0.4 ka. The Valday Heights acted as a natural wall for the last maximum advance of the SIS during MIS2, constraining the eastern flank of the Ladoga-Ilmen-Lovat ice stream to the west of the hills. The Valday Heights were only overran by previously more extensive glacial advances as suggested by older exposure ages obtain on erratic boulders (31.2 ± 1.4 to 47.1 ± 1.5 ka) located east of the LGM limit.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 200〈/p〉 〈p〉Author(s): Lei Zhang, Jiaqi Liu, Xiaoguang Qin, Yan Mu, Chunsheng Jin, Chunqing Sun, Jianxing Liu, Chenglong Deng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The thick late Cenozoic deposits of Huaibei Plain provide a record of paleoenvironmental changes in the northern and southern transitional zone of eastern China, and of the evolution of the Asian monsoon system. A detailed magnetostratigraphic study of the Huainan (HN, 481.45-m deep) drill core from the center of Huaibei Plain reveals a magnetic polarity sequence from chron C4n.2n to chron C1n, spanning the interval from ∼8 Ma to the present; it is the first reliable magnetostratigraphic chronology for the late Miocene to present for Huaibei Plain. The stratigraphic sequence contains three intervals characterized by major peaks in magnetic susceptibility (at depths of 58.8 m, 108.0 m and 312.4 m), which can be used as isochronous marker beds for regional stratigraphic correlations in Huaibei Plain. Major changes in sediment grain-size occur at 7.0 and 1.7 Ma, corresponding to pronounced environmental shifts, which we consider reflect the respective strengthening of the South Asian summer monsoon and East Asian winter monsoon at these times.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 200〈/p〉 〈p〉Author(s): Karin L. Zwiep, Rick Hennekam, Timme H. Donders, Niels A.G.M. van Helmond, Gert J. de Lange, Francesca Sangiorgi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Eastern Mediterranean sapropels S1 (∼10.5–6.1 kyr BP) and S3 (∼85.8–80.8 kyr BP) formed respectively under full interglacial and glacial inception conditions. Consequently, the environmental factors preconditioning and leading to sapropel formation (e.g., global sea level and monsoonal forcing) were different. These factors must have differently influenced processes such as marine productivity, water column processes, and related seafloor anoxia. Here we investigate these differences through an interdisciplinary approach using dinoflagellate cyst and pollen/spore assemblages and sedimentary (redox-sensitive) trace-metal concentrations from a core in the central Nile delta area. Comparing S1 to S3, we demonstrate that (1) Nile discharge appears to be stronger during S3 than S1, as shown by δ〈sup〉18〈/sup〉O〈sub〉residuals,〈/sub〉 higher ratio of pollen and spores, and the higher abundance of coastal dinocysts and freshwater palynomorphs, (2) Ba/Al, C〈sub〉org〈/sub〉, and dinocyst accumulation rates indicate that marine productivity was similar at least during the first phase of their deposition and started prior to the onset of both sapropels, (3) bottom water conditions were more reducing during S3, resulting in higher Mo/Al, S, and C〈sub〉org〈/sub〉/P〈sub〉tot〈/sub〉 values, but preservation was high and similar for both sapropels, and (4) Sedimentary Mo-〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉U covariation indicates that the depth of water-column ventilation during deposition of S3 was shallower than during S1 (∼1000 m versus ∼1800m, respectively). We attribute the observed differences to slightly enhanced precessional-forced monsoon intensity and potentially lower global sea level, resulting not only in increased North-African run-off, but also in reduced ventilation during S3 compared to S1.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 12 April 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): José María Bermúdez de Castro, María Martinón-Torres, Marina Martínez de Pinillos, Cecilia García-Campos, Mario Modesto-Mata, Laura Martín-Francés, Juan Luis Arsuaga〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The variability observed in the growing Middle Pleistocene hominin fossil record of Europe continues to trigger much debate on taxonomic issues and the biological processes that gave rise to Neanderthals. Here we present a metric and morphological comparative study of the dental samples recovered from the sites of Arago (southeast France) and Sima de los Huesos (SH) in the Sierra de Atapuerca (northern Spain). These sites are key to providing answers to these questions since they have yielded the largest hominin samples so far recovered for this time period. Despite the geographical proximity of the two sites and the contemporaneity of their hominin assemblages, we have observed remarkable metric and morphological differences between the teeth at Arago and SH. Whereas the SH teeth present an almost morphological identity with European Neanderthals, the Arago teeth exhibit a combination of plesiomorphic as well as some Neanderthal-derived features. In addition, the Arago crown dimensions are remarkably larger than those from SH, the differences being statistically significant for most variables. We hypothesize that during the Middle Pleistocene the European continent was settled at different points in time by hominin groups coming from Southwest Asia, probably from a common mother population evolving in this latter region. These first settlers can be identified by their more plesiomorphic morphology, whereas the most recent settlers are closer in appearance to Neanderthals. In addition, genetic processes such as isolation, genetic drift, directional adaptation or hybridization would have given rise to the puzzle we observe in the current fossil record.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 29 September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): P. Larcombe, I.A.K. Ward〈/p〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 200〈/p〉 〈p〉Author(s): S.J. Gallagher, L. Reuning, T. Himmler, J. Henderiks, D. De Vleeschouwer, J. Groeneveld, A. Rastegar Lari, C.S. Fulthorpe, K. Bogus, W. Renema, H.V. McGregor, M.A. Kominz, G. Auer, S. Baranwal, S. Castañeda, B.A. Christensen, D.R. Franco, M. Gurnis, C. Haller, Y. He〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Marine ooids are iconic indicators of shallow seawater carbonate saturation state, and their formation has traditionally been ascribed to physicochemical processes. The Indo-Pacific stands out as a region devoid of oolites, particularly during the Quaternary: the “ooid enigma”. Here we present results from recent coring by the International Ocean Discovery Program (IODP Expedition 356) off west Australia that shows that ooid horizons are common in Pleistocene strata up to 730,000 years old. Extensive “ooid factories” were created due to the presence of long-lived tidally influenced flat–topped tropical platforms suitable for intermittent ooid accretion over hundreds to thousands of years during highstands and times of lower sea level. This work suggests marine ooids may actually be more common in Indo-Pacific than previously reported. Past global ocean alkalinity was elevated during Pleistocene glacial periods and continental climate was generally more arid in the Indo-Pacific region compared to interglacials and the Holocene. Therefore, increased aridity associated with higher alkalinity conditions during the glacials facilitated ooid precipitation on adjacent tropical carbonate platforms particularly offshore from arid Australia. This confluence of factors suggests that more “ooid factories” may be encountered by further coring Indo-Pacific regions with Pleistocene flat long-lived carbonate shelves. However, Indo-Pacific Quaternary ooid occurrences outside Australia are rare, suggesting that the Northwest Shelf may be a unique archive of this non-skeletal precipitate. Further investigations into the petrography and geochemistry of pre-Holocene ooid occurrences will provide insights into their origin and the relative role of biotic, physicochemical and other factors in their formation.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 199〈/p〉 〈p〉Author(s): Qigao Jiangzuo, Jan Wagner, Jin Chen, Cuiping Dong, Jianhua Wei, Juan Ning, Jinyi Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉For a long time, it is controversial whether cave bears have ever lived in China during the Pleistocene. Here we checked the published and unpublished bear fossils from Zhoukoudian (North China) housed in Institute of Vertebrate Paleontology and Palaeoanthropology, CAS and Zhoukoudian Site Museum, and compared them with contemporary cave bears and brown bears. Our observation confirms the existence of cave bears only in Loc. 1 of Zhoukoudian. The general morphology of cave bears in China is similar to that of the early Middle Pleistocene cave bears in Europe and this bear can be assigned to 〈em〉Ursus deningeri〈/em〉. The metacarpals of 〈em〉U. deningeri〈/em〉 from Loc. 1 of Zhoukoudian are much plumper than those of the approximately contemporary 〈em〉U. deningeri〈/em〉 from Hundsheim (Austria) and are similar to those of the Late Pleistocene 〈em〉U. spelaeus〈/em〉/〈em〉ingressus〈/em〉, presumably with a good digging ability. In contrast to Europe and Caucasus, cave bears from China are much less abundant than brown bears during the Middle Pleistocene.