ALBERT

Beschreibung: Publication date: Available online 24 September 2013 Source: Quaternary Research Author(s): Daniel E. Karig , Norton G. Miller Areal mapping of the middle Wisconsin varved clay site along Sixmile Creek near Ithaca, New York, has revealed a much more widespread and varied array of sediments than previously thought. Lacustrine clays, some varved, are interbedded with sands and gravels interpreted as sub-aqueous fan deposits, and both are overlain by a deformation till. Nine radiocarbon dates indicate a 34–37 14 C ka BP age for the lacustrine sediment, with the deformation till less than a few thousand years younger. Beneath this sequence is a deposit dated at ± 42 14 C ka BP. Both strata represent a tundra climate with a mean July temperature of about 10°C. The Sixmile Creek deformation till must correlate with the 35 14 C ka BP till along the Genesee River, 125 km to the NW, and defines a Cherrytree stade glacial advance into the Appalachian Plateau, much further south than what has generally been accepted. Such an advance would require drainage from a proglacial lake in the western Ontario basin to flow westward instead of northeastward. The Sixmile strata suggest a colder than accepted middle Wisconsin stage. Recent data indicate that this stage is one of progressive cooling, with large climatic fluctuations.

Beschreibung: Publication date: Available online 25 September 2013 Source: Quaternary Research Author(s): Denis Geraads , Fethi Amani , Abdelouahed Ben-Ncer , Shannon P. McPherron , Jean-Paul Raynal , Jean-Jacques Hublin The rodents from the late middle Pleistocene hominin-bearing locality of J'bel Irhoud include the following species: Meriones shawii , Gerbillus grandis , Dipodillus campestris , Paraethomys ras , Lemniscomys barbarus , Mus cf. spretus , and Eliomys sp. We consider M. shawii , a living species, as identical with the middle Pleistocene Meriones maghrebianus . The mouse differs from the domestic Mus musculus but does not clearly fit into Mus spretus , either. The rare G. grandis looks identical with the form from the middle Pleistocene of Thomas quarries, which may suggest a rather early age for Irhoud. This is in agreement with the occurrence of Paraethomys , a genus unknown in the upper Pleistocene of Morocco, but the absence of the arvicolid Ellobius suggests that the site is younger than other middle Pleistocene sites, Doukkala II, Sidi Abderrahmane D2, and Irhoud-Derbala-Virage. Paleoecological indicators, such as the taxonomic habitat spectrum, or the relative abundances of Gerbillinae and Murinae, suggest a less xeric environment than in many earlier and later sites. Diversity indices, comparable to those of other middle Pleistocene sites, point to similarly favorable conditions before the major climatic crisis close to the middle/upper Pleistocene boundary that drastically reduced rodent diversity in North Africa.

Beschreibung: Publication date: Available online 25 September 2013 Source: Quaternary Research Author(s): Mikael Ohlson , Isabella Kasin , Anveig Nordtug Wist , Anne E. Bjune Forest fires convert a proportion of the burning vegetation into charcoal that is stored in forest soils and lake sediments. In this paper we use a geostatistical approach to present a detailed analysis of the size of the charcoal pool and its spatial variation in a boreal forest watershed including its lake sediment. The amount of soil charcoal averaged 179 g/m 2 and ranged from 0 to 3600 g/m 2 in the watershed. There was an extreme variation in the size of the charcoal pool over fine (cm) spatial scales. For example, the amount of charcoal in the soil could range from 34 to 1646 g/m 2 within a distance of 10 cm. Individually dated soil charcoal particles had radiocarbon ages that varied from 630 to 2930 cal yr BP. The lake sediment began accumulating at 10,600 cal yr BP and charcoal accumulation has been practically continuous ever since then, with the largest peak occurring at 6900 cal yr BP. The lake sediment contained more charcoal, 360 g/m 2 , than the average for forest soil. We interpret this as an indication of a relatively rapid degradation of charcoal in boreal forest soils.

Beschreibung: Publication date: Available online 29 September 2013 Source: Quaternary Research Author(s): Julien Carcaillet , Isandra Angel , Eduardo Carrillo , Franck A. Audemard , Christian Beck In the tropical Mérida Andes (northwestern Venezuela), glacial landforms were found at altitudes between 2600 and 5000 m, corresponding to 600 km 2 of ice cover during the maximum glacial extension. However, the lack of sufficient absolute age data prevents detailed reconstruction of the timing of the last deglaciation. On the northwestern flank of the Mucuñuque Massif, successive moraines and striated eroded basement surfaces were sampled for cosmogenic 10 Be investigation. Their compilation with published data allows the establishment of a detailed chronology of the post-LGM glacier history. The oldest moraines (18.1 and 16.8 ka) correspond to the Oldest Dryas. Successive moraine ridges indicate stops in the overall retreat between the LGM and the Younger Dryas. The cold and short Older Dryas stadial has been identified. Results indicate that most of the ice withdrew during the Pleistocene. The dataset supports an intensification of the vertical retreat rate from ~ 25 m/ka during the late Pleistocene to ~ 310 m/ka during the Pleistocene/Holocene. Afterwards, the glacier was confined and located in the higher altitude zones. The altitude difference of the Younger Dryas moraines in the Mucubají, La Victoria and Los Zerpa valleys indicates a strong effect of valley orientation on the altitude of moraine development.

Beschreibung: Publication date: Available online 3 October 2013 Source: Quaternary Research Author(s): Nicole E. Spaulding , John A. Higgins , Andrei V. Kurbatov , Michael L. Bender , Steven A. Arcone , Seth Campbell , Nelia W. Dunbar , Laura M. Chimiak , Douglas S. Introne , Paul A. Mayewski Terrestrial meteorite ages indicate that some ice at the Allan Hills blue ice area (AH BIA) may be as old as 2.2 Ma. As such, ice from the AH BIA could potentially be used to extend the ice core record of paleoclimate beyond 800 ka. We collected samples from 5 to 10 cm depth along a 5 km transect through the main icefield and drilled a 225 m ice core (S27) at the midpoint of the transect to develop the climate archive of the AH BIA. Stable water isotope measurements (δD) of the surface chips and of ice core S27 yield comparable signals, indicating that the climate record has not been significantly altered in the surface ice. Measurements of 40 Ar atm and δ 18 O atm taken from ice core S27 and eight additional shallow ice cores constrain the age of the ice to approximately 90–250 ka. Our findings provide a framework around which future investigations of potentially older ice in the AH BIA could be based.

Beschreibung: Publication date: Available online 3 October 2013 Source: Quaternary Research Author(s): Yurena Yanes , María P. Asta , Miguel Ibáñez , María R. Alonso , Christopher S. Romanek Land snail shell δ 13 C value is often used as a paleovegetation proxy assuming that snails ingest all plants in relation to their abundance, and that plants are the only source of carbon. However, carbonate ingestion and variable metabolic rates complicate these relationships. We evaluate if live-collected snails from Lanzarote (Canary Islands) reflect the abundance of C 3 and CAM plants. Snails were collected on either CAM or C 3 plants for isotope analysis of shell and body, and shell size. Respective shell and body δ 13 C values of snails collected on CAM plants averaged − 8.5 ± 1.7‰ and − 22.8 ± 1.6‰, whereas specimens from C 3 plants averaged − 10.1 ± 0.7‰ and − 24.9 ± 1.1‰. A flux balance model suggests snails experienced comparable metabolic rates. A two-source mass balance equation implies that snails consumed ~ 10% of CAM, which agrees with their abundance in the landscape. Snails collected on CAM plant were smaller than those on C 3 plants. Conclusively: 1) snails consume CAM plants when they are available; 2) migration of snails among C 3 and CAM plants is a common phenomenon; and 3) C 3 plants may be a more energetic food for growth than CAM plants. This study shows that shell δ 13 C values offer approximate estimates of plants in C 3 –CAM mixed environments.

