Journal of Quaternary Science最新文献

The scarcity of high-resolution palaeoclimate records from the interior of West Asia has limited our understanding of the mechanisms of past climate change and their potential impacts on early human societies of the Eastern Fertile Crescent. Here, we present a multiproxy sedimentological, geochemical and palynological record from the Hashilan Wetland in the central Zagros Mountains, spanning the time interval from 22 to 2.2 kcal bp. Our results indicate a cold, dry climate for the last deglaciation (22 to 10 kcal bp) with amplified aridity during the Last Glacial Maximum, Heinrich Stadial 1, the Younger Dryas and the 8.2 and 3.2 ka events. The Early Holocene (11.6 to 7.8 kcal bp) is characterised by prolonged dry summers, frequent spring/summer dust storms and restricted oak woodlands that gradually expanded as summers shortened toward the second half of the Holocene (<6 kcal bp). We show an out-of-phase Holocene moisture variation between the interior of West Asia and the Indian Summer Monsoon domain and conclude that summer insolation-driven latitudinal shifts of the Hadley cell played a key role in seasonality changes in the interior of West Asia by modulating the strength and pathway of the subtropical high-pressure cells. Finally, we explore possible impacts of these changes on regional prehistoric human communities.

Major shifts in hydroclimate have been documented during the last deglacial period and the Holocene in south-central Alaska. Rare freshwater calcium carbonate (marl) deposits in lakes on the Kenai Peninsula can be used to reconstruct past changes in hydroclimate, including the influence of groundwater inflow to lakes. Here, the postglacial sediment sequence from groundwater-fed Kelly Lake (60.514°N, 150.374°W) was analyzed for multiple proxies including isotopes of carbon and oxygen in marl calcite (δ¹³C_marl and δ¹⁸O_marl), and isotopes of carbon (ẟ¹³C_OM) and abundances of C and N in organic matter. Bulk sediment analyses include organic matter and calcium carbonate (CaCO₃) contents, visual stratigraphy and sediment flux. These analyses extend those of a previous paleoenvironmental reconstruction from Kelly Lake, which focused on sedimentary diatom oxygen isotopes and mass balance modeling over the past 10 000 years. Here, we show that Kelly Lake was deglaciated prior to 14.6 ka, and that by 14.0 ka marl dominated the sediments, with CaCO₃ precipitation probably driven by groundwater input and mediated by shallow-water charophytes. Marl accumulation decreased as organic and clastic inputs increased between ~12.2 and 11.5 ka. This shift, together with an increase in both δ¹³C_marl and δ¹⁸O_marl values and a decrease in CaCO₃ content, indicates an increase in the influence of meteoric water on the hydrologic budget under wet conditions, possibly driven by a strengthened Aleutian Low atmospheric pressure cell. A shift to lower δ¹³C_marl and δ¹⁸O_marl values at ~11.5 ka is interpreted as an increase in the proportion of groundwater relative to meteoric water in the lake. Beginning around 9 ka, the proportion of meteoric water input continued to increase, the surrounding coniferous forest was established, and by 8 ka, CaCO₃ accumulation ended. Our results elucidate the environmental conditions under which marl was deposited during the Lateglacial and early Holocene in this part of Alaska, and demonstrate how a variety of synoptic- and local-scale climatic variables can converge to influence sedimentation in a groundwater-fed lake.

Excavation campaigns conducted at the Pécel-Kis hársas site (Hungary) between 2014 and 2017 yielded the remains of a mature female woolly rhinoceros (Coelodonta antiquitatis) and six lithic artefacts. Radiocarbon dating confirmed that the rhinoceros died ca. 20.4k cal a bp, at the very end of the Last Glacial Maximum and, considering the position of the artefacts when found, it was probably killed by Epigravettian hunters. Based on dental analyses of the specimen, a vigorous lichen- (and possibly moss-)consuming diet could be inferred for the end of the animal's lifetime. Based on Sr results, we can exclude the possibility of long-range migration. In accordance with the optimum environmental demands of the foraging lichen, the low δ¹⁸O value of osseous material implies a relatively cold contemporaneous climate with a calculated mean annual air temperature of around 0.7 °C. Meanwhile, the extremely low δ¹⁵N value may have resulted from the proximity of the discontinuous permafrost zone and some intensive soil dislocation. Consequently, poor vegetation and an open, tundra-like habitat can be assumed to have been dominant at the site at that time, which is also supported by palaeoenvironmental modeling experiments.

In this contribution, we estimate the possible living body mass (BM) of the anancine gomphotheriid Anancus arvernensis, by testing a recently proposed volumetric method based on hyper-realistic in vivo 3D reconstructions and comparing the results with the BM obtained by using regression formulas. The analysis, conducted starting from two articulated skeletons, showed that the performance of regression formulas varies considerably from taxon to taxon, with plausible estimates obtained only when the mean of all the formulas on the individual bones is available and considered. Differently, formulas applied to single bones can lead to underestimations or overestimations of up to 300%, with BM ranging from 54 kg to 26 metric tonnes. By using the volumetric method, the in vivo reconstruction of Anancus arvernensis made it possible to estimate a BM between 5.2 and 6 t, a figure close to that of an extant adult male African elephant. The obtained results show that estimating BM in terrestrial tetrapods from single or fragmented bones might lead to highly improbable and misleading conclusions. Thus, in the presence of adequately complete mounted skeletons, it is always preferable and recommended to estimate the BM using the volumetric approach, which is based on an in vivo 3D reconstruction.

This study investigates paleoenvironmental changes at the Paleolagoa Seca site, an Upper Quaternary locality of lacustrine origin in central Brazil. We present charcoal and pollen analyses of this sedimentary sequence, and assess how they compare with previously published fossil macroflora and paleoclimatic reconstructions of the same site and adjacent localities. We identified a mosaic of savannas, forests and flooded environments before 43 ka bp with the presence of evergreen forest formations. For this period, we found charcoal particles resulting from natural fires that represent the oldest Quaternary record of fire in the Cerrado. By conducting a morphological analysis of charcoal particles, we were able to identify that the primary constituents of fire fuel were grasses, which suggests that surface fires were prevalent. During this Pleistocene wet phase, fire probably played a vital role in preserving areas of open vegetation. In contrast, at ~43 ka bp, an open landscape and a drier-than-present climate characterized the Paleolagoa Seca site.