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 200〈/p〉 〈p〉Author(s): Joseph M. Licciardi, Kenneth L. Pierce〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The Greater Yellowstone Glacial System (GYGS) covered about 20,000 km〈sup〉2〈/sup〉 at its maximum Pleistocene extent. The initiation, culmination, and ultimate decay of the GYGS involved complex interactions between several coalescent ice masses flowing from glacial source areas adjoining and including the Yellowstone Plateau. Here, we present an updated review of the history and dynamics of the GYGS during the penultimate (Bull Lake) and last (Pinedale) glaciations, drawing upon an integration of glacial-geologic mapping with 〉130 cosmogenic 〈sup〉10〈/sup〉Be and 〈sup〉3〈/sup〉He exposure ages.〈/p〉 〈p〉Bull Lake glacial deposits in greater Yellowstone are dated to ca. 150–140 ka and correlate with marine isotope stage 6. The Bull Lake glaciation extended well beyond the Pinedale along the southern and western GYGS margins, but Pinedale glaciers overrode Bull Lake ice limits on the north and east sides. The northeastward shift of the center of ice mass from Bull Lake to Pinedale time may be explained by uplift on the leading edge of the Yellowstone hotspot and subsidence on the trailing margin.〈/p〉 〈p〉In early Pinedale time (∼22–18 ka), ice buildup culminated in the high terrain of the Beartooth Uplift and High Absaroka Range. Glaciers from these source regions flowed onto the northeastern margin of the Yellowstone Plateau and advanced to terminal moraines beyond Clarks Fork Canyon and in Jackson Hole. By middle Pinedale time (∼18–16 ka), the Yellowstone Plateau ice cap surface had risen above the equilibrium-line altitude, stimulating orographic glacial buildup nourished by storms funneled eastward through the Snake River Plain. The plateau ice cap eventually thickened to 〉1000 m and joined glaciers from the Beartooth Uplift and Gallatin Range to form the northern Yellowstone outlet glacier. Terrain east and downwind of the ice cap crest was placed in a precipitation shadow, resulting in glacial recession in these regions. During the late Pinedale (∼16–13 ka), the plateau ice cap prograded southwestward toward the direction of moisture supply, leading to advances along the southern and western margins of the GYGS. Northern sectors of the plateau ice cap were nearly stagnant at this time. The Yellowstone region experienced widespread deglaciation ca. 15–14 ka in response to warming climate. Unloading of the ∼1 km-thick plateau ice cap and consequent release of pressure on the magmatic system beneath Yellowstone was not accompanied by volcanism, indicating that the magma chamber was not primed to erupt via decompression during the last deglaciation.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 199〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: Available online 29 September 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Finn A. Viehberg, Janna Just, Jonathan R. Dean, Bernd Wagner, Sven Oliver Franz, Nicole Klasen, Thomas Kleinen, Patrick Ludwig, Asfawossen Asrat, Henry F. Lamb, Melanie J. Leng, Janet Rethemeyer, Antoni E. Milodowski, Martin Claussen, Frank Schäbitz〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Archaeological findings, numerical human dispersal models and genome analyses suggest several time windows in the past 200 kyr (thousands of years ago) when anatomically modern humans (AMH) dispersed out of Africa into the Levant and/or Arabia. From close to the key hominin site of Omo-Kibish, we provide near continuous proxy evidence for environmental changes in lake sediment cores from the Chew Bahir basin, south Ethiopia. The data show highly variable hydroclimate conditions from 116 to 66 kyr BP with rapid shifts from very wet to extreme aridity. The wet phases coincide with the timing of the North African Humid Periods during MIS5, as defined by Nile discharge records from the eastern Mediterranean. The subsequent record at Chew Bahir suggests stable regional hydrological setting between 58 and 32 kyr (MIS4 and 3), which facilitated the development of more habitable ecosystems, albeit in generally dry climatic conditions. This shift, from more to less variable hydroclimate, may help account for the timing of later dispersal events of AMH out of Africa.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 199〈/p〉 〈p〉Author(s): Willy Fjeldskaar, Stein Bondevik, Aleksey Amantov〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉About 60% of Svalbard is covered by glaciers today, but many of these glaciers were much reduced in size or gone in the Early Holocene. High resolution modeling of the glacial isostatic rebound reveals that the largest glaciers in Nordaustlandet and eastern Spitsbergen survived the Early Holocene warming, while the smaller, more peripheral glaciers, especially in the northwest, started to form about 5,500 years ago, and reached 3/4 of their current size about 600 years ago. Relative sea level has been rising during the last few millennia in the north and western parts of Spitsbergen, while land still emerges in the remaining part of Svalbard. Here we show that this sea level rise in the northwest is caused by the regrowth of glaciers in the Mid- to Late Holocene that slowed down, and even reversed, the post-glacial isostatic uplift and caused the crust to subside over large areas of Spitsbergen.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 199〈/p〉 〈p〉Author(s): Yajuan Du, Weijian Zhou, Feng Xian, Xiaoke Qiang, Xianghui Kong, Guoqing Zhao, Xingjun Xie, Yunchong Fu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We present a new 〈sup〉10〈/sup〉Be record spanning the Matuyama-Brunhes (M-B) reversal from the Heqing paleolake basin in southern China. It provides a robust proxy for past geomagnetic variations that can be compared with paleomagnetic records. The M-B transition is identified as a pronounced maximum of authigenic 〈sup〉10〈/sup〉Be/〈sup〉9〈/sup〉Be ratio between 768.6 and 778.5 ka, that is consistent with all other available 〈sup〉10〈/sup〉Be-proxy records from marine, ice and loess archives. However, it is offset by approximately 0–60 cm depth from the magnetic signature of the polarity transition recorded in the same sediments. We attribute this offset to the lock-in effect of the remanence acquisition process, which is similar to the phenomenon that exists in marine sediments. We suggest that after eliminating the climatic-hydrological signal, the Heqing sediments may be used as an archive for atmospheric 〈sup〉10〈/sup〉Be production rate changes. The combination of magnetic remanence measurements and the cosmogenic 〈sup〉10〈/sup〉Be allows for a more precise geochronology of geomagnetic polarity reversals.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 199〈/p〉 〈p〉Author(s): Jiaju Zhao, Elizabeth K. Thomas, Yuan Yao, Jody DeAraujo, Yongsong Huang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉There have been numerous attempts to use long-chain alkenones (LCAs) in saline lakes for paleotemperature and paleosalinity reconstructions. However, LCAs in saline lakes are often produced by multiple haptophyte species, which may confound data interpretations. Here we analyzed LCAs in a finely laminated, high sedimentation rate core from the hypersaline Lake Gahai in the northern Qinghai-Tibetan Plateau and compared our results with regional instrumental records. We find that LCA unsaturation ratios display a stepwise jump during the instrumental period, most likely originating from a sudden shift in the dominant alkenone producers. In contrast, the percentage of the C〈sub〉37:4〈/sub〉 alkenone (%C〈sub〉37:4〈/sub〉) displays strong correlations with spring and combined winter-spring precipitation amount (R〈sup〉2〈/sup〉 = 0.83 and R〈sup〉2〈/sup〉 = 0.81, respectively). We hypothesize that high winter-spring precipitation leads to greater freshening of lake surface water immediately after spring melting, promoting greater production of LCAs with relatively high %C〈sub〉37:4〈/sub〉 values by the early blooming haptophyte species. Extending the instrumental calibration downcore allows us to quantitatively reconstruct regional spring and winter-spring precipitation for the past millennium. We find a major increase in winter-spring precipitation during the Little Ice Age (LIA), especially during the phases of solar minima. Our finding provides novel quantitative support to the previous studies suggesting relatively wet conditions during the LIA in the westerly dominated regions of central Asia and northern Tibetan Plateau and infers a substantial increase in regional winter-spring precipitation should the predicted grand solar minimum in the forthcoming decades become a reality.