Beschreibung: Publication date: Available online 7 June 2013 Source: Quaternary Research Author(s): William R. Dickinson Unlike most tropical Pacific islands, which lie along island arcs or hotspot chains, the Loyalty Islands between New Caledonia and Vanuatu owe their existence and morphology to the uplift of pre-existing atolls on the flexural forebulge of the New Hebrides Trench. The configuration and topography of each island is a function of distance from the crest of the uplifted forebulge. Both Maré and Lifou are fully emergent paleoatolls upon which ancient barrier reefs form highstanding annular ridges that enclose interior plateaus representing paleolagoon floors, whereas the partially emergent Ouvea paleoatoll rim flanks a drowned remnant lagoon. Emergent paleoshoreline features exposed by island uplift include paleoreef flats constructed as ancient fringing reefs built to past low tide levels and emergent tidal notches incised at past high tide levels. Present paleoshoreline elevations record uplift rates of the islands since last-interglacial and mid-Holocene highstands in global and regional sea levels, respectively, and paleoreef stratigraphy reflects net Quaternary island emergence. The empirical uplift rates vary in harmony with theoretical uplift rates inferred from the different positions of the islands in transit across the trench forebulge at the trench subduction rate. The Loyalty Islands provide a case study of island environments controlled primarily by neotectonics.

Beschreibung: Publication date: Available online 7 June 2013 Source: Quaternary Research Author(s): Thomas R. Lakeman , John H. England The study revises the maximum extent of the northwest Laurentide Ice Sheet (LIS) in the western Canadian Arctic Archipelago (CAA) during the last glaciation and documents subsequent ice sheet retreat and glacioisostatic adjustments across western Banks Island. New geomorphological mapping and maximum-limiting radiocarbon ages indicate that the northwest LIS inundated western Banks Island after ~ 31 14 C ka BP and reached a terminal ice margin west of the present coastline. The onset of deglaciation and the age of the marine limit (22–40 m asl) are unresolved. Ice sheet retreat across western Banks Island was characterized by the withdrawal of a thin, cold-based ice margin that reached the central interior of the island by ~ 14 cal ka BP. The elevation of the marine limit is greater than previously recognized and consistent with greater glacioisostatic crustal unloading by a more expansive LIS. These results complement emerging bathymetric observations from the Arctic Ocean, which indicate glacial erosion during the Last Glacial Maximum (LGM) to depths of up to 450 m.

Beschreibung: Publication date: Available online 10 April 2013 Source: Quaternary Research The distribution of marine-influenced oxygen isotope stage (OIS) 5 to OIS 1 sediments was examined in several late Quaternary boreholes from the southern Changjiang (Yangtze) delta plain, China, using different dating methods including OSL, U-series, AMS 14 C and paleomagnetism. Results demonstrate that coastal and estuarine deposition during OIS 5 and OIS 3 occurred throughout the study area. However, Holocene transgressive sediments were absent on the Taihu block. The burial depth of intertidal to subtidal sediment deposited during OIS 5e records 30–80 m subsidence caused by sediment compaction and tectonic movement since that time. However, coastal sediments formed during the late phase of OIS 3 were buried to a depth of ca. 6–15 m in the Taihu Lake area, while the burial depth increased eastward to ca. 45–60 m on the coastal plain. This phenomenon, combined with the distribution of Holocene marine strata, indicates at least 25–30 m uplift of the Taihu block since the end of OIS 3. We suggest that this uplift was mainly caused by the differential subsidence due to substantial amount of post-glacial deposition by the Changjiang and Huanghe Rivers on the continental shelf of east China marginal sea.

Beschreibung: Publication date: Available online 5 September 2013 Source: Quaternary Research Author(s): Vachel A. Carter , Andrea Brunelle , Thomas A. Minckley , Philip E. Dennison , Mitchell J. Power Fire is one of the most important natural disturbances in the coniferous forests of the US Rocky Mountains. The Rocky Mountains are separated by a climatic boundary between 40° and 45° N, which we refer to as the central Rocky Mountains (CRM). To determine whether the fire regime from the CRM was more similar to the northern Rocky Mountains (NRM) or southern Rocky Mountains (SRM) during the Holocene, a 12,539-yr-old sediment core from Long Lake, Wyoming, located in the CRM was analyzed for charcoal and pollen. These data were then compared to charcoal records from the CRM, NRM and SRM. During the Younger Dryas chronozone, the fire regime was characterized as frequent at Long Lake. The early and middle Holocene fire regime was characterized as infrequent. A brief interval from 4000 to 3000 cal yr BP, termed the Populus period, had a frequent fire regime and remained frequent through the late Holocene at Long Lake. In comparison to sites from the NRM and SRM, the fire regime at Long Lake was most similar to the SRM during the past 12,539 cal yr BP. These results suggest the disturbance regime in the CRM has a greater affinity with those of the SRM.

Beschreibung: Publication date: Available online 13 September 2013 Source: Quaternary Research Author(s): Lyudmila S. Shumilovskikh , Helge W. Arz , Antje Wegwerth , Dominik Fleitmann , Fabienne Marret , Norbert Nowaczyk , Pavel Tarasov , Hermann Behling This multiproxy study on SE Black Sea sediments provides the first detailed reconstruction of vegetation and environmental history of Northern Anatolia between 134 and 119 ka. Here, the glacial–interglacial transition is characterized by several short-lived alternating cold and warm events preceding a meltwater pulse (~ 130.4–131.7 ka). The latter is reconstructed as a cold arid period correlated to Heinrich event 11. The initial warming is evidenced at ~ 130.4 ka by increased primary productivity in the Black Sea, disappearance of ice-rafted detritus, and spreading of oaks in Anatolia. A Younger Dryas-type event is not identifiable. The Eemian vegetation succession corresponds to the main climatic phases in Europe: i) the Quercus – Juniperus phase (128.7–126.4 ka) indicates a dry continental climate; ii) the Ostrya – Corylus – Quercus – Carpinus phase (126.4–122.9 ka) suggests warm summers, mild winters, and high year-round precipitation; iii) the Fagus – Carpinus phase (122.9–119.5 ka) indicates cooling and high precipitation; and iv) increasing Pinus at ~ 121 ka marks the onset of cooler/drier conditions. Generally, pollen reconstructions suggest altitudinal/latitudinal migrations of vegetation belts in Northern Anatolia during the Eemian caused by increased transport of moisture. The evidence for the wide distribution of Fagus around the Black Sea contrasts with the European records and is likely related to climatic and genetic factors.

Beschreibung: Publication date: Available online 26 September 2013 Source: Quaternary Research Author(s): Liubing Xu , Shangzhe Zhou The timing of terrace formation relative to the glacial–interglacial cycle and what factors control that timing, such as changes in climate and/or uplift, are controversial. Here we present a study of the terraces along the Yazheku River using electron spin resonance (ESR) dating and analysis of the sedimentary characteristics in order to establish the timing of terrace formation and to assess the forcing mechanisms that have been proposed. The Yazheku River flows in glacial trough leading from the Haizi Shan, on the eastern Tibetan Plateau. The range was uplifted during the Quaternary and repeatedly glaciated by ice caps. The four highest major terraces (T5, T4, T3, and T2) are the result of both climatic and tectonic influences. Strath terraces T5–T2 were created during Haizi Shan glacial expansions during MIS 16, 12, 6 and 3–4, respectively. The major aggradation phases of the four terraces occurred during the deglaciations at the ends of MIS 16, 12, 6, and 2. Down-cutting, which led to the generation of the four terraces, immediately followed the deposition of the T5–T2 gravel units. These incisions occurred during the transitions between MIS 16–15, MIS 12–11, MIS 6–5, and MIS 2–1.

