Latest Quaternary papers

Tuesday, 21 October 2014
Journal of Quaternary Science

Individual glass shard trace element analyses confirm that all known Toba tephra reported from India is from the c. 75-ka Youngest Toba eruption

Uncertainty over the identity and age of Toba tephras across peninsular India persists, with radiometric age dates contradicting earlier compositional data, which have been used to identify this important stratigraphic marker as the Youngest Toba Tuff (YTT). To address this issue, new single glass shard analyses have been performed for samples from Morgaon and Bori (north-western India), which have recently been dated at c. 800 ka. These, and indeed all Toba tephra samples thus far analysed from India, show the presence of four populations of glass shards (defined by their Ba/Y ratio), which uniquely identifies them as products of the c. 75-ka Youngest Toba eruption. Confirmation that the YTT fingerprint is characteristic comes from new analyses of Oldest Toba Tuff (OTT) glass shards from five sites in the Indian Ocean. These are compositionally identical to Layer D from the ODP site 758 sediment core (c. 800 ka), and belong to a single, low-Ba population, clearly different from YTT. These analyses show that there is essentially no reworked OTT material in the YTT eruption, and indicate unequivocally that all known Toba tephra occurrences in India belong to the c. 75-ka Youngest Toba eruption.

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Saturday, 18 October 2014
Boreas

Late Holocene beetle assemblages and environmental change in Gammelhemmet, northern Sweden

Analysis of insect fossil remains retrieved from a bog close to the abandoned farm at Gammelhemmet, near Lycksele in Swedish Lapland, enabled the reconstruction of environmental changes at the site over the last 2500 years. These results represent the first late Holocene palaeoentomological succession studied for insect remains in the Västerbotten interior, and they provide new evidence for landscape change in the area. Around 2000 years ago, at the end of the early Iron Age, disappearance of the tree and leaf litter fauna and an increase in aquatic species indicate the expansion of wetlands in the area. Patches of a multi-aged mixed woodland with a diverse assemblage of forest-dwelling beetles succeeded the wetland ∼1500 years ago, at the beginning of the late Iron Age. A marked change to open and drier conditions, and the presence of species often found in grassland and cultivated ground took place during the post-Medieval period. Our evidence indicates drainage of the area prior to the 18th century, placing the initiation of agricultural activities in Gammelhemmet earlier than the documentary record. Our research shows the potential of the use of fossil insects for understanding environmental change and also human impact on the landscape, even of limited scale, from natural contexts.

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Thursday, 16 October 2014
Boreas

A Holocene sea-level curve and revised isobase map based on isolation basins from near the southern tip of Norway

We report a new Holocene relative sea-level curve based on the stratigraphy in five closely located isolation basins near Lista in southernmost Norway. The results detail the progress and timing of the mid-Holocene Tapes transgression, the peak of which in this region represents the highest postglacial sea level, as well as the rate of land emergence since then. One additional cored basin is situated above the marine limit. All the basins have bedrock sills that were levelled using a differential GPS. Isolation and ingression boundaries were identified by macrofossil analysis and radiocarbon dated on terrestrial plant remains. In most cases several dates were obtained from each transition. Relative sea level rose with a mean rate of 7 mm a−1 during the last part of the Tapes transgression 8600−8200 cal. a BP and then gradually slowed to a mean rate of 1 mm a−1 from 8200−7000 cal. a BP. Mean sea level reached ∼5 m higher than the present level when the transgression culminated. Land emergence took place after this, first slowly at a mean rate of 0.4 mm a−1 until ∼3900 cal. a BP before it increased to 2.6 mm between 3900 and 3400 cal. a BP. Since then it has slowly decreased until today and has been ∼0.2 mm a−1 for the last 2000 years. Based on the new curve we present updated Tapes isobases for the region that are displaced by ∼20 km in relation to the existing model. From one basin we also report a 5–10 cm thick layer of sorted, sandy gravel, embedded in a more than 5-m-thick deposit of homogeneous shallow-marine mud. The gravel was deposited ∼5500 cal. a BP, which is the same age as a tsunami deposit previously mapped in Shetland. As several typical characteristics of tsunami facies deposits are lacking, the origin of the gravel layer remains inconclusive.