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 203〈/p〉 〈p〉Author(s): R.L. Barnett, P. Bernatchez, M. Garneau, M.J. Brain, D.J. Charman, D.B. Stephenson, S. Haley, N. Sanderson〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Late Holocene sea-level changes can be reconstructed from salt-marsh sediments with decimetre-scale precision and decadal-scale resolution. These records of relative sea-level changes comprise the net sea-level contributions from mechanisms that act across local, regional and global scales. Recent efforts help to constrain the relative significance of these mechanisms that include sediment dynamics and isostasy, which cause relative sea-level changes via vertical land motion, ocean-atmosphere processes that influence regional-scale ocean mass redistribution, and ocean-cryosphere and steric interactions that drive global scale ocean-volume changes. There remains a paucity of high-resolution Late Holocene sea-level data from eastern Canada. This precludes an interrogation of the mechanisms that define sea-level changes over recent centuries and millennia in a region sensitive to oceanic (Atlantic Multidecadal Variability, Atlantic Meridional Overturning Circulation), atmospheric (North Atlantic Oscillation, Arctic Oscillation) and cryospheric (ice-mass balance) changes. We present new relative sea-level data that span the past three millennia from Baie des Chaleurs in the Gulf of St. Lawrence generated using salt-marsh foraminifera supported with plant macrofossil analyses. The accompanying chronology is based on radiocarbon and radionuclide analyses, which are independently verified using trace metal and microcharcoal records. Relative sea level has risen at a mean rate of 0.93 ± 1.25 mm yr〈sup〉−1〈/sup〉 over the past ∼1500 years. Residual structure within the reconstruction (‘internal variability’) has contributed up to an additional 0.61 ± 0.46 mm yr〈sup〉−1〈/sup〉 of short-lived RSL rise prior to 1800 CE. Following a sea-level low stand during the Little Ice Age, acceleration in relative sea-level rise is identified between 1800 and 1900 CE within the estimates of internal variability and from 1950 CE to present in both the secular and residual trends. Phases of relative sea-level changes in the Gulf of St. Lawrence are concomitant with periods of glacier mass loss following the Little Ice Age, phase periods of the North Atlantic Oscillation and the Atlantic Meridional Overturning Circulation and Northern Hemisphere warming. Quantifying the individual effects of these different mechanisms is important for understanding how ocean-atmosphere processes redistribute ocean-mass upon larger scale background ocean-volume changes.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 201〈/p〉 〈p〉Author(s): V. Vanghi, A. Borsato, S. Frisia, R. Drysdale, J. Hellstrom, P. Bajo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A stalagmite (FR16) from Frasassi Cave, located near the Adriatic coast of the Italian peninsula, offers a 16 kyr petrographic and stable isotope record spanning from 112.8 ± 1.5 ka to 96.6 ± 1.0 ka, corresponding to the interval from marine isotope stage (MIS) 5c to MIS 5d. The physical characteristics of FR16 calcite, allowed for a thorough understanding of the processes controlling isotopic changes, because fabrics as well are controlled by the environmental parameters within the cave that reflect external climate forcing. The FR16 δ〈sup〉13〈/sup〉C profile matches fabric changes where columnar fabric usually corresponds to more negative values and micrite/microsparite layers to less negative δ〈sup〉13〈/sup〉C values, and with the North Greenland Ice-core Project (NGRIP) δ〈sup〉18〈/sup〉O record with more negative δ〈sup〉13〈/sup〉C values during interstadials GI24 and GI23. This suggests a hydrological sensitivity for the two proxies, and their variability can be linked to recharge changes. On the other hand, the response to Greenland events appears subdued in the δ〈sup〉18〈/sup〉O record and the trend mimics instead the Northern Hemisphere (NH) summer insolation with more negative δ〈sup〉18〈/sup〉O values corresponding to the maximum insolation centred at ca. 105 ka. This behaviour can be explained by the higher sensitivity of δ〈sup〉18〈/sup〉O to rainfall seasonality, moisture source and trajectories, whose combined effect attenuated the stadials/intersadials signal in the stalagmite.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 10 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Laura Sadori〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The top 12 m of a lacustrine sediment sequence from Lago di Mezzano (42°36′N, 11°46′E, 452 a.s.l., Latium, central Italy) have been palynologically investigated. The chronology was established on the basis of radiocarbon dates, measures of annual laminations and volcanic ashes. The continuous sequence provides new fundamental information on the Lateglacial and Holocene, periods often fragmented in Italian pollen records, identifying vegetation dynamics and climate changes occurring in the last 15,300 years. The record starts at the end of the last glacial, closely following the climate changes found at a global scale, with clear stadial and interstadial oscillations, and evidence of cold/dry and wet/warm climatic changes. The Holocene is mostly characterized by forests, evolving rapidly to mature mixed deciduous oak (starting from 11,000 years BP) and, passing through beech forests (starting from ca. 9000 years BP) and alder carrs (starting from ca. 7000 years) to the deeply human-modified present-day landscape.〈/p〉 〈p〉Evaluating the importance of the local and regional human impact is not straightforward. A peculiarity of Lago di Mezzano, as of other Mediterranean lacustrine sites, is that it behaves at times as an “on-site” locale, when human populations were immediately by the lake, and at times as an “off-site” when settlements were found further away. This pattern changed according to cultural and climatic variations, both correlated to the water level of the lake.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 203〈/p〉 〈p〉Author(s): Camille Li, Andreas Born〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Dansgaard-Oeschger events of the last ice age are among the best studied abrupt climate changes, yet a comprehensive explanation is still lacking. They are most pronounced in the North Atlantic, where they manifest as large temperature swings, on timescales of decades or shorter, between persistent cold (stadial) and warm (interstadial) conditions. This review examines evidence that Dansgaard-Oeschger events are an unforced or “spontaneous” oscillation of the coupled atmosphere-ice-ocean system comprising the North Atlantic, Nordic Seas and Arctic, collectively termed the Northern Seas. Insights from reanalysis data, climate model simulations, and idealized box model experiments point to the subpolar gyre as a key coupling region where vigorous wind systems encounter the southernmost extension of sea ice and the most variable currents of the North Atlantic, with connections to the deep ocean via convection. We argue that, under special conditions, these components can interact to produce Dansgaard-Oeschger events. Finding the sweet spot is a matter of understanding when the subpolar region enters a feedback loop whereby changes in wind forcing, sea ice cover, and ocean circulation amplify and sustain perturbations towards cold (ice-covered) or warm (ice-free) conditions. The resulting Dansgaard-Oeschger-like variability is seen in a handful of model simulations, including some “ugly duckling” pre-industrial simulations: these may be judged as undesirable at the outset, but ultimately show value in suggesting that current models include the necessary physics to produce abrupt climate transitions, but exhibit incorrect sensitivity to the boundary conditions. Still, glacial climates are hypothesized to favour larger, more persistent transitions due to differences in large-scale wind patterns. Simplified models and idealized experimental setups may provide a means to constrain how the critical processes act, both in isolation and in combination, to destabilize the subpolar North Atlantic.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 203〈/p〉 〈p〉Author(s): Stéphane Molliex, Albert J. Kettner, Dimitri Laurent, Laurence Droz, Tania Marsset, Alain Laraque, Marina Rabineau, Guy D. Moukandi N'Kaya〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The Congo River is the world's second largest river in terms of drainage area and water discharge. Monitored for decades, a large dataset is available, onshore for both the hydrology and sediment load, and offshore by many paleo-environmental proxies compiled at the Late-Quaternary time-scale. These numerous data allow for accurate calibration of numerical modeling. In this study, we aim to numerically quantify the evolution of sediment supply leaving the tropical Congo watershed during the last 155 ka and to decipher the forcing parameters that control this sediment supply over glacial/interglacial stages. For this, a modified version of the model HydroTrend, that besides morphologic, climatic, hydrologic, lithologic, land cover and anthropogenic factors now also considers sediment deposition on the floodplain, is used. In addition, a method to quantify the impact of natural vegetation changes is developed.