Beschreibung: Publication date: Available online 16 December 2014 Source: Quaternary Research Author(s): Marith C. Reheis , David M. Miller , John P. McGeehin , Joanna R. Redwine , Charles G. Oviatt , Jordon Bright An outcrop-based lake-level curve, constrained by ~ 70 calibrated 14 C ages on Anodonta shells, indicates at least 8 highstands between 45 and 25 cal ka BP within 10 m of the 543-m upper threshold of Lake Manix in the Mojave Desert of southern California. Correlations of Manix highstands with ice, marine, and speleothem records suggest that at least the youngest three highstands coincide with Dansgaard–Oeschger (D–O) stadials and Heinrich events 3 and 4. The lake-level record is consistent with results from speleothem studies in the Southwest that indicate cool wet conditions during D–O stadials. Notably, highstands between 43 and 25 ka apparently occurred at times of generally low levels of pluvial lakes farther north as interpreted from core-based proxies. Mojave lakes may have been supported by tropical moisture sources during oxygen-isotope stage 3, perhaps controlled by southerly deflection of Pacific storm tracks due to weakening of the sea-surface temperature gradient in response to North Atlantic climate perturbations.

Beschreibung: This article is currently available as a free download on ingentaconnect

Beschreibung: This article is currently available as a free download on ingentaconnect

Beschreibung: This article is currently available as a free download on ingentaconnect

Beschreibung: This article is currently available as a free download on ingentaconnect

Beschreibung: Publication year: 2011 Source: Quaternary Research, In Press, Corrected Proof, Available online 8 June 2011 David J., Mallinson , Curtis W., Smith , Shannon, Mahan , Stephen J., Culver , Katie, McDowell The Outer Banks barrier islands of North Carolina, USA, contain a geologic record of inlet activity that extends from ca. 2200calyr BP to the present, and can be used as a proxy for storm activity. Optically stimulated luminescence (OSL) dating (26 samples) of inlet-fill and flood tide delta deposits, recognized in cores and geophysical data, provides the basis for understanding the chronology of storm impacts and comparison to other paleoclimate proxy data. OSL ages of historical inlet fill compare favorably to historical documentation of inlet activity, providing confidence in the technique. Comparison suggests that the Medieval Warm Period (MWP) and...

Beschreibung: Publication year: 2011 Source: Quaternary Research, In Press, Corrected Proof, Available online 23 June 2011 Gregory C., Wiles , Daniel E., Lawson , Eva, Lyon , Nicholas, Wiesenberg , R.D., D'Arrigo Two interstadial tree ring-width chronologies from Geikie Inlet, Glacier Bay Southeast, Alaska were built from 40 logs. One of these chronologies has been calendar dated to AD 224–999 (775yr) crossdating with a living ring-width chronology from Prince William Sound, Alaska. Trees in this chronology were likely killed through inundation by sediments and meltwater from the advancing Geikie Glacier and its tributaries ca. AD 850. The earlier tree-ring chronology spans 545yr and is a floating ring-width series tied to radiocarbon ages of about 3000calyr BP. This tree-ring work indicates two intervals of glacial expansion by the Geikie Glacier system toward the...

Beschreibung: Publication year: 2011 Source: Quaternary Research, In Press, Corrected Proof, Available online 25 June 2011 Natalie M., Monacci , Ursula, Meier-Grünhagen , Bruce P., Finney , Hermann, Behling , Matthew J., Wooller This study examines a sediment core (SR-63) from a mangrove ecosystem along the Sibun River in Belize, which is subject to both changes in sea-level and in the characteristics of the river's drainage basin. Radiocarbon dates from the core show a decreased sedimentation rate from ~6ka to 1calka BP and a marked change in lithology from primarily mangrove peat to fluvial-derived material at ~2.5calka BP. Changes in the sedimentation rates observed in mangrove ecosystems offshore have previously been attributed to changes in relative sea-level and the rate of sea-level rise. Pollen analyses show a decreased abundance of Rhizophora (red mangrove)...

Beschreibung: Publication year: 2011 Source: Quaternary Research, In Press, Corrected Proof, Available online 8 June 2011 Jan-Hendrik, May , Jana, Zech , Roland, Zech , Frank, Preusser , Jaime, Argollo , ... Although glacial landscapes have previously been used for the reconstruction of late Quaternary glaciations in the Central Andes, only few data exist for the Eastern Cordillera in Bolivia. Here, we present results from detailed morphostratigraphic mapping and new data of surface exposure dating (SED), optically stimulated luminescence (OSL), and radiocarbon dating (14C) from the Huara Loma Valley, Cordillera de Cochabamba (Bolivia). Discrepancies between individual dating methods could be addressed within the context of a solid geomorphic framework. We identified two major glaciations. The older is not well constrained by the available data, whereas the younger glaciation is subdivided into at...

Beschreibung: Publication year: 2011 Source: Quaternary Research, In Press, Corrected Proof, Available online 12 June 2011 Roderick J., Bale , Iain, Robertson , Matthew W., Salzer , Neil J., Loader , Steven W., Leavitt , ... We present the first near millennium-length, annually resolved stable isotope record from bristlecone pines (Pinus longaeva, D.K Bailey). The carbon isotope ratios from the cellulose of seven trees from the White Mountains of California, corrected for anthropogenic changes in atmospheric chemistry, are used to reconstruct growing season (June through August) precipitation back to AD 1085. Extremely negative isotope results are strongly correlated with proposed severest El Niño events over the last 500yr, and similar values in the first half of the millennium are used to reconstruct a further 13 strong El Niño events, concentrated in the 12th Century and the...

Beschreibung: Publication year: 2011 Source: Quaternary Research, In Press, Corrected Proof, Available online 14 June 2011 Denis, Wirrmann , Anne-Marie, Sémah , Jean-Pierre, Debenay , Magali, Chacornac-Rault Multiproxy analysis of three littoral cores from western New Caledonia supports the hypothesis that the main controlling factors of environmental changes are sea-level change, ENSO variability and extra-tropical phenomena, such as the Medieval Warm Period (MWP) marked by a tendency for La Niña-like conditions in the tropical Pacific. The record starts during the late Holocene sea-level rise when the terrestrial vegetation indicated wet and cool conditions. The site was a coastal bay definitely transformed into a freshwater swamp at around 3400calyr BP, after the rapid drawdown of sea level to its current level. Sediments and foraminiferal assemblages indicated subsequent episodes...

Beschreibung: Publication year: 2011 Source: Quaternary Research, In Press, Corrected Proof, Available online 7 May 2011 Bryan Keith, Sell , Scott Douglas, Samson Geochemical correlation of ash-fall beds with conventional tephrochronologic methods is not feasible when original glass composition is altered. Thus, alternative correlation methods may be required. Initial studies of heavily altered Paleozoic tephra (K-bentonites) have suggested the potential for employing trace-element concentrations in apatite as ash-fall bed discriminators. To further test the utility of apatite trace-element tephrochronology, we analyzed apatite phenocrysts from unaltered volcanic rocks with an electron microprobe: nine samples from rocks erupted during the Quaternary and one sample from a rock erupted during the Paleogene. The resulting apatite trace-element data provide unique bed discriminators despite within-crystal variability. Each of...

Beschreibung: Publication year: 2011 Source: Quaternary Research, In Press, Corrected Proof, Available online 13 May 2011 Arjen P., Stroeven , Derek, Fabel , Jonathan M., Harbor , David, Fink , Marc W., Caffee , ... Deglaciation chronologies for some sectors of former ice sheets are relatively poorly constrained because of the paucity of features or materials traditionally used to constrain the timing of deglaciation. In areas without good deglaciation varve chronologies and/or without widespread occurrence of material that indicates the start of earliest organic radiocarbon accumulations suitable for radiocarbon dating, typically only general patterns and chronologies of deglaciation have been deduced. However, mid-latitude ice sheets that had warm-based conditions close to their margins often produced distinctive deglaciation landform assemblages, including eskers, deltas, meltwater channels and aligned lineation systems. Because these features were formed or significantly...