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Wednesday, 15 October 2014
Journal of Quaternary Science

Lateglacial cryptotephra detected within clay varves in Östergötland, south-east Sweden

Here we present a 710-year-long floating varve record from south-east Sweden. Tephra analyses confirm the presence of the rhyolitic Vedde Ash preserved within two consecutive varve years, confirming the Younger Dryas age of the varve series. This permits, for the first time, direct correlation of Swedish varved clay with other records of equivalent resolution which also preserve the Vedde Ash and demonstrates that the potential exists to independently date the Swedish Timescale. This discovery will allow direct comparison of rates, timing and duration of key climatic events across Europe and the North Atlantic region in records of equivalent resolution.

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Wednesday, 15 October 2014
Journal of Quaternary Science

Paleoenvironmental implications of two relative indicator rodent taxa during the Pleistocene to Holocene transition in south-eastern Washington state, USA

Local pollen data, diminution of body size of three ungulate species, and decreased mammalian richness and evenness all indicate grass decreased in abundance during the Pleistocene–Holocene transition (PHT) in eastern Washington state, USA. This paleoenvironmental history suggests that the abundance of remains of Microtus sp. should decrease as remains of Peromyscus maniculatus increase in abundance during the PHT. These two taxa have well-known ecologies relative to one another. PHT sediments at the Marmes archeological site in south-eastern Washington state are sorted into three chronologically sequent, isotaphonomic analytical units. Relative abundances of remains of Microtus sp. and P. maniculatus shift across the analytical units in the predicted manner whether raw abundances or rarified abundances are considered. These results suggest relative abundances of remains of Microtus sp. and P. maniculatus recovered from other sites may be used as relative indicators of paleohabitats. Their abundances at Homestead Cave, Utah, shift as predicted from the Late Pleistocene through the Early Holocene.

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Wednesday, 15 October 2014
Journal of Quaternary Science

Using palaeoenvironmental DNA to reconstruct past environments: progress and prospects

Palaeoenvironmental DNA (PalEnDNA) is defined as ancient DNA (aDNA) originating from disseminated genetic material within palaeoenvironmental samples. Sources of PalEnDNA include marine and lake sediments, peat, loess, till, ice, permafrost, palaeosols, coprolites, preserved gut contents, dental calculus, tephras, and soils as well as deposits in caves/rockshelters and at archaeological sites. PalEnDNA analysis provides a relatively new tool for Quaternary and archaeological sciences and its applications have included palaeoenvironmental and palaeodietary reconstructions, testing hypotheses regarding megafaunal extinctions, human–environment interactions, taxonomic studies, and studies of DNA damage. Because PalEnDNA samples comprise markedly different materials, and represent wide-ranging depositional and taphonomic contexts, various issues must be addressed to achieve robust, reproducible findings. Such issues include climatic and temporal limitations, the biological origin and state (free versus bound) of PalEnDNA, stratigraphic reliability, sterile sampling, ability to distinguish modern from aDNA signals, DNA damage and PCR amplification, DNA extraction methods, and taxonomic resolution. In this review, we provide a non-specialist introduction to the use of PalEnDNA for Quaternary and archaeological researchers, assess attributes and limitations of this palaeoenvironmental tool, and discuss future prospects of using PalEnDNA to reconstruct past environments.

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Wednesday, 15 October 2014
Journal of Quaternary Science

Towards a protocol for the trace element analysis of glass from rhyolitic shards in tephra deposits by laser ablation ICP-MS

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is used widely to analyse single volcanic glass shards from Quaternary tephra deposits for stratigraphic correlation. As yet, no generally accepted protocol for these analyses exists and published methods report significant differences in crater size and calibration strategies. Using Ca as the ‘internal standard’ (CaI.S.), and not SiI.S., for the analysis of rhyolitic glass can cause significant problems, because of ablation of (i) Ca-rich phenocrysts, notably ‘ubiquitous’ plagioclase, but also calcic-amphibole, apatite and allanite or (ii) mounting epoxy resin which can contribute to the Ca internal standard signal. Using CaI.S. can cause underreporting of many elements which concentrate in Ca-rich phenocrysts, making their ablation difficult to recognize, but when using SiI.S., no such underreporting occurs. Additionally, larger ablation craters (50 µm diameter) potentially incorporate even small volumes of phenocryst material, whereas smaller craters (<20 µm diameter) more frequently miss phenocrysts. Thus, for the LA-ICP-MS analysis of rhyolitic glass shards, smaller ablation craters should be employed and calibrated using SiI.S., allowing recognition and removal of analyses incorporating Ca-rich phenocrysts and avoiding issues related to the ablation of the mounting resin.