〈/p〉 〈p〉Simulations match well the present-day observed data. They indicate that a significant portion of suspended sediments is trapped on the floodplain. Long-term simulations indicate that environmental changes between glacial and interglacial stages account for a 30% maximum variation of sediment supply. Climatic changes - precipitation and temperature, account for a maximum decrease in sediment supply of 20% during cold periods while conversely, induced land cover changes (loss of forest during colder and dryer stages) lead to enhanced sediment supply up to 30%. Over a longer period, the average sediment supply remained almost constant during glacial and interglacial periods, while peaks may have occurred during a warming period, just before forests had time to recover the catchment, i.e. during post-glacial periods. These moderate changes in sediment export, despite major changes in climate and vegetation cover, can be explained by the efficiency of sediment trapping of large tropical catchments that buffer fluvial fluxes towards the ocean.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 203〈/p〉 〈p〉Author(s): A.V. Lozhkin, P.M. Anderson, O. Yu Glushkova, L.N. Vazhenina〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Palynological and plant macrofossil data and remains of 〈em〉Mammuthus primigenius〈/em〉 from the Tanon quarry (59° 40′ N, 151° 12′ E) provide much needed information about environments in southwestern Beringia during the Middle Holocene and marine isotope stages (MIS) 2 and 3. During the Middle Holocene, 〈em〉Larix-Betula〈/em〉 forest characterized the Tanon region and differed from the 〈em〉Larix〈/em〉 forests of interior Western Beringia. 〈em〉Betula platyphylla〈/em〉, which today is more common in moderate regions of the Far East, was an important component of the coastal forest near the quarry and possibly was more extensive in the coastal lowland. Ecological and quantitative models suggest that the coastal region experienced longer growing seasons and warmer summer temperatures, which could support the expansion of tree 〈em〉Betula〈/em〉. The MIS 2 palynological assemblage from Tanon indicates a prevalence of mesic and xeric herb-dominated tundra. However, the macrofossil data consist largely of taxa found in forest or forest-tundra with only a minor contribution by steppe species. The Tanon results agree with the larger paleovegetation database from Beringia, which suggests that steppe was not widespread during the Late Pleistocene but rather the landscape was characterized by a mosaic of tundra types. The Tanon site provides the first information about MIS 3 coastal vegetation, indicating the presence of 〈em〉Larix-Betula〈/em〉 forest within valleys and shrub tundra at higher elevations. The discovery of 〈em〉Mammuthus primigenius〈/em〉 in the quarry marks the southernmost population of Late Pleistocene mammoths in Western Beringia.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 201〈/p〉 〈p〉Author(s): Matthew J. Amesbury, Robert K. Booth, Thomas P. Roland, Joan Bunbury, Michael J. Clifford, Dan J. Charman, Suzanne Elliot, Sarah Finkelstein, Michelle Garneau, Paul D.M. Hughes, Alexandre Lamarre, Julie Loisel, Helen Mackay, Gabriel Magnan, Erin R. Markel, Edward A.D. Mitchell, Richard J. Payne, Nicolas Pelletier, Helen Roe, Maura E. Sullivan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Fossil testate amoeba assemblages have been used to reconstruct peatland palaeohydrology for more than two decades. While transfer function training sets are typically of local-to regional-scale in extent, combining those data to cover broad ecohydrological gradients, from the regional-to continental- and hemispheric-scales, is useful to assess if ecological optima of species vary geographically and therefore may have also varied over time. Continental-scale transfer functions can also maximise modern analogue quality without losing reconstructive skill, providing the opportunity to contextualise understanding of purely statistical outputs with greater insight into the biogeography of organisms. Here, we compiled, at moderate taxonomic resolution, a dataset of nearly 2000 modern surface peatland testate amoeba samples from 137 peatlands throughout North America. We developed transfer functions using four model types, tested them statistically and applied them to independent palaeoenvironmental data. By subdividing the dataset into eco-regions, we examined biogeographical patterns of hydrological optima and species distribution across North America. We combined our new dataset with data from Europe to create a combined transfer function. The performance of our North-American transfer function was equivalent to published models and reconstructions were comparable to those developed using regional training sets. The new model can therefore be used as an effective tool to reconstruct peatland palaeohydrology throughout the North American continent. Some eco-regions exhibited lower taxonomic diversity and some key indicator taxa had restricted ranges. However, these patterns occurred against a background of general cosmopolitanism, at the moderate taxonomic resolution used. Likely biogeographical patterns at higher taxonomic resolution therefore do not affect transfer function performance. Output from the combined North American and European model suggested that any geographical limit of scale beyond which further compilation of peatland testate amoeba data would not be valid has not yet been reached, therefore advocating the potential for a Holarctic synthesis of peatland testate amoeba data. Extending data synthesis to the tropics and the Southern Hemisphere would be more challenging due to higher regional endemism in those areas.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 17 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Melanie J. Leng, Warren Eastwood, Matthew D. Jones〈/p〉

Description: 〈p〉Publication date: Available online 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Scott St. George, Jan Esper〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We review the current generation of large-scale, millennial-length temperature reconstructions derived from tree rings and highlight areas of agreement and disagreement among these state-of-the-art paleotemperature estimates. Although thousands of tree ring-width chronologies are now available from temperate and boreal forest sites across the Northern Hemisphere, only a small fraction of those records are suited as proxies for surface temperature. Maximum latewood density is clearly a superior temperature proxy but is less available, with few densitometric records that are both long and up-to-date. Compared to previous efforts, the newest generation of tree-ring reconstructions correlate more strongly against hemispheric summer temperatures and show better performance in tracking decadal/multi-decadal variability and year-to-year fluctuations. They also fit the observed memory structure of instrumental temperatures more closely than their predecessors. These new estimates still show signs of the so-called ‘divergence problem’ (the apparent loss of temperature sensitivity under recent warming), but do not extend after 2004 and cannot be used to evaluate the impact of the past decade's warming on northern temperature-limited forests. We caution against averaging together the latest hemispheric-scale reconstructions because they have each been constructed to suit different purposes and share much of the same underlying tree-ring data, especially prior to CE 1500. Past temperatures are recorded more clearly in maximum latewood density than total ring-width, so we recommend the Northern Hemisphere densitometry network be modernized through a new round of field collections and observations.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 17 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Helen M. Roberts, Charlotte L. Bryant, Dei G. Huws, Henry F. Lamb〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The lakes of the eastern Africa Rift often contain great thicknesses of sediment that may provide continuous records of environmental change over decadal to million-year timescales. However interpretation of these changes is greatly compromised without a reliable chronology. Luminescence dating has not been used extensively in lacustrine settings; instead previous studies have often relied upon radiocarbon dating, using extrapolation beyond the upper limit of that technique, and employing opportunistic sampling of tephra and palaeomagnetic signatures where possible. This study from Lake Tana, Ethiopia, demonstrates that recent advances in luminescence methodology can provide long chronologies for lake sediments that are not dependent on the intermittent presence of dateable material, as is the case for radiocarbon and tephra-based methods. Specifically, this study generates luminescence ages that agree with independent chronology based on radiocarbon dating in the upper part of the core, and extends significantly beyond the range of radiocarbon dating to provide one of the longest independently dated lacustrine sediment records in eastern Africa, thus demonstrating the tremendous potential of luminescence for constructing lacustrine sediment chronologies over 100,000 year timescales.