Beschreibung: Research Articles Ian Hawes, Karl Safi, Brian Sorrell, Jenny Webster-Brown, David Arscott, Antarctic Science , Volume 23 Issue 03 , pp 235-242 Abstract

Beschreibung: Research Articles G.C. Grobler, A.D.S. Bastos, C.T. Chimimba, S.L. Chown, Antarctic Science , Volume 23 Issue 03 , pp 225-234 Abstract

Beschreibung: The Mt Cer Pluton, Serbia, is a complex laccolith-like intrusion (~ 60 km2), situated along the junction between the southern Pannonian Basin and northern Dinarides. It intrudes Palaeozoic metamorphic rocks causing weak to strong thermal effects. Based on modal and chemical compositions, four rock-types can be distinguished: (1) metaluminous I-type quartz monzonite/quartz monzodiorite (QMZD); (2) peraluminous S-type two-mica granite (TMG), which intrudes QMZD; (3) Stra[z]anica granodiorite/quartz monzonite (GDS); and (4) isolated mafic enclaves (ME), found only in QMZD. 40K-39Ar dating and geological constraints indicate that the main quartz monzonite/quartz monzodiorite body of Mt Cer was emplaced not later than 21 Ma, whereas the emplacement ages of the Stra[z]anica granodiorite/quartz monzonite and two-mica granites are estimated at around 18 and 16 Ma, respectively. The Mt Cer pluton is similar to the Mt Bukulja pluton, some 80 km southwestwards. Genesis of QMZD cannot be interpreted by fractional crystallization coupled with mixing or assimilation. It is best explained by a convection-diffusion process between mantle-derived minette/leucominette magmas and GDS-like magmas followed by two end-member magma mixing. The composition of GDS rocks suggests that GDS-like magmas could have formed by melting of lower crustal lithologies similar to amphibolite/metabasalts. The geochemistry of TMG is reproduced by an Assimilation/Fractional Crystallization model with a ratio of rate of assimilation to rate of fractional crystallization of 0.4, using the compositions of the least evolved TMG of the Bukulja pluton and adjacent metamorphic rocks as proxies for the parental magma and contaminant, respectively. The origin and evolution of the Mt Cer and adjacent Mt Bukulja plutons provide new constraints on the Tertiary geodynamics of the northern Dinarides-southern Pannonian region. The quartz monzonite/quartz monzodiorite is interpreted as a result of the Oligocene post-collisional Dinaride orogen-collapse, which included a limited lithosphere delamination, small-scale mantle upwelling, and melting of the lower crust. By contrast, the two-mica granite magmas formed through melting in shallower crustal levels during the extensional collapse in the Pannonian area.

Beschreibung: Late Carboniferous red-beds, 〈 700 m thick, at outcrop and in the subsurface of the Canonbie Coalfield can be assigned to the Warwickshire Group. They are preserved within the axial part of the Solway Syncline and are divisible into the Eskbank Wood, Canonbie Bridge Sandstone and Becklees Sandstone formations. Sedimentation largely took place on a well-drained alluvial plain, characterized mainly by early, primary oxidation of the strata. Large, northerly-flowing braided river systems were common, with overbank and floodplain fines deposited lateral to the channels; soils formed during intervals of low sediment aggradation. The Canonbie succession includes some of the youngest Carboniferous rocks preserved in the UK. Correlation of the Eskbank Wood Formation is equivocal, but using petrographical, heavy mineral, zircon age dating and palaeocurrent data, the Canonbie Bridge Sandstone Formation can be unambiguously correlated with the Halesowen Formation of Warwickshire, the Pennant Sandstone Formation of South Wales and the offshore Boulton Formation. This suggests that southerly-derived detritus travelled considerable distances from the Variscan highlands of Brittany and/or central Germany across the southern North Sea and UK areas, to a position some hundreds of kilometres north of that previously recognized. The Becklees Sandstone Formation has much in common with the Salop Formation of the English Midlands. It appears to have no preserved equivalent elsewhere in the UK or in the UK sector of the southern North Sea but resembles stratigraphically higher parts of the southern North Sea succession seen in the Dutch sector.

Beschreibung: The morphology and structure of the 1999 lava flows at Mount Cameroon volcano are documented and discussed in relation to local and source dynamics. Structures are analysed qualitatively and more detailed arguments are developed on the processes of levee formation and systematic links between flow dynamics and levee-channel interface geometry. The flows have clear channels bordered by four main types of levees: initial, accretionary, rubble and overflow levees. Thermally immature pahoehoe lava units with overflow drapes define the proximal zone, whereas rubble and accretionary levees are common in the distal region bordering thermally mature aa clinker or blocky aa flow channels. Pressure ridges, squeeze-ups and pahoehoe ropes are the prevalent compressive structures. Standlines displayed on clinkery breccias are interpreted to represent levee-channel interactions in response to changing flow levels. These data complement previous knowledge on lava flow morphology, thus far dominated by Etnean and Hawaiian examples.

Beschreibung: The Takab complex is composed of a variety of metamorphic rocks including amphibolites, metapelites, mafic granulites, migmatites and meta-ultramafics, which are intruded by the granitoid. The granitoid magmatic activity occurred in relation to the subduction of the Neo-Tethys oceanic crust beneath the Iranian crust during Tertiary times. The granitoids are mainly granodiorite, quartz monzodiorite, monzonite and quartz diorite. Chemically, the magmatic rocks are characterized by ASI

Beschreibung: Tectonothermal analysis of a mainly carbonate unit located in the external part of the Variscan orogen in NW Spain is dealt with using the conodont colour alteration index (CAI) and the study of textures of these microfossils. The Kubler index of the illite (KI) is used as a complementary method. The area is characterized by a great uniformity in the CAI values, which in most cases are

Beschreibung: The hot emplacement of the Ronda peridotites (Betic Cordilleras) developed a dynamothermal aureole and partial melts that led to the intrusion of granite dykes in the peridotites. Previous geochronological data place rather broad limits for this event between 22 and 19 Ma. Analyses of neocrystalline zircon rims from large zircon populations yield a U-Pb SHRIMP age of 22.3{+/-}0.7 Ma for the dynamothermal aureole formation, and intrusion ages of granite dykes between 22.6{+/-}1.8 and 21.5{+/-}3.8 support that conclusion. Therefore, these new ages provide a more robust constraint on the hot emplacement of the Ronda peridotites at middle crustal levels.

Beschreibung: The Pele La Group in the Wachi La section in the Black Mountains of central Bhutan represents the easternmost exposure of Cambrian strata known in the Himalaya. The group contains a succession of siliciclastic rocks with minor amounts of carbonate, the uppermost unit of which, the Quartzite Formation, bears age-diagnostic trilobite body fossils that are approximately 493 Ma old. Trilobite species include Kaolishania granulosa, Taipaikia glabra and the new species Lingyuanaspis sangae. A billingsellid brachiopod, Billingsella cf. tonkiniana, is co-occurrent. This fauna is precisely correlated with that of a specific stratigraphic horizon within the upper part of the Kaolishania Zone, Stage 9 of the Cambrian System, Furongian Epoch of the North China block, and thus represents the youngest Cambrian sedimentary rocks yet known from the Himalaya. The faunal similarity suggests proximity between North China and the Himalayan margin at this time. This unit was deposited in a predominantly storm-influenced shelf and shoreface environment. U-Pb geochronological data from detrital zircon grains from the fossil-bearing beds of the Quartzite Formation and strata of the underlying Deshichiling Formation show grain age spectra consistent with those from Cambrian rocks of the Lesser and Tethyan Himalaya in Tibet, India and Pakistan. These data support continuity of the northern Gondwanan margin across the Himalaya. Prominent peaks of approximately 500 Ma zircons in both the Quartzite and Deshichiling formations are consistent with the Furongian (late Cambrian) age assignment for these strata. The presence of these relatively young zircon populations implies rapid post-cooling erosion of igneous bodies and subsequent deposition which may reflect the influence of a widespread Cambro-Ordovician orogenic event evident in the western Himalaya.