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Wednesday, 15 October 2014
Journal of Quaternary Science

Holocene vegetation history, precipitation changes and Indian Summer Monsoon evolution documented from sediments of Xingyun Lake, south-west China

We present a pollen-based precipitation reconstruction and multi-proxy records from a 485-cm-long sequence from a sediment core from Xingyun Lake, Yunnan Plateau, south-west China, which depicts the evolution of the Indian Summer Monsoon (ISM) during the last 8500 years. Pollen and other palaeoenvironmental records document several stages of vegetation history and climate change. The warmest and wettest climate in the Xingyun Lake catchment occurred before 5500 cal a BP, and subsequently the climate became gradually drier. After 2000 cal a BP the regional environmental conditions became unstable, and a wet Medieval Warm Period is probably recorded. Our reconstruction of the ISM is similar to that portrayed by Holocene speleothem δ18O records from southern China, but is distinctly different from the East Asian Summer Monsoon (EASM) evolution, which features a mid-Holocene maximum. Our results support the hypothesis that the ISM and EASM evolved asynchronously during the Holocene, and imply that the Chinese speleothem δ18O records from southern China may principally reflect changes in moisture source from the Indian monsoon domain, and thus record the history of the ISM rather than the EASM.

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Wednesday, 15 October 2014
Journal of Quaternary Science

Provenance of sediment in the Labrador Current: a record of hinterland glaciation over the past 125 ka

The Labrador Current flows southward along the continental margin off eastern Canada and is the principal source of sediment to the outer continental margin areas where ice sheets did not cross the continental shelf. We present multi-proxy mineralogical and geochemical records based principally on X-ray diffraction and X-ray fluorescence for core 2011031-059 from northern Flemish Cap to determine changes in supply and hence to reconstruct provenance evolution during the last glacial cycle. The calcite to dolomite ratios in Heinrich layers ranged from 2 to 4, suggesting carbonate layers derived from Hudson Strait as early as Marine Isotope Stage (MIS) 5a–d. Mineral abundance shows three time-dependent predominant sediment sources other than in Heinrich layers: (i) Baffin Bay shelves and adjacent land in MIS 5 and 1, with high Ca, Sr, kaolinite and feldspars and low clay minerals and calcite/dolomite ratios; (ii) Labrador in MIS 3, with low clays and grey color; and (iii) north-east Newfoundland Shelf in MIS 2 and 4, with higher concentrations of clay minerals, red sandstones and transition elements. These results allow a reconstruction of principal ice streams supplying the north-west Atlantic over the last full glacial cycle.

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Wednesday, 15 October 2014
Journal of Quaternary Science

The detailed tephrostratigraphy of a core from the south-east Black Sea spanning the last ∼60 ka

One visible volcanic ash layer and 21 non-visible, cryptotephra horizons have been identified in the M72/5-25-GC1 core from the south-east Black Sea that spans the last ∼60 ka. Glass chemistry suggests that the tephras derive from Italian, Hellenic and Turkish sources. The visible tephra layer is trachytic in composition and has been correlated to the ∼39 ka Campanian Ignimbrite super-eruption from Campi Flegrei caldera, Italy. Two cryptotephra layers are associated with eruptions from Acigöl volcano (Turkey) around the Last Glacial Maximum, another is linked to activity at Erciyes Dagi in the Early Holocene (Perikartini or Karagüllü), and a cryptotephra layer near the top of the core correlates to the ∼3.6k cal a BP Minoan (marine Z2) tephra from Santorini (Thera), Greece. This extends the known dispersal area for all these volcanic ash units. Many other calc-alkaline rhyolite layers preserved in the core are likely to be from central Anatolian sources but the lack of detailed proximal data for many of the volcanoes in the region prohibits further correlations. The tephrostratigraphy and glass compositional data presented here allow the tephra layers to be used to correlate sedimentary archives across the region, and help to extend the Mediterranean tephrochronology framework towards the east.

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Wednesday, 15 October 2014
Earth and Planetary Science News

• Arctic sea route path planning based on an uncertain ice prediction model

• Minjoo Choi, Hyun Chung, Hajime Yamaguchi, Keisuke Nagakawa

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Wednesday, 15 October 2014
Earth and Planetary Science News

• Heat-flow regimes and the hydrate stability zone of a transient, thermogenic, fault-controlled hydrate system (woolsey mound northern Gulf of Mexico)

• L. Macelloni, C.B. Lutken, S. Garg, A. Simonetti, M. D’Emidio, R.M. Wilson, K. Sleeper, L.L. Lapham, T. Lewis, M. Pizzi, J.H. Knapp, C.C. Knapp, J. Brooks, T.M. McGee

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Wednesday, 15 October 2014
Earth and Planetary Science News

• High-resolution sequence stratigraphy of clastic shelves III: Applications to reservoir geology

• Massimo Zecchin, Octavian Catuneanu

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Wednesday, 15 October 2014
Earth and Planetary Science News

• Interstadial inland dune slacks in south-west Slovakia: a multi-proxy vegetation and landscape reconstruction

• P. Hájková, L. Petr, M. Horsák, J. Rohovec, M. Hájek

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Wednesday, 15 October 2014
Earth and Planetary Science News

• Snow and avalanche research: A journey across scales

• Jürg Schweizer

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Wednesday, 15 October 2014
Earth and Planetary Science News

• Source rock characteristics of the Lower Cretaceous Abu Gabra Formation in the Muglad Basin, Sudan, and its relevance to oil generation studies

• Yousif M. Makeen, Wan Hasiah Abdullah, Mohammed Hail Hakimi, Khairul Azlan Mustapha

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Wednesday, 15 October 2014
Earth and Planetary Science News

• The first farmers in Cantabrian Spain: Contribution of numerical chronology to understand an historical process

• Miguel Ángel Fano, Miriam Cubas, Rachel Wood

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Wednesday, 15 October 2014
Earth and Planetary Science News

• When technology joins symbolic behaviour: The Gravettian burials at Grotta Paglicci (Rignano Garganico – Foggia – Southern Italy)

• In Press, Corrected Proof, Available online 14 October 2014

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Wednesday, 15 October 2014
Earth and Planetary Science News

A novel experimental study of aeolian snow transport in Adelie Land (Antarctica)

• Alexandre Trouvilliez, Florence Naaim-Bouvet, Christophe Genthon, Luc Piard, Vincent Favier, Hervé Bellot, Cécile Agosta, Cyril Palerme, Charles Amory, Hubert Gallée

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Friday, 10 October 2014
Journal of Quaternary Science

A Middle Palaeolithic site in the southern North Sea: investigating the archaeology and palaeogeography of Area 240

The potential for Middle Palaeolithic sites to survive beneath the sea in northern latitudes has been established by intensive investigation within Area 240, a marine aggregate licence area situated in the North Sea, 11 km off the coast of Norfolk, England. The fortuitous discovery of bifacial handaxes, and Levallois flakes and cores, led to a major programme of fieldwork and analysis between 2008 and 2013. The artefacts were primarily recovered from Marine Isotope Stage 8/7 floodplain sediments deposited between 250 and 200 ka. It is considered that the hand axes and Levallois products are contemporaneous in geological terms with taphonomically complex sedimentary contexts, as observed in several north-west European sites. The Early Middle Palaeolithic (EMP) lithics have survived multiple phases of glaciation and marine transgression. The investigations confirm that the artefacts are not a ‘chance’ find, but indicate clear relationships to submerged and buried landscapes that, although complex, can be examined in detail using a variety of existing fieldwork and analytical methods. The palaeogeographical context of the finds also offers expanded interpretations of the distribution of EMP hominins in the southern North Sea, not predictable from onshore archaeological records.

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