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 15 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Keely Mills, Christopher H. Vane, Raquel A. Lopes dos Santos, Immaculate Ssemmanda, Melanie J. Leng, David B. Ryves〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The exploitation of lakes has led to large-scale contemporary impacts on freshwater systems, largely in response to catchment clearance. Such clearance is causing changes to carbon dynamics in tropical lakes which may have significance for wider carbon budgets, depending on the changes in carbon sequestration and mineralisation driven by changing roles of terrestrial and aquatic carbon in lakes over time. Despite increasing awareness of the pivotal role of carbon source in carbon dynamics, discriminating the source of carbon from a palaeolimnological record is rarely undertaken. Here we use novel geochemical techniques (brGDGTs, 〈em〉n〈/em〉-alkanes, Rock-Eval pyrolysis), paired with traditional analyses (diatoms, pollen), to elucidate changing sources of carbon through time and ecosystem response.〈/p〉 〈p〉Environmental changes at Lake Nyamogusingiri can be divided into three phases: Phase I (CE 1150–1275), a shallow and productive lake, where a diverse terrestrial environment is, initially, the main carbon source, before switching to an aquatic source; Phase II (CE 1275–1900), variable lake levels (generally in decline) with increasing productivity, and carbon is autochthonous in source; Phase III (CE 1900–2007), lake level declines, and the carbon is of a mixed source, though the terrestrially derived carbon is from a less diverse source.〈/p〉 〈p〉The organic geochemical analyses provide a wealth of data regarding the complexity of aquatic response to catchment and with-in lake changes. These data demonstrate that small, tropical lake systems have the potential to bury high quantities of carbon, which has implications for the disruption of local biogeochemical cycles (C, P, N, and Si) both in the past, and the future as human and climate pressures increase.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 16 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Matthew D. Jones, Sylvia G. Dee〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Proxy System Modelling (PSM) is now recognised as a crucial step in comparing climate model output with proxy records of past environmental change. PSMs filter the climate signal from the model, or from meteorological data, based on the physical, chemical and biological processes of the archive and proxy system under investigation. Here we use a PSM of lake carbonate δ〈sup〉18〈/sup〉O to forward model pseudoproxy time-series for every terrestrial grid square in the SPEEDY-IER isotope enabled General Circulation Model (GCM), and compare the results with 31 records of lake δ〈sup〉18〈/sup〉O data from the Americas in the NOAA Paleoclimate Database. The model-data comparison shows general patterns of spatial variability in the lake δ〈sup〉18〈/sup〉O data are replicated by the combination of SPEEDY-IER and the PSM, with differences largely explained by known biases in the models. The results suggest improved spatial resolution/coverage of climate models and proxy data, respectively, is required for improved data-model comparison, as are increased numbers of higher temporal resolution proxy time series (sub decadal or better) and longer GCM runs. We prove the concept of data-model comparison using isotope enabled GCMs and lake isotope PSMs and outline potential avenues for further work.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 17 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): J. Tibby, J.J. Tyler, C. Barr〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Understanding the relative influences of climate and people in driving environmental change is a fundamental aspect of Quaternary research. In Australia, numerous studies have investigated the effect of European settlement on the landscape, yet few have explicitly explored the role that natural climate variability played in modulating those impacts. Using a combination of new and existing proxy data, we demonstrate that European settlement of eastern Australia coincided with a marked decline in available moisture which occurred towards the end of the nineteenth century, 〈em〉c.〈/em〉 1850–1900 CE. This marked decline in rainfall would have increased ecosystem vulnerability to a number of human-induced stressors. By contrast, this aridification is likely to have masked some impacts of European occupation, in particular increased catchment runoff resulting from land clearance. We propose that the eastern Australian landscape has therefore suffered dual stressors of agricultural expansion and climate drying, with implications for both establishing environmental baselines and natural resource management.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 201〈/p〉 〈p〉Author(s): Qian Zhang, Chaolu Yi, Guocheng Dong, Ping Fu, Ninglian Wang, Domenico Capolongo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Gangdise Mountains are located in a transition zone between the Indian Summer Monsoon-dominated Himalaya Mountains and the Westerlies-dominated Qiangtang Plateau. The timing and extent of the paleoglaciations in the central Gangdise Mountains remain unclear. We investigated the glacial history of the southeastern slopes of Lopu Kangri using 〈sup〉10〈/sup〉Be exposure dating and summarized the dating results for the western and eastern sectors of the Gangdise Mountains. Glacial events were constrained to ≥243.88 ± 25.88 ka, ≥ 43.09 ± 4.18 ka, 24.19 ± 2.29 ka, 19.78 ± 1.9 ka, 10.62 ± 1 ka, 2.75 ± 0.37 ka, 1.8 ± 0.18 ka, 0.32 ± 0.04 ka and 0.22 ± 0.04 ka, representing paleoglaciations which occurred during marine isotope stage (MIS) 8/7 or earlier, MIS 3 or earlier, early MIS 2, the global Last Glacial Maximum (LGM), the early Holocene, the Neoglacial and the Little Ice Age (LIA). Evidence of MIS 5 or earlier glaciations, and the glaciations during MIS 3, early and late MIS 2, the global LGM and the LIA, can be found in the western or eastern sectors of the Gangdise Mountains. The spatial trend in ΔELA values in the Gangdise and surrounding mountain ranges would appear to have been controlled by particular precipitation distribution patterns. The glacial events identified in the Gangdise Mountains during MIS 2, the Neoglacial and the LIA appear consistent with previously-identified cold periods. Precipitation was most likely a contributory cause of the glaciations during the MIS 3, early Holocene, the Neoglacial and the LIA.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 201〈/p〉 〈p〉Author(s): Christopher Berndt, Cengiz Yıldırım, Attila Çiner, Manfred R. Strecker, Gülgün Ertunç, M. Akif Sarıkaya, Orkan Özcan, Tugba Ozturk, Nafiye Gunec Kiyak〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We analysed the interplay between coastal uplift, sea level change in the Black Sea, and incision of the Kızılırmak River in northern Turkey. These processes have created multiple co-genetic fluvial and marine terrace sequences that serve as excellent strain markers to assess the ongoing evolution of the Pontide orogenic wedge and the growth of the northern margin of the Central Anatolian Plateau. We used high-resolution topographic data, OSL ages, and published information on past sea levels to analyse the spatiotemporal evolution of these terraces; we derived a regional uplift model for the northward-advancing orogenic wedge that supports the notion of laterally variable uplift rates along the flanks of the Pontides. The best-fit uplift model defines a constant long-term uplift rate of 0.28 ± 0.07 m/ka for the last 545 ka. This model explains the evolution of the terrace sequence in light of active tectonic processes and superposed cycles of climate-controlled sea-level change. Our new data reveal regional uplift characteristics that are comparable to the inner sectors of the Central Pontides; accordingly, the rate of uplift diminishes with increasing distance from the main strand of the restraining bend of the North Anatolian Fault Zone (NAFZ). This spatial relationship between the regional impact of the restraining bend of the NAFZ and uplift of the Pontide wedge thus suggests a strong link between the activity of the NAFZ, deformation and uplift in the Pontide orogenic wedge, and the sustained lateral growth of the Central Anatolian Plateau flank.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 201〈/p〉 〈p〉Author(s): Hiroto Kajita, Hodaka Kawahata, Ke Wang, Hongbo Zheng, Shouye Yang, Naohiko Ohkouchi, Masayuki Utsunomiya, Bin Zhou, Bang Zheng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the estuary region of the Yangtze River (China), the oldest Neolithic civilization based on paddy rice cultivation flourished in the mid-Holocene (7.5–4.2 cal. kyr BP). However, although it is known that this Neolithic civilization collapsed at around 4.2 cal. kyr BP, the reason behind the collapse remains controversial. A sedimentary core (MD06-3040) collected from the inner shelf of the East China Sea, off the southeast coast of China, provides an excellent insight into estimate the Holocene regional paleoenvironment, including the alkenone based sea surface temperature (SST), atmospheric temperature (AT), and paleoproductivity. Extraordinarily severe abrupt cold episodes (i.e., 3–4 °C drop in SST) occurred frequently in the Yangtze delta region during 4.4–3.8 cal. kyr BP. These episodes could have been related to the global climatic transition called the “4.2 ka event”, when the East Asian monsoon hydrological regime might have been altered. The cold episodes could be sufficiently severe to damage rice cultivation and their occurrence constitutes a plausible explanation for the demise of the Yangtze Neolithic civilization.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 201〈/p〉 〈p〉Author(s): Martina Hollstein, Mahyar Mohtadi, Yair Rosenthal, Matthias Prange, Delia W. Oppo, Gema Martínez Méndez, Kazuyo Tachikawa, Paola Moffa Sanchez, Stephan Steinke, Dierk Hebbeln〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Surface and thermocline conditions of the Western Pacific Warm Pool (WPWP) reflect changes in regional and basin scale ocean and atmosphere circulations and in turn may affect climate globally. Previous studies suggest that a range of factors influences the WPWP on different timescales, however the precise forcings and mechanisms are unclear. Combining surface and thermocline records from sediment cores offshore Papua New Guinea we explore the influence of local and remote processes on the WPWP in response to astronomical forcing and changing glacial-interglacial boundary conditions over the past 110 kyr. We find that thermocline temperatures change with variations in Earth's obliquity with higher temperatures coinciding with high obliquity, which is attributed to variations in subduction and advection of the South Pacific Tropical Water. In contrast, rainfall variations associated with meridional migrations of the Intertropical Convergence Zone are primarily driven by changes in insolation due to precession. Records of bulk sedimentary Ti/Ca and foraminiferal Nd/Ca indicate an additional influence of obliquity, which, however, cannot unambiguously be related to changes in precipitation. Finally, our results suggest a thermocline deepening during the Last Glacial Maximum (LGM). A compilation of available proxy records illustrates a dipole-like pattern of LGM thermocline depth anomalies with a shoaling (deepening) in the northern (southern) WPWP. A comparison of the proxy compilation with an ensemble of Paleoclimate Model Intercomparison Project (PMIP) climate model simulations reveals that the spatial pattern of LGM thermocline depth anomalies is mainly attributable to a contraction of the Pacific Walker circulation on its western side.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 201〈/p〉 〈p〉Author(s): Jinzhao Liu, Zhisheng An〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Leaf wax δD〈sub〉〈em〉n〈/em〉-alkane〈/sub〉 values have been widely utilized in terrestrial paleoenvironmental research, and numerous studies have reported that leaf wax δD〈sub〉〈em〉n〈/em〉-alkane〈/sub〉 values were affected by a lot of factors. However, the current knowledge regarding the constructive relationships among these factors is still unclear. Based upon a limited compilation of available δD〈sub〉〈em〉n〈/em〉-alkane〈/sub〉 records from published literature across the world, we proposed a hierarchical framework of three-level controls on leaf wax δD〈sub〉〈em〉n〈/em〉-alkane〈/sub〉 values by using an Interpretive Structural Modeling (ISM). Precipitation δD, plant types and evapotranspiration are the first-level controls that serve as direct co-controls on leaf wax δD〈sub〉〈em〉n〈/em〉-alkane〈/sub〉 values in higher plants, on average contributing 47 ± 22%, 20 ± 9.8% and 33%, respectively. The proportions of different controls on leaf wax δD〈sub〉〈em〉n〈/em〉-alkane〈/sub〉 values vary significantly over the world, probably responsible for the across-site substantial variability of isotopic fractionation (ε〈sub〉app〈/sub〉) between leaf wax δD〈sub〉〈em〉n〈/em〉-alkane〈/sub〉 values and precipitation δD. Moreover, extra factors (e.g., salinity, aridity, seasonality etc.) and climate parameters (e.g., temperature, relative humidity, light intensity etc.) execute the second-level and third-level controls on leaf wax δD〈sub〉〈em〉n〈/em〉-alkane〈/sub〉 values, respectively. They play indirect controls, through affecting the first-level controls, and thus are translated into leaf wax δD〈sub〉〈em〉n〈/em〉-alkane〈/sub〉 values. To quantitatively disentangle these controls on leaf wax δD〈sub〉〈em〉n〈/em〉-alkane〈/sub〉 values is important for better understanding the spatial-temporal variability of sedimentary δD〈sub〉〈em〉n〈/em〉-alkane〈/sub〉 values.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0277379118306383-fx1.jpg" width="389" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 201〈/p〉 〈p〉Author(s): Ian Shennan, Martin D. Brader, Natasha L.M. Barlow, Frank P. Davies, Chris Longley, Neil Tunstall〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We report stratigraphic evidence of land-level changes along the eastern portion of the Alaska-Aleutian megathrust. Four marshes on Shuyak Island record variable amounts of coseismic deformation during four pre-20th century earthquakes. We combine these data with paleoseismic evidence from across the Kodiak, Kenai and Prince William Sound segments of the megathrust. These indicate that in the last 2000 years, AD 1964 was the only one to rupture all three segments simultaneously and generate a M〈sub〉w〈/sub〉 9.2 earthquake. The Kodiak segment ruptured independently on four further occasions with magnitudes 〉 M〈sub〉w〈/sub〉 8.0; in AD 1788 and c.400 (440–320) BP, and independently but around the times of great earthquakes in the Prince William Sound segment c.850 and c.1500 BP.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0277379118305468-fx1.jpg" width="308" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 8 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Yolanda Carrión Marco, Pere Guillem Calatayud, Aleix Eixea, Carmen M. Martínez-Varea, Carmen Tormo, Ernestina Badal, João Zilhão, Valentín Villaverde〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Abrigo de la Quebrada rock shelter was occupied by Neanderthal groups during the early Upper Pleistocene, yielding evidence for their subsistence practices and local resource exploitation. This paper focuses on the plant macroremains and the micromammals, which provide information about occupation patterns, the surrounding landscape, the use of resources, and the environment. Mountain pine forests and permanent grass formations containing humid zones and open spaces that would have harboured an eurythermal microfauna were the dominant landscape type. Cold-climate pines provided most of the firewood. The data are consistent with a recurrent, seasonal occupation pattern, in which the rock shelter was used for short periods in the context of an annual round characterized by a high degree of mobility.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 204〈/p〉 〈p〉Author(s): Federico Di Rita, Gianluca Sottili〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Diatomite deposits in the Sabatini Volcanic District (central Italy) represent valuable archives to investigate both Middle Pleistocene vegetation dynamics and geochemistry of proximal products of volcanic eruptions, which provide crucial geochronological markers for a large region of Southern Europe. We present a new pollen record from a diatomite deposit at Rignano Flaminio, attributed to MIS 13 based on two major eruptive events from Monti Sabatini: the 〈em〉Grottarossa Pyroclastic Sequence〈/em〉 (513 ± 3 ka) and the 〈em〉Fall A〈/em〉 unit (499 ± 3 ka). We also add insights into the geochemical and mineralogical composition of the proximal deposits of the 〈em〉Fall A〈/em〉 tephra, whose products are found in several sites of the central Mediterranean. Our pollen record shows marked vegetation turnovers, reflecting changes in regional and global climate conditions, local environmental factors and ecological processes within refuge areas. The lower part of the record points to a forested environment dominated by both deciduous and evergreen broadleaved taxa, indicating wet and temperate climate conditions. This interval was punctuated by two phases of slight forest declines, where a general increase in Poaceae and 〈em〉Artemisia〈/em〉, coupled with the development of Ericaceae and evergreen 〈em〉Quercus〈/em〉 communities, suggests the establishment of mediterranean-type climatic conditions with increased aridity. The upper part of the sequence shows the development of 〈em〉Abies〈/em〉 and 〈em〉Pinus〈/em〉 woodlands, reflecting a change towards cooler and possibly wetter climate. The pollen richness, accompanied by a fossil leaf of 〈em〉Laurus〈/em〉, confirms the role of the Sabatini Volcanic District as a Pleistocene biodiversity hot-spot and refuge area for many trees.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 204〈/p〉 〈p〉Author(s): Samuli Helama, Pekka Saranpää, Charlotte L. Pearson, Laura Arppe, Jari Holopainen, Harri Mäkinen, Kari Mielikäinen, Pekka Nöjd, Raimo Sutinen, Jussi-Pekka Taavitsainen, Mauri Timonen, Joonas Uusitalo, Markku Oinonen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Frost rings can provide direct evidence of anomalously cold summertime conditions on hemispheric scales. Here we report frost rings in subfossil pinewood from Finnish Lapland dated dendrochronologically to AD 536 and 1627 BC. These exact calendar dates have been vividly discussed in the literature in the respective contexts of a cold climate anomaly/dust veil/crop failure/famine/Justinianic Plague and the Minoan eruption of Thera (Santorini). Coinciding anomalies in growth and carbon isotope ratios (δ〈sup〉13〈/sup〉C) indicate cold and overcast conditions in these years in Finnish Lapland, typical to conditions induced by volcanic dust veils. This evidence reinforces the view of multiple climatic drivers strongly effecting contemporary societies around AD 536 and provides important new evidence regarding the 1627 BC event. We report a frost ring for this year, and also consider evidence from Lapland for other Thera candidate eruptions in the 16th century BC. The marker years 1560 BC and 1546 BC in bristlecone pine tree rings in North America are positioned within negative departures in our δ〈sup〉13〈/sup〉C data. Most likely, the frosts occurred somewhere in July and were driven by dust veils from Northern Hemisphere. Although not indicative of volcanic provenance, frost rings and other dendroclimatic proxies dated to exact calendar years offer important time markers for chronological frameworks which can synchronize archaeological, historical and environmental data to further our understanding of environmental changes at scales that matter to human societies.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 204〈/p〉 〈p〉Author(s): C.W. Kemp, J. Tibby, L.J. Arnold, C. Barr〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Improved reconstructions of Australia's climate during Marine Isotope Stage 3 (MIS 3) are important for understanding the environmental context of widespread human settlement of the continent and the extinction of a wide range of megafauna by 45 ± 5 thousand years ago (ka). To better understand spatial and temporal climate trends during this period, we present a synthesis of hydroclimate data from 40 Australian MIS 3 records. Hydroclimate records were evaluated and weighted by a scoring system developed to evaluate dating and proxy quality and resolution before inclusion into the synthesis. Our analysis reveals that Australia experienced spatially variable climates from ∼57 to 49 ka before becoming predominantly wet from ∼49 to 40 ka. After ∼40 ka increasingly dry climates dominated MIS 3. Records from monsoon-influenced regions indicate a rapid drying from ∼48 ka to the end of MIS 3, while there was a wetter period from ∼50 to 40 ka in south westerly wind-influenced records. The implications of our findings are discussed in relation to other proxy records, with there being a significant relationship with regional fire history, but little correlation to atmospheric CO〈sub〉2〈/sub〉 concentration or global sea level.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 204〈/p〉 〈p〉Author(s): Géraldine Fiers, Sebastien Bertrand, Maarten Van Daele, Emma Granon, Brian Reid, Willem Vandoorne, Marc De Batist〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Lago Castor (45°S) contains a continuous sediment record of Patagonian climate and environmental change during the last 20 kyr. Here, we use the bulk elemental and isotopic composition of the organic matter preserved in Lago Castor sediments to reconstruct changes in the supply of organic carbon of terrestrial and aquatic origin to the lake through time. Results show that the lake sedimentary organic matter is composed of variable proportions of lake plankton, terrestrial vegetation, and aquatic macrophytes. Before 17.8 cal kyr BP, aquatic macrophytes were abundant, likely due to the low but rising postglacial lake level. After 17.8 cal kyr BP, accumulation rates of organic carbon of aquatic macrophyte origin became negligible, whereas those of terrestrial origin increased, reflecting weak westerlies and terrestrial vegetation development under a milder climate, respectively. From 9.3 cal kyr BP onwards, accumulation rates of organic carbon from both aquatic macrophytes and terrestrial vegetation increased and peaked between 7.5 and 2.0 cal kyr BP. The latter is interpreted as a period of increased wind strength and precipitation, and is in excellent agreement with the grain-size results previously obtained on the same sediment core. All proxies show a secondary increase in wind strength and precipitation during the last millennium, in agreement with regional high-resolution records of the last 2000 years. These results, which are broadly compatible with regional pollen records during the Holocene, suggest that, at 45°S, the westerlies reached their maximum intensity between 7.5 and 2.0 cal kyr BP and increased again during the last millennium.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0277379118305675-fx1.jpg" width="315" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 1 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Adriana Moroni, Giovanni Boschian, Jacopo Crezzini, Guido Montanari-Canini, Giulia Marciani, Giulia Capecchi, Simona Arrighi, Daniele Aureli, Claudio Berto, Margherita Freguglia, Astolfo Araujo, Sem Scaramucci, Jean Jacques Hublin, Tobias Lauer, Stefano Benazzi, Fabio Parenti, Marzia Bonato, Stefano Ricci, Sahra Talamo, Aldo G. Segre〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Most of the Middle Palaeolithic evidence of Central Italy still lacks a reliable chrono-cultural framework mainly due to research history. In this context Grotta dei Santi, a wide cave located on Monte Argentario, on the southern coast of Tuscany, is particularly relevant as it contains a very well preserved sequence including several Mousterian layers. Research carried out at this site in the last years (2007–2017) allowed for a preliminary estimation of its chronology based on a set of radiometric determinations which place the investigated sequence in the time interval between 50 and 40 ka BP. Alongside the chronological issue, this paper mainly focuses on the geoarchaeological and zooarchaeological (micro and macro fauna) studies carried out on the materials retrieved during the 2007–2014 excavation fieldworks. The results of these studies are consistent with those from the radiometric chronology. A state of art concerning the MIS3 Italian sites is also provided in order to highlight the key role Grotta dei Santi may play in the assessment of late Neandertals’ behaviour within the framework of the Middle to Upper Palaeolithic transition of Central Italy.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 203〈/p〉 〈p〉Author(s): David García-Moreno, Sanjeev Gupta, Jenny S. Collier, Francesca Oggioni, Kris Vanneste, Alain Trentesaux, Koen Verbeeck, Wim Versteeg, Hervé Jomard, Thierry Camelbeeck, Marc De Batist〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Prominent landforms, either buried or preserved at the seafloor, provide important constraints on the processes that led to the opening and present-day configuration of the Dover Strait. Here, we extend previous investigations on two distinct landform features, the Fosse Dangeard and Lobourg Channel, to better understand the poly-phase history of their formation and inferences for the opening and Pleistocene evolution of the Dover Strait.〈/p〉 〈p〉The Fosse Dangeard consist of several interconnected palaeo-depressions. Their morphology and spatial distribution are interpreted to be the result of plunge-pool erosion generated at the base of north-eastward retreating waterfalls. Their infills comprise internal erosional surfaces that provide evidence for the occurrence of several erosional episodes following their initial incision.〈/p〉 〈p〉The Lobourg Channel comprises various sets of erosional features, attesting to the occurrence of several phases of intense fluvial and/or flood erosion. The last one of these carved a prominent inner channel, which truncates the uppermost infill of the Fosse Dangeard. The morphology of the Lobourg inner channel and the erosional features associated with its incision strongly resemble landforms found in megaflood-eroded terrains, indicating that this valley was likely eroded by one or several megafloods.〈/p〉 〈p〉Our study therefore corroborates the existence of waterfalls in the Dover Strait at least once during the Pleistocene Epoch. It also provides evidence of the occurrence of multiple episodes of fluvial and flood erosion, including megafloods. Finally, this study allows us to establish a relative chronology of the erosional/depositional episodes that resulted in the present-day morphology of this region.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 203〈/p〉 〈p〉Author(s): Shannon Klotsko, Neal Driscoll, Lloyd Keigwin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The first regional model for the deglacial history of the Beaufort margin slope, in the western Arctic, is presented. The conceptual model was developed using new high-resolution CHIRP seismic reflection, multibeam bathymetry, and sediment core data acquired along the margin. This synthesis provides important constraints on sediment source and dispersal patterns for the last deglaciation. The continental slope from Barrow Canyon to the Mackenzie Trough is characterized by thick Holocene sediments mostly sourced from Barrow Canyon and continental discharge. This acoustically transparent, fine-grained unit overlies acoustically laminated sediments sourced from the Mackenzie River and ice rafting. The deglacial history of the margin from Mackenzie Trough to the Amundsen Gulf is characterized by many ice rafting and meltwater discharge events. Ice rafted debris layers were deposited around ∼14.6 ka and ∼14.1 ka and likely document enhanced ice shedding events from the Amundsen and M'Clure ice streams as they retreated. There are three inferred meltwater discharge events, all sourced from the Mackenzie region. The oldest discharge event had two phases, one sometime between ∼14.5 ka and ∼14.2 ka and another between ∼14.0 ka and ∼13.0 ka. This discharge deposited finely laminated sediments more than 7 m thick sourced from proglacial lakes in the area. Following this was a flood event starting at ∼12.94 ka, which generated high amplitude reflectors, deposited coarse debris, and caused a lowering in the δ〈sup〉18〈/sup〉O record. This is possibly a major outburst flood from glacial Lake Agassiz with an additional component of Agassiz meltwater that was diverted from its southern drainage pathway down the Mississippi to the Gulf of Mexico. Finally, a third discharge event was initiated by ∼11.3 ka, which deposited coarse laminated sediments focused in the Mackenzie Trough. Timing of these second and third events correlates with the onset of the Younger Dryas cold period and the preBoreal oscillation event, respectively, suggesting that fresh water discharge may have reached a tipping point, leading to those climate events.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews, Volume 204〈/p〉 〈p〉Author(s): S. Kutterolf, J.C. Schindlbeck, M. Jegen, A. Freundt, S.M. Straub〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The increase in volcanic activity after the last glacial maximum observed on Iceland has led to one of the most fascinating hypothesis in science in the last decades: that deglaciation may force volcanism. Consequently, tephrostratigraphic records of sufficient length that cover multiple glacial cycles have been used to test whether such relationships hold systematically through the Quaternary. Here we review such tephra records that have been linked with climate proxy records such as δ〈sup〉18〈/sup〉O in marine sediments, which is a measure of sea-level change and which is thought to be orbitally forced, as it exhibits the characteristic Milankovitch periodicities of precession (∼23 kyr), obliquity (∼41 kyr) and eccentricity (∼100 kyr).〈/p〉 〈p〉Statistical analyses have identified these periodicities also in long tephra records from different latitudes and geotectonic settings, as well as in compiled semi-global records. These studies detect Milankovitch periods in their tephra record, and also a phase shift relative to the δ〈sup〉18〈/sup〉O record in such that periods of increased eruption frequencies coincide with the deglaciation period at the glacial/interglacial transition when ice and water loads on the lithosphere change most rapidly. However, there are also disparities in results and interpretations, which may be attributable to the different methods of analysis applied by the studies.〈/p〉 〈p〉We have therefore re-analyzed the four best-characterized tephra records by the same methods. We distinguish between analysis in the frequency domain, a novel approach, and analysis in the time domain, which has been used in previous studies. Analysis in the frequency domain identifies harmonic frequencies that arise from the binary nature of the tephra records and complicate the identification of primary frequencies. However, we show that all four records show spectral density peaks near the main Milankovitch periodicities of 41 and 100 kyr, and that they produce meaningful and significant statistical correlations with each other and the global δ〈sup〉18〈/sup〉O record but not with random time series. Although the time-domain correlations with δ〈sup〉18〈/sup〉O roughly confirm phase shifts implying peak volcanism during deglaciation, correlation coefficients arising from very noisy records are generally too low for precise constraints on the relative timing.〈/p〉 〈p〉These deficiencies presently hamper the recognition of the physical mechanisms through which global climate changes affect volcanism at both, high-latitude glaciated regions and low-latitude non-glaciated regions.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 23 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): Warren J. Eastwood, Andrew Fairbairn, Elizabeth Stroud, Neil Roberts, Henry Lamb, Hakan Yiğitbaşıoğlu, Çetin Şenkul, Andrew Moss, Rebecca Turner, Peter Boyer〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Establishing agricultural activity using pollen analysis is one of the prime challenges of a palaeoecological investigation. Here we report combined pollen and archaeobotanical data originating from a waterlogged off-site organic-rich fill radiocarbon dated to ∼8 ka Cal BP located between the two occupation mounds at Neolithic-Chalcolithic Çatalhöyük, south central Turkey in order to investigate the record of Early Chalcolithic agricultural activity. Pollen results indicate extremely high abundances of Cerealia-type pollen (30-〉70%) and critical measurements of these show them to be 〈em〉Triticum〈/em〉-type, 〈em〉Avena〈/em〉/〈em〉Triticum〈/em〉-type, 〈em〉Secale〈/em〉-type and 〈em〉Hordeum〈/em〉-type. Pollen data are also compared with archaeobotanical data retrieved from the same sediment matrix and show high abundances of 〈em〉Triticum〈/em〉 and 〈em〉Hordeum〈/em〉 grains, awns, spikelet forks and glume bases. Archaeobotanical and pollen data are therefore unequivocal in showing the presence of cereals throughout the period of deposition, and although preservation of archaeobotanical cereal plant remains is typically poor, the presence of glume wheats, including emmer/‘New Type’ wheat and domesticated barley, is consistent with cereal data from on-site excavation deposits at Çatalhöyük. Pollen data also include high occurrences of clusters of Cerealia-type, Chenopodiaceae, Poaceae and Asteraceae and point to local deposition that is best explained as the anthers being deposited at the coring site attached to cereal or other herbaceous waste material. Archaeobotanical data in addition to very high percentage values of individual Cerealia-type pollen grains and clusters of Cerealia-type pollen and other non-arboreal pollen types suggest that the margins of the Çatalhöyük site were probably used for early stage crop processing activities as well as a waste site. Although radiocarbon dating of this organic-rich fill suggests that it was deposited over a very short time period (∼300 years) during the Early Chalcolithic, the data highlight the importance of adopting complementary palynological and archaeobotanical approaches in order to better understand the taphonomy of micro and macrofossil deposits associated with archaeological sites. While more distant, regional pollen sites in south-central Anatolia have difficulty registering Neolithic-Chalcolithic cereal cultivation, this study shows that if a pollen core site is located too close to an archaeological site, then pollen assemblages can be overwhelmed and ‘swamped’ by the products of local cereal processing and the inclusion of domestic waste material thus rendering it difficult to elucidate meaningful data on local agricultural activity.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 22 November 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Quaternary Science Reviews〈/p〉 〈p〉Author(s): José S. Carrión, Michael J. Walker〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper provides a background to Neanderthal presence in Western Mediterranean Europe. Habitual tool-use underpinned human survival in late Early Pleistocene western Mediterranean Europe. By the onset of the early Middle Pleistocene, early humans (descendants of 〈em〉Homo antecessor〈/em〉 in all likelihood) were exploiting diverse biotopes, sometimes (perhaps often) attaining primary access to large game, and deploying a variety of stone artifacts and rock types, which implies not only manual dexterity but also technical competence and cognitive versatility. Late Early Pleistocene human behaviour foreshadowed that of Middle Pleistocene pre-Neanderthal humans whose background conceivably had deep regional roots. By the mid-Middle Pleistocene 〈em〉Homo heidelbergensis〈/em〉, some of whose anatomical features herald Neanderthal morphology, was exploiting a wide range of natural resources in western Mediterranean environments, including small game and plants. Neanderthal morphology began to emerge during the second half of the Middle Pleistocene, accompanied by increasing technological diversity and an expanding variety of small tools, conjecturally favoured by hafting, perhaps following development of wooden spears (or other tools) and adhesive and binding technologies, and generation and heat-control of fire (which undoubtedly was necessary for activities inside Bruniquel cave). By the onset of the last interglacial period, Neanderthal morphology and Mousterian artifacts are widespread, and there are indications of coordinated retrieval and treatment of body-parts of large ungulates.〈/p〉〈/div〉 〈/div〉