Beschreibung: The Miocene-Quaternary Trans-Mexican Volcanic arc is thought to have grown southwards (i.e. trenchward) since the Pliocene. This theory is mainly supported by roughly N-S-directed polygenetic volcanic ranges along which volcanic activity migrates southwards with time. We investigated the eruptive history of one of these ranges, the Sierra Nevada (east boundary of Mexico City basin), by compiling literature ages and providing new K-Ar dates. Our K-Ar ages are the first ones for the northernmost Tlaloc and Telapon volcanoes and for the ancestral Popocatepetl (Nexpayantla). The obtained ages reveal that the four stratovolcanoes forming the range worked contemporaneously during most of the Middle to Late Pleistocene. However, taking into account the onset of the volcanic activity, a southward migration is evidenced along the Sierra Nevada: volcanism initiated at its northern tip at least 1.8 Ma ago at Tlaloc volcano, extended southwards 1 Ma ago with Iztaccihuatl and appeared at its southern end 329 ka ago with the Nexpayantla cone. Such a migration would be most probably primarily driven by Cocos slab roll-back and steepening rather than by regional crustal tectonics, which played a secondary role by controlling the apparent alignment of the volcanoes.

Beschreibung: Electron microprobe analyses of 128 detrital rutile grains from two Jurassic sandstone samples (Hettangian and Bajocian-Bathonian in age) from hydrocarbon exploration wells on the Norwegian margin confirm that more than 85 % of the rutiles were derived from metapelitic rocks. Zr-in-rutile geothermometry confirms that about 83 % of the rutile was formed under high-grade metamorphism (〉750 {degrees}C). Sixty-two rutile grains, including 60 of the identified high-temperature rutile population, were also analysed for U-Pb geochronology using SHRIMP. The 206Pb-238U rutile ages range from approximately 485-292 Ma, with a major cluster between 450 and 380 Ma. These data suggest that the detrital rutile was predominantly derived from a felsic source that experienced granulite-facies metamorphism about 450-380 Ma ago. This conclusion is consistent with derivation from high-grade Caledonian metasedimentary rocks, probably the Krummedal sequence in central East Greenland, as previously suggested by an earlier provenance study using conventional heavy mineral analysis, garnet geochemistry and detrital zircon age dating. The present study underscores the importance of rutile geochemistry and geochronology in quantitative single-mineral provenance analysis of clastic sedimentary rocks.

Beschreibung: Publication year: 2011 Source: Quaternary Research, In Press, Corrected Proof, Available online 18 May 2011 Oliver A.C., Atkinson , David S.G., Thomas , Andrew S., Goudie , Richard M., Bailey The northeastern sector of the Rub' al-Khali desert in the eastern United Arab Emirates (UAE) is dominated by large NE–SW trending dune ridges orientated perpendicular to the currently prevailing northwesterly wind regime. In this study, extensive use has been made of artificially exposed sections through these major dune ridges that reveal internal sedimentary structures and allow an intensive, high-resolution sampling programme to be carried out. Here, we present the optical dating results for samples from 7 sections. The results indicate that dune activity and preservation occurred within the periods 7–3ka, 16–10ka and 22–20ka with evidence of earlier preservation during marine...

Beschreibung: Editorial R.I. Lewis Smith, Antarctic Science , Volume 23 Issue 02 , pp 105-105 Abstract

Beschreibung: Research Articles Jill P. Zamzow, Craig F. Aumack, Charles D. Amsler, James B. McClintock, Margaret O. Amsler, Bill J. Baker, Antarctic Science , Volume 23 Issue 02 , pp 107-116 Abstract

Beschreibung: Research Articles Kevin Hall, Ian Meiklejohn, Adam Bumby, Antarctic Science , Volume 23 Issue 02 , pp 155-163 Abstract

Beschreibung: Research Articles Eva E.R. Philipp, Gunnar Husmann, Doris Abele, Antarctic Science , Volume 23 Issue 02 , pp 127-138 Abstract

Beschreibung: Research Articles Andreas Borchers, Ines Voigt, Gerhard Kuhn, Bernhard Diekmann, Antarctic Science , Volume 23 Issue 02 , pp 164-179 Abstract

Beschreibung: Rapid Communication Maria Olech, Katarzyna J. Chwedorzewska, Antarctic Science , Volume 23 Issue 02 , pp 153-154 Abstract

Beschreibung: Research Articles Giancarlo Lauriano, Caterina Maria Fortuna, Marino Vacchi, Antarctic Science , Volume 23 Issue 02 , pp 139-143 Abstract

Beschreibung: Research Articles D. Pirrie, H.A. Jonkers, J.L. Smellie, J.A. Crame, J.M. McArthur, Antarctic Science , Volume 23 Issue 02 , pp 180-187 Abstract

Beschreibung: Research Articles Jean-Baptiste Thiebot, Amélie Lescroël, David Pinaud, Philip N. Trathan, Charles-André Bost, Antarctic Science , Volume 23 Issue 02 , pp 117-126 Abstract

Beschreibung: Research Articles Stefano Schiaparelli, Maria Chiara Alvaro, Ruth Barnich, Antarctic Science , Volume 23 Issue 02 , pp 144-151 Abstract

Beschreibung: Research Articles Benjamin Bomfleur, Christian Pott, Hans Kerp, Antarctic Science , Volume 23 Issue 02 , pp 188-208 Abstract

Beschreibung: Publication year: 2011 Source: Quaternary Research, In Press, Corrected Proof, Available online 22 February 2011 G., Benito , V.R., Thorndycraft , M.T., Rico , Y., Sánchez-Moya , A., Sopeña , ... A long-term flood record from the Buffels River, the largest ephemeral river of NW South Africa (9250 km2), was reconstructed based on interpretation of palaeoflood, documentary and instrumental rainfall data. Palaeoflood data were obtained at three study reaches, with preserved sedimentary evidence indicating at least 25 large floods during the last 700yr. Geochronological control for the palaeoflood record was provided by radiocarbon and optically stimulated luminescence (OSL) dating. Annual resolution was obtained since the 19th century using the overlapping documentary and instrumental records. Large floods coincided in the past within three main hydroclimatic settings: (1) periods of regular large flood...

Beschreibung: Publication year: 2011 Source: Quaternary Research, In Press, Corrected Proof, Available online 22 February 2011 J. Sakari, Salonen , Heikki, Seppä , Minna, Väliranta , Vivienne J., Jones , Angela, Self , ... To investigate the Holocene climate and treeline dynamics in the European Russian Arctic, we analysed sediment pollen, conifer stomata, and plant macrofossils from Lake Kharinei, a tundra lake near the treeline in the Pechora area. We present quantitative summer temperature reconstructions from Lake Kharinei and Lake Tumbulovaty, a previously studied lake in the same region, using a pollen–climate transfer function based on a new calibration set from northern European Russia. Our records suggest that the early-Holocene summer temperatures from 11,500calyr BP onwards were already slightly higher than at present, followed by a stable Holocene Thermal Maximum (HTM) at 8000–3500calyr BP...

Beschreibung: Publication year: 2011 Source: Quaternary Research, In Press, Corrected Proof, Available online 22 February 2011 Bernard, Hallet , Land L., Washburn , Nuna L., MacDonald , Carl S., Benson , Minze, Stuiver

Beschreibung: Publication year: 2011 Source: Quaternary Research, In Press, Corrected Proof, Available online 3 August 2011 Olaf, Juschus , Maksim, Pavlov , Georg, Schwamborn , Frank, Preusser , Grigory, Fedorov , ... Lake El'gygytgyn is situated in a 3.6Ma old impact crater in northeastern Siberia. Presented here is a reconstruction of the Quaternary lake-level history as derived from sediment cores from the southern lake shelf. There, a cliff-like bench 10m below the modern water level has been investigated. Deep-water sediments on the shelf indicate high lake levels during a warm Mid-Pleistocene period. One period with low lake level prior to Marine Oxygen Isotope Stage (MIS) 3 has been identified, followed by a period of high lake level (10m above present). In the course of MIS 2 the lake level dropped to −10m....

