T146 Soils and Long-Term Environmental Change II

Wednesday, 28 October 2020
1:30 PM - 5:30 PM
Meeting Rooms

LATE PLEISTOCENE PEDOSTRATIGRAPHIC SEQUENCE AND PALEOLITHIC-MESOLITHIC OCCUPATIONS AT THE BEGANCHIK LOCALITY, MIDDLE VOLGA REGION, RUSSIA

Paper number: T146-2
Program: Technical Sessions
Time: 1:35 PM – 1:50 PM

Authors

Abstract

The Beganchik locality is situated on a peninsula in the Kuybishev reservoir near the mouth of the Aktai River in the Middle Volga Region. The locality is a former terrace of the Kama-Volga system, mantled by sequences of loess and alluvial sediments, and soil horizons encompassing the late MIS 6 to MIS-1. Wave erosion continuously creates slumps, producing fresh exposures with loss of bone, artifacts, and features. Our study applies Sfm photogrammetry to record stratigraphic sections and monitor changes. This presentation reviews the general stratigraphy and the importance of the site for paleoclimate and archaeological reconstructions.

Exposed at the bottom of the sequence is the Plio-Pleistocene Akchagyl Lake clays. In an abrupt unconformity on the clays lie loessial and alluvial sequences probably of the late MIS 6, which in turn grade into a truncated paleosol assigned to the penultimate interglacial MIS-5e (i.e., Mikulino). Above it lies a sequence of loess and alluvial sediment disturbed by periglacial features and a poorly developed soil (AC horizon). Radiocarbon dates from hearth charcoal on top of this soil produced a radiocarbon date around 40 ka. Associated with this soil horizon and the alluvium below are several lithic artifacts and megafaunal bone fragments.

Above the AC horizon lie several layers of loess and alluvium cut in some places by paleochannels. On top of an erosional unconformity along a broad channel is layer dated by associated lithics to c.12 ka. The uneroded equivalent layer on the paleo-terrace top presents a soil horizon with podzolic characteristics, suggesting presence of forest. Concurrent pollen from a contemporaneous sequence inland (Keremet) produced important amounts of Betula and Pine, suggesting the post-glacial establishment of forests. On top of the sequence the modern Chernozem soil developed. Present-day vegetation at the site is a dry, heavily grazed meadow with some steppic floral elements.

The relevant archaeological aspects of the sequence is the relatively early age (40 ka) for human presence at this latitude. This study attempts to study the chracteristics and geomorphic context of the AC horizon associated with the occupation, as well as paeleocological proxies such as pