Journal of Quaternary Science最新文献

The northern Upper Rhine Graben (Germany) contains a complex, quasi-continuous Quaternary record, but constraining its chronology is challenging. This study presents the first application of amino acid geochronology for this region using Bithynia opercula to establish a relative dating framework. Intra-crystalline protein decomposition (IcPD) results from opercula have allowed their horizons to be statistically grouped into clusters of equivalent age. Independent chronological evidence associated with these clusters was evaluated to refine the sediment chronology. This framework both constrains the ages of key lithostratigraphic units and facilitates cross-correlation of sediments across the graben, therefore providing a reference regional aminostratigraphy, which has also been extended to help constrain the age of nearby Palaeolithic sites. This approach shows the value of combining the multiparameter datasets from IcPD with other chronological evidence to cross-correlate boreholes, hence creating a reference dataset for Quaternary deposits for a given region.

The Florisian Land Mammal Age (FLMA; 773-12 ka) is characterised by specialist, often extinct, grazing as well as wetland species, many of which are no longer present in the southern African interior. Middle Pleistocene FLMA faunal assemblages are rare, particularly those associated with artefacts, limiting reconstruction of environmental conditions and hominin subsistence strategies. One exception is the faunal assemblages of Pniel 6 on the Vaal River, which are associated with Fauresmith lithics. Here, we present a comprehensive faunal analysis including stable isotope measurements and intracrystalline protein diagenesis (IcPD) analysis from several excavations since the 1980s. Twenty-one animal species were identified, with size class III bovids and typical FLMA species dominating. The results suggest a rich grassland environment supported by considerable water components. While most of the assemblage exhibits signs of a natural death assemblage, a few taphonomic modifications may indicate a human factor. Two distinct IcPD data clusters provide relative age estimates, suggesting that the teeth do not represent a single short depositional event. All results support the interpretation of Pniel 6 as a series of distinctive archaeological accumulations of human origin during the Middle Pleistocene, with a minor component of younger material mixed up close to the modern surface.

Desertification in North Africa has progressed rapidly over the past 6000 years. The occupation of Egypt by the Achaemenid Persians and Romans occurred even in hyperarid climates. Understanding the process of environmental changes on a regional scale may improve knowledge of how people developed technologies and adapted to the natural environment during a significant drying period. This study explored past environmental indicators from a sand profile at the foot slope of a Nubia sandstone ridge in Kharga, Western Desert, Egypt. The particle size distribution, free Fe oxide content, and mineralogical properties of magnetic spherical grains were analyzed alongside radiocarbon dating. Magnetic spherical grains, predominantly black with goethite as the primary mineral phase, exhibited micromorphological features resembling fungal durable structures. The presence of black-brown pigmented grains containing Mn and Fe indicated microbial activity in relatively humid environments. The ratio of Mn-type to Fe-type grain content has been proposed as a proxy for past environmental conditions preserved in sand deposits. A comprehensive analysis of the sand profile revealed an abrupt drying event around 5400 BCE, followed by a slight humid recovery around 4400 BCE in the Kharga Oasis.

Information on past sensitivity of the Greenland Ice Sheet to climate change is of importance for optimizing models simulating the future evolution of ice mass loss. While the ice-sheet change during the Lateglacial and Holocene is relatively well constrained, the long-term (multi-million-year) evolution of the Greenland Ice Sheet remains poorly known. In this study, we use in situ cosmogenic ¹⁰Be, ²⁶Al, and ¹⁴C nuclide concentrations from bedrock in Inglefield Land, western North Greenland, together with Markov chain Monte Carlo inversion to constrain the multi-million-year ice sheet history of this area. Our results indicate that the area became ice-covered for the first time at the beginning of the Quaternary and was glaciated for extensive periods during the Pleistocene. We cannot resolve whether the ice cover was confined to local ice caps or part of a larger ice sheet but only conclude that the ice cover was likely persistent with short interglacials. Further, our results show that the area has been characterized by low erosion rates (<1 m/Myr) during the past million years, suggesting cold-based ice similar to today's conditions.

The first high-resolution reconstruction of the vegetation and environmental changes during the last ca 13 300 cal a BP in the central part of the Kola Peninsula (NW Russia) was reconstructed based on sedimentary ancient DNA (sedaDNA) metabarcoding on sediment core Co1410 from Lake Imandra. In total, 204 taxa known from modern flora are identified. The resulting sequences were assigned to vascular plants (87%), bryophytes (12%), and algae (1%). About half (111 taxa, 49%) are identified at the species level. They belong to 150 genera and 86 families. So far, this is the most diverse and taxonomically detailed palaeoflora described for the Late Pleistocene–Holocene of the Kola Peninsula and North-European Russia. SedaDNA studies suggest that the vegetation cover in the region developed from (1) plant colonisation of the study area after the glacier retreated during the Allerød warming at ca 13 300–13 000 a BP to (2) Younger Dryas cold period with re-entering of the glaciers in the catchment of the Grater (Bolshaya) Imandra and establishing of the steppe–tundra communities. (3) Warming and increasing in vegetation diversity during the Early Holocene, with the formation of the birch forests by the end of this time zone. (4) Mid-Holocene temperature maximum is correlated with the highest regional plant diversity and a pronounced role of the thermophilic taxa, that is, Lonicera species, Prunus padus, Populus tremula, Sorbus sp./Cotoneaster sp. The highest so far revealed regional diversity of the higher spore plants (10) and aquatic plants (23) is evidenced. Mixed deciduous and coniferous forests were established in the research area during this period, and a drop in plant diversity occurred afterwards. (5) During the Late Holocene, modern communities are formed with a slight increase in biodiversity because of increasing input from cultural plants and weeds. Human impact is clearly diagnosed after 250 a BP, indicated by the presence of Ribes sp., Hypericum sp., and Mentha arvensis as well as eutrophic weeds, that is, Trifolium sp. and Urtica dioica. In addition, this study revealed the past dynamics of some plants rare for the Murmansk region, namely Pteridium aquilinum, with its maximum of occurrence at ca 11 000–8000 cal a BP and a strong decrease thereafter, and Nuphar sp./Nymphaea sp. occurring regularly since ca 7700 cal a BP and eliminating from the record after ca 3500 cal a BP.

The evolution of lakes in western Mongolia and their responses to climate changes and glacial meltwater input remain poorly understood. This study evaluates the reliability of multigrain and single-grain K-feldspar post-infrared infrared stimulated luminescence (IRSL) (pIRIR) dating applied to palaeoshoreline sediments at Khyargas Nuur, western Mongolia. It specifically focuses on assessing the extent of pIRIR signal bleaching and proposes an improved methodology for dating shoreline sediments where quartz is unsuitable for luminescence dating. Multigrain pIRIR signals measured at 150°C (pIRIR₁₅₀) and 225°C (pIRIR₂₂₅) were used to date Holocene and older samples, respectively. Single-grain pIRIR dating was conducted for the first time in the region to assess bleaching conditions and refine age estimates. Our comprehensive methodological approach was essential for constructing a robust lake level chronology. Single-grain measurements, combined with the application of the minimum age model (MAM), allowed us to identify and correct for incomplete bleaching in several samples. Notably, many of the multigrain aliquots showed no clear signs of poor bleaching in their equivalent dose (D_e) distributions, which would have resulted in significant age overestimation if single-grain data had not been available. Without this approach, the chronology of lake level fluctuations could have been significantly misinterpreted. By addressing this issue, we confidently date the highest lake level at ~129 m above modern lake (a.m.l) to marine isotope stage (MIS) 5 (~89 ka) and a subsequent highstand (~118 m a.m.l) to the Late Glacial (~14 ka). Following this highstand, lake levels declined rapidly (~25 m/ka), reaching ~20 m a.m.l through the Late Glacial to early Holocene transition. During the late Holocene, the palaeolake experienced a gradual regression to ~7 m a.m.l before reaching its current elevation of 1029 m above sea level (a.s.l).

There is little information about the changes in the abundance of mammalian species in South America during the late Quaternary, which is a key parameter to understanding past ecological and evolutionary dynamics. Here, we describe a conspicuous increase in the abundance of the gray brocket deer (Subulo gouazoubira G. Fisher, 1814; Mammalia) during the late Quaternary in Brazil based on paleontological evidence. We studied the material retrieved from pitfall deposits in Cuvieri Cave (Brazil) representing three time intervals (Late Pleistocene, Pleistocene/Holocene transition, and Holocene). The deposits in this cave were previously characterized in terms of facies composition, chronology, and overall taxa and taphonomy. We combined previous data with taxonomic identification at the species level for deer (morphological and ancient DNA analyses), quantification of the number of individuals for large mammals (>10 kg), taphonomic analyses, and stratigraphic distribution of specimens. Our results show that while in the Late Pleistocene gray brocket deer corresponded to up to 18% of 38 individuals, in the Holocene they represented at least 82% of 78 individuals. We interpret this change in frequency as a considerable increase in abundance in the surroundings of the cave, after excluding major taphonomical biases. The causes for this phenomenon are uncertain but could have involved a surplus of food availability and predation release due to the late Quaternary extinction event.

Southeast Asia is one of the most volcanically active regions in the world, yet their long-term eruptive history has been comparatively little studied. In particular, little work has explored the potential of sedimentary archives to record distal cryptotephra, which may help in identifying some of the region's larger Quaternary eruptions. Here, we report the finding of cryptotephra in a sediment core from Lake Towuti (Sulawesi, Indonesia). Based on glass geochemistry and core stratigraphy, we attribute the deposit to a ~120 ka eruption of Tondano, a large caldera situated on the Minahasa peninsula of Sulawesi. The minimal (~38 shards per gram) amount of tephra deposition hints at the limited ecological impact and/or magnitude of the eruption as well as establishing a new isochron that may enable synchronisation of late-Pleistocene sedimentary archives.