Beschreibung: Publication year: 2011 Source: Quaternary Research, In Press, Corrected Proof, Available online 1 June 2011 Claire A., Kaufman , Scott F., Lamoureux , Darrell S., Kaufman Sedimentological analyses of 289years (AD 1718–2006) of varved sediment from Shadow Bay, southwest Alaska, were used to investigate hydroclimate variability during and prior to the instrumental period. Varve thicknesses relate most strongly to total annual discharge (r2=0.75, n=43, p

Beschreibung: Publication year: 2011 Source: Quaternary Research, In Press, Corrected Proof, Available online 26 May 2011 David K., Wright , Steven L., Forman , Michael R., Waters , John C., Ravesloot Eolian sediments are common within the middle Gila River Valley, southern Arizona, and reflect variability in eolian and fluvial processes during the late Holocene. This study focuses on deciphering the stratigraphic record of eolian deposition and associated luminescence dating of quartz extracts by single aliquot regeneration (SAR) protocols. Stratigraphic assessment coupled with luminescence ages indicates that there are four broad eolian depositional events at ca. 3145±220yr, 1950–1360yr, 800±100yr, and 690–315yr. This nascent chronology, correlated with regional archeological evidence and paleoclimate proxy datasets, leads to two general conclusions: (1) loess deposits, transverse-dune formation and sand-sheet deposition in the late Holocene are...

Beschreibung: Research Articles P.J.A. Pugh, R.I. Lewis Smith, Antarctic Science , Volume 23 Issue 05 , pp 442-448 Abstract

Beschreibung: Book Reviews William Block, Antarctic Science , Volume 23 Issue 05 , pp 500-500 Abstract

Beschreibung: Research Articles Marijke Ooms, Bart van de Vijver, Stijn Temmerman, Louis Beyens, Antarctic Science , Volume 23 Issue 05 , pp 431-441 Abstract

Beschreibung: Research Articles T.C. Hawes, Antarctic Science , Volume 23 Issue 05 , pp 456-460 Abstract

Beschreibung: Rapid Communication Stacy Z. Kim, David G. Ainley, Jean Pennycook, Joseph T. Eastman, Antarctic Science , Volume 23 Issue 05 , pp 469-470 Abstract

Beschreibung: Book Reviews D.W.H. Walton, Antarctic Science , Volume 23 Issue 05 , pp 499-499 Abstract

Beschreibung: Research Articles Christophe Barbraud, Maria Gavrilo, Yuri Mizin, Henri Weimerskirch, Antarctic Science , Volume 23 Issue 05 , pp 461-468 Abstract

Beschreibung: Editorial Daniela N. Schmidt, Andy Ridgwell, Antarctic Science , Volume 23 Issue 05 , pp 417-417 Abstract

Beschreibung: Research Articles Werner Ehrmann, Claus-Dieter Hillenbrand, James A. Smith, Alastair G.C. Graham, Gerhard Kuhn, Robert D. Larter, Antarctic Science , Volume 23 Issue 05 , pp 471-486 Abstract

Beschreibung: Review Articles Susanne Becker, María Liliana Quartino, Gabriela Laura Campana, Philip Bucolo, Christian Wiencke, Kai Bischof, Antarctic Science , Volume 23 Issue 05 , pp 419-430 Abstract

Beschreibung: Research Articles Peter Rehm, Rachel A. Hooke, Sven Thatje, Antarctic Science , Volume 23 Issue 05 , pp 449-455 Abstract

Beschreibung: Publication year: 2011 Source: Quaternary Research, Available online 5 December 2011 Sarah J. Ivory, Anne-Marie Lézine, Annie Vincens, Andrew S. Cohen Fossil pollen analyses from northern Lake Malawi, southeast Africa, provide a high-resolution record of vegetation change during the Pleistocene/Holocene transition (~ 18–9 ka). Recent studies of local vegetation from lowland sites have reported contrasting rainfall signals during the Younger Dryas (YD). The Lake Malawi record tracks regional vegetation changes and allows comparison with other tropical African records identifying vegetation opening and local forest maintenance during the YD. Our record shows a gradual decline of afromontane vegetation at 18 ka. Around 14.5 ka, tropical seasonal forest and Zambezian miombo woodland became established. At ~ 13 ka, drier, more open formations gradually became prevalent. Although tropical seasonal forest taxa were still present in the watershed during the YD, this drought-intolerant forest type was likely restricted to areas of favorable edaphic conditions along permanent waterways. The establishment of drought-tolerant vegetation followed the reinforcement of southeasterly tradewinds resulting in a more pronounced dry winter season after ~ 11.8 ka. The onset of the driest, most open vegetation type was coincident with a lake low stand at the beginning of the Holocene. This study demonstrates the importance of global climate forcing and local geomorphological conditions in controlling vegetation distribution.

Beschreibung: Publication year: 2011 Source: Quaternary Research, Available online 2 December 2011 Torben C. Rick, Gregory A. Henkes, Darrin L. Lowery, Steven M. Colman, Brendan J. Culleton Radiocarbon dates from known age, pre-bomb eastern oyster (Crassostrea virginica) shells provide local marine reservoir corrections (∆R) for Chesapeake Bay and the Middle Atlantic coastal area of eastern North America. These data suggest subregional variability in ∆R, ranging from 148 ± 46C yr on the Potomac River to − 109 ± 38C yr at Swan Point, Maryland. The ∆Rweighted mean for the Chesapeake's Western Shore (129 ± 22C yr) is substantially higher than the Eastern Shore (− 88 ± 23C yr), with outer Atlantic Coast samples falling between these values (106 ± 46 and 2 ± 46C yr). These differences may result from a combination of factors, includingC-depleted freshwater that enters the bay from some if its drainages,C-depleted seawater that enters the bay at its mouth, and/or biological carbon recycling. We advocate using different subregional ∆Rcorrections when calibratingC dates on aquatic specimens from the Chesapeake Bay and coastal Middle Atlantic region of North America.

Beschreibung: Publication year: 2011 Source: Quaternary Research, Available online 3 December 2011 Charline Giguet-Covex, Fabien Arnaud, Dirk Enters, Jérôme Poulenard, Laurent Millet, ... In central Western Europe, several studies have shown that colder Holocene periods, such as the Little Ice Age, also correspond to wet periods. However, in mountain areas which are highly sensitive to erosion processes and where precipitation events can be localized, past evolution of hydrological activity might be more complicated. To assess these past hydrological changes, a paleolimnological approach was applied on a 13.4-m-long sediment core taken in alpine Lake Anterne (2063 m asl) and representing the last 3.5 ka. Lake sedimentation is mainly composed of flood deposits triggered by precipitation events. Sedimentological and geochemical analyses show that floods were more frequent during cold periods while high-intensity flood events occurred preferentially during warmer periods. In mild temperature conditions, both flood patterns are present. This underlines the complex relationship between flood hazards and climatic change in mountain areas. During the warmer and/or dryer times of the end of Iron Age and the Roman Period, both the frequency and intensity of floods increased. This is interpreted as an effect of human-induced clearing for grazing activities and reveals that anthropogenic interferences must be taken into account when reconstructing climatic signals from natural archives.

Beschreibung: Publication year: 2011 Source: Quaternary Research, Available online 3 December 2011 Stephen A. Hall, William L. Penner, Manuel R. Palacios-Fest, Artie L. Metcalf, Susan J. Smith A thick alluvial sequence in central New Mexico contains the Scholle wet meadow deposit that traces upstream to a paleospring. The wet meadow sediments contain an abundant fauna of twenty-one species of freshwater and terrestrial mollusks and ten species of ostracodes. The mollusks and ostracodes are indicative of a local high alluvial water table with spring-supported perennial flow but without standing water. Pollen analysis documents shrub grassland vegetation with sedges, willow, and alder in a riparian community. Stable carbon isotopes from the wet meadow sediments have δC values ranging from − 22.8 to − 23.3‰, indicating that 80% of the organic carbon in the sediment is derived from C3species. The wet meadow deposit is AMS dated 10,400 to 9700 C yr BP, corresponding to 12,300 to 11,100 cal yr BP and overlapping in time with the Younger Dryas event (YD). The wet meadow became active about 500 yr after the beginning of the YD and persisted 400 yr after the YD ended. The Scholle wet meadow is the only record of perennial flow and high water table conditions in the Abo Arroyo drainage basin during the past 13 ka.

Beschreibung: Publication year: 2011 Source: Quaternary Research, Available online 3 December 2011 Antonio B. Rodriguez, Matthew N. Waters, Michael F. Piehler Carolina bays are nearly ubiquitous along ~ 1300 km of the North American Atlantic Coastal Plain, but relatively few bays have been examined in detail, making their formation and evolution a topic of controversy. The Lake Mattamuskeet basin, eastern North Carolina, USA, is a conglomeration of multiple Carolina bays that form a 〉 162 kmlake. The eastern shoreline of the lake is made up of a 2.9-km-wide plain of parabolic ridges that recorded rapid shoreface progradation. The lower shoreface deposit contains abundant charcoal beds and laminae dated 6465–6863 cal yr BP, corresponding with initiation of a lacustrine environment in the eastern part of the lake. A core from the western part of the lake sampled a 1541–1633 cal yr BP charcoal bed at the base of the lacustrine unit, indicating formation of this part of the basin postdates the eastern basin. Lake Mattamuskeet has no relationship to the Younger Dryas or a linked impact event because rim accretion significantly postdates 12,000 cal yr BP. The shoreline progradation, and association of charcoal beds with the oldest lake sediment in both main parts of the basin, suggest that fire and subsequent hydrodynamic processes were associated with initial formation of these Carolina bays.

Beschreibung: Publication year: 2012 Source: Quaternary Research R. Jayangondaperumal, M.K. Murari, P. Sivasubramanian, N. Chandrasekar, A.K. Singhvi The Holocene and late Pleistocene environmental history of the teri (‘sandy waste’ in local parlance) red sands in the southeast coastal Tamil Nadu was examined using remote sensing, stratigraphy, and optically stimulated luminescence (OSL) dating. Geomorphological surveys enabled the classification of the teri red sands as, 1) inland fluvial teri, 2) coastal teri and, 3) near-coastal teri dunes. The inland teri sediments have higher clay and silty-sand component than the coastal and near-coastal teri, suggesting that these sediments were deposited by the fluvial process during a stronger winter monsoon around 〉 15 ka. The coastal teri dunes were deposited prior to 11.4 ± 0.9 ka, and the near-coastal dunes aggraded at around 5.6 ± 0.4 ka. We interpret that the coastal dunes were formed during a period of lower relative sea level and the near-coastal dunes formed during a period of higher sea level. Dune reddening is post deposition occurred after 11.4 ± 0.9 ka for the coastal teri dunes and after 5.6 ± 0.4 ka for the near-coastal teri dunes. Presence of microlithic sites associated with the coastal dunes suggest that the cultures existed in the region during 11.4 ± 0.9 ka and 5.6 ± 0.4 ka.

Beschreibung: Publication year: 2012 Source: Quaternary Research Bradley E. Blumer, Alan F. Arbogast, Steven L. Forman Extensive coastal dunes occur in the Great Lakes region of North America, including northwestern Michigan where some are perched on high (~ 100 m) bluffs. This study focuses on such a system at Arcadia Dunes and is the first to systematically generate optical ages from stratigraphic sections containing buried soils. Dune growth began ca. 4.5 ka during the Nipissing high lake stand and continued episodically thereafter, with periods of increased sand supply at ca. 3.5 ka and ca. 1.7 ka. The most volumetrically dominant phase of dune growth began ca. 1.0 ka and continued intermittently for about 500 years. It may have begun due to the combined effects of a high lake phase, potential changes in lake hydrodynamics with final isostatic separation of Lake Superior from Lakes Michigan and Huron, and increased drought and hydrologic variability associated with the Medieval Warm Period. Thus, this latest eolian phase likely reflects multiple processes associated with Great Lakes water level and climate variability that may also explain older eolian depositional events. Comparison of Arcadia ages and calendar corrected 14 C ages from previous studies indicate broad chronological agreement between events at all sites, although it appears that dune growth began later at Arcadia.

Beschreibung: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 2 Miguel Cortés Sánchez, Francisco J. Jiménez Espejo, María D. Simón Vallejo, Juan F. Gibaja Bao, António Faustino Carvalho, Francisca Martinez-Ruiz, Marta Rodrigo Gamiz, José-Abel Flores, Adina Paytan, José A. López Sáez, Leonor Peña-Chocarro, José S. Carrión, Arturo Morales Muñiz, Eufrasia Roselló Izquierdo, José A. Riquelme Cantal, Rebecca M. Dean, Emília Salgueiro, Rafael M. Martínez Sánchez, Juan J. De la Rubia de Gracia, María C. Lozano Francisco, José L. Vera Peláez, Laura Llorente Rodríguez, Nuno F. Bicho New data and a review of historiographic information from Neolithic sites of the Malaga and Algarve coasts (southern Iberian Peninsula) and from the Maghreb (North Africa) reveal the existence of a Neolithic settlement at least from 7.5 cal ka BP. The agricultural and pastoralist food producing economy of that population rapidly replaced the coastal economies of the Mesolithic populations. The timing of this population and economic turnover coincided with major changes in the continental and marine ecosystems, including upwelling intensity, sea-level changes and increased aridity in the Sahara and along the Iberian coast. These changes likely impacted the subsistence strategies of the Mesolithic populations along the Iberian seascapes and resulted in abandonments manifested as sedimentary hiatuses in some areas during the Mesolithic–Neolithic transition. The rapid expansion and area of dispersal of the early Neolithic traits suggest the use of marine technology. Different evidences for a Maghrebian origin for the first colonists have been summarized. The recognition of an early North-African Neolithic influence in Southern Iberia and the Maghreb is vital for understanding the appearance and development of the Neolithic in Western Europe. Our review suggests links between climate change, resource allocation, and population turnover.

Beschreibung: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 2 Ignacio A. Jara, Patricio I. Moreno We present detailed pollen and charcoal records from Lago Pichilafquén (~ 41°S) to decipher the effects of climate change and varying disturbance regimes on the composition and structure of the vegetation on the Andean foothills of northwestern Patagonia during the last 2600 yr. Here, temperate rainforests have dominated the landscape since 2600 cal yr BP with variations ranging from cool-temperate and wet north Patagonian rainforests to relatively warm and summer-drought-resistant Valdivian rainforests. We interpret relatively warm/dry conditions between 1900–2600, 690–750 and 320–430 cal yr BP, alternating with cold/wet conditions between 1500–1900, 750–1100 and 430–690 cal yr BP. Rapid deforestation and spread of plants introduced by Europeans occurred at 320 and 140 cal yr BP. The record includes five tephras with ages of 2130, 1460, 1310, 1210, and 340 cal yr BP, all of which precede local fire events and increases in trees favored by disturbance by less than 100 yr. We conclude that centennial-scale changes in the southern westerlies were the primary driver of vegetation shifts in northwestern Patagonia over the last 2600 yr. Within this interval, local disturbance regimes altered the structure, composition, and dynamics of the lowland rainforest vegetation during several discrete, short-lived episodes.

Beschreibung: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 2 Warren W. Wood, Richard M. Bailey, Brian A. Hampton, Thomas F. Kraemer, Zhong Lu, David W. Clark, Rhodri H.R. James, Khalid Al Ramadan The coastline along the southern Arabian Gulf between Al Jubail, Kingdom of Saudi Arabia, and Dubai, UAE, appears to have risen at least 125 m in the last 18,000 years. Dating and topographic surveying of paleo-dunes (43–53 ka), paleo-marine terraces (17–30 ka), and paleo-marine shorelines (3.3–5.5 ka) document a rapid, 〉 1 mm/a subsidence, followed by a 6 mm/a uplift that is decreasing with time. The mechanism causing this movement remains elusive but may be related to the translation of the coastal area through the backbasin to forebulge hinge line movement of the Arabian plate or, alternatively, by movement of the underlying Infracambrian-age Hormuz salt in response to sea-level changes associated with continental glaciation. Independent of the mechanism, rapid and episodic uplift may impact the design of engineering projects such as nuclear power plants, airports, and artificial islands as well as the interpretation of sedimentation and archeology of the area.

Beschreibung: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 2 Ryszard K. Borówka, Wacław Strobel, Stanisław Hałas The environmental conditions of the Szczecin Bay, which existed prior to Szczecin Lagoon, have been reconstructed on the basis of the stable carbon and oxygen isotope ( 18 O and 13 C) analysis and radiocarbon dates obtained for subfossil shells of Cerastoderma (Cardium) glaucum . The shells in the collected core were well preserved in their life positions, representing a geochemical record of past temperature variation over the middle Holocene. Three major periods with different thermal conditions have been distinguished in the interval ~ 6000–4300 cal yr BP, when the important Littorina regional transgression took place. During the first period, 6000–5250 cal yr BP, water temperature decreased by 1.4°C, and then remained constant over the second period (5250–4750 cal yr BP). In contrast, during the third period (4750–4300 cal yr BP) both δ-values were highly variable and the mean summer temperature (March–November) increased by about 3.5°C. During first two periods, δ 18 O and δ 13 C were significantly correlated, indicating stability of the environmental conditions.

Beschreibung: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 2 Georg Irion, Jáder Onofre de Morais, Friederike Bungenstock Beach-rock exposures provide a record of Holocene sea-level rise along the 560-km-long northeast-facing coast of Ceará, Brazil, that differs from the record available along the other 4300 km of Brazilian coastline further south. Whereas documentation is available from southern Brazil to show Holocene sea levels as much as 5 m above today's level, our observations along the northeastern coast indicate that sea level here was not above the present-day level during the Holocene. Near Jericoacoara, about 240 km northwest of Fortaleza, characterized by strong surf, Precambrian rocks crop out from under a temporary cover of sand in small protected locations with less surf. Here in this upper tidal zone beach rock is being formed, while it is being dismembered synchronously by erosion at lower tide levels. This shows a rising sea level. Along the entire coast of Ceará west of Ponta Grossa the absence of beach rock higher than spring tide level indicates that sea-level was not above its present-day level during the Holocene. Notches in bedrock situated between 2 m and 6 m above spring-tide high-water level that we formerly described as Holocene, are now believed to be Sangamonian.

Beschreibung: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 2 Roland Zech Surface exposure dating has become a helpful tool for establishing numeric glacial chronologies, particularly in arid high-mountain regions where radiocarbon dating is challenging due to limited availability of organic material. This study presents 13 new 10 Be surface exposure ages from the Kitschi-Kurumdu Valley in the At Bashi Range, Tien Shan. Three moraines were dated to ~ 15, 21 and 〉 56 ka, respectively, and corroborate previous findings that glacial extents in the Tien Shan during Marine Oxygen Isotope Stage (MIS) 2 were limited compared to MIS 4. This likely documents increasingly arid conditions in Central Asia during the last glacial cycle. Morphological evidence in the Kitschi-Kurumdu Valley and a detailed review of existing numeric glacial chronologies from the Tien Shan indicate that remnants of the penultimate glaciation (MIS 6) are preserved, whereas evidence for MIS 5 glacier advances remains equivocal. Reviewed and recalculated exposure ages from the Pamir mountains, on the other hand, reveal extensive MIS 5 glacial extents that may indicate increased monsoonal precipitation. The preservation of MIS 3 moraines in the Tien Shan and the southern Pamir does not require any monsoonal influence and can be explained alternatively with increased precipitation via the westerlies.

Beschreibung: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 2 Antonio González-Ramón, Bartolomé Andreo, Antonio Ruiz-Bustos, David A. Richards, José Antonio López-Sáez, Francisca Alba-Sánchez Cucú cave is a small cavity, 1600 m above sea level on the southern slope of Sierra de María (Almería Province, SE Spain), where current mean annual precipitation is 〈 450 mm. Fossils and palynomorphs contained within a sedimentary sequence, up to 9 m in depth, allow us to consider the prevailing climatic conditions, and the timing of cavern development. The lithological sequence is dominated by clast-supported detrital material with no evidence of alluvial transport. These sediments were formed by freeze-cracking during periglacial conditions, causing further cave enlargement after initial solutional development. The clastic sequence formed during cold climates is covered by a flowstone that was deposited during a period of warmer, wetter conditions. This provides a minimum U–Th isochron age of 40.2 ± 4.5 ka for the timing of periglacial action. Micromammal fossil species indicate a chronology between 140 and 80 ka. Paleoecological data based on the structure of the mammal community indicates that cold conditions prevailed at the time of deposit. In the studied sequence the presence of anthropogenic components has not been documented. The pollen assemblages identified are a common feature of Pleistocene cold stages that are in semi-arid regions.

Beschreibung: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 2 Aya Schneider Mor, Ruth Yam, Cristina Bianchi, Martina Kunz-Pirrung, Rainer Gersonde, Aldo Shemesh The relationships among internally consistent records of summer sea-surface temperature (SSST), winter sea ice (WSI), and diatomaceous stable isotopes were studied across seven terminations over the last 660 ka in sedimentary cores from ODP sites 1093 and 1094. The sequence of events at both sites indicates that SSST and WSI changes led the carbon and nitrogen isotopic changes in three Terminations (TI, TII and TVI) and followed them in the other four Terminations (TIII, TIV, TV and TVII). In both TIII and TIV, the leads and lags between the proxies were related to weak glacial mode, while in TV and TVII they were due to the influence of the mid-Pleistocene transition. We show that the sequence of events is not unique and does not follow the same pattern across terminations, implying that the processes that initiated climate change in the Southern Ocean has varied through time.

Beschreibung: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 2 Martina Demuro, Duane G. Froese, Lee J. Arnold, Richard G. Roberts Improved chronological control on the penultimate advance of the Cordilleran Ice Sheet in northwest Canada (the Reid glaciation) is required for a better understanding of late Quaternary palaeoclimatic and palaeoenvironmental change in eastern Beringia. However, reliable dating of glaciation events beyond the last glacial maximum is commonly hindered by a lack of directly dateable material. In this study we (i) provide the first combined minimum and maximum age constraint on the Reid glaciation at Ash Bend, its reference locale in the Stewart River valley, northwestern Canadian Cordillera, using single-grain optically stimulated luminescence dating of quartz; and (ii) compare the timing of the Reid glaciation with other penultimate ice sheet advances in the region with the aim of establishing improved glacial reconstructions in eastern Beringia. We obtain ages of 158 ± 18 ka and 132 ± 18 ka for glaciofluvial sands overlying and underlying the Reid till, respectively. These ages indicate that the Reid advance, at its reference locale, occurred during MIS 6. This precludes an earlier MIS 8 age, and suggests that the Reid advance may have been synchronous with the Delta glaciation of central Alaska, and is likely correlative with the Mirror Creek glaciation in southern Yukon.

Beschreibung: Publication year: 2012 Source: Quaternary Research, Volume 77, Issue 2 Patrick J. Applegate, Nathan M. Urban, Klaus Keller, Thomas V. Lowell, Benjamin J.C. Laabs, Meredith A. Kelly, Richard B. Alley The statistical distributions of cosmogenic nuclide measurements from moraine boulders contain previously unused information on moraine ages, and they help determine whether moraine degradation or inheritance is more important on individual moraines. Here, we present a method for extracting this information by fitting geomorphic process models to observed exposure ages from single moraines. We also apply this method to 94 10 Be apparent exposure ages from 11 moraines reported in four published studies. Our models represent 10 Be accumulation in boulders that are exhumed over time by slope processes (moraine degradation), and the delivery of boulders with preexisting 10 Be inventories to moraines (inheritance). For now, we neglect boulder erosion and snow cover, which are likely second-order processes. Given a highly scattered data set, we establish which model yields the better fit to the data, and estimate the age of the moraine from the better model fit. The process represented by the better-fitting model is probably responsible for most of the scatter among the apparent ages. Our methods should help resolve controversies in exposure dating; we reexamine the conclusions from two published studies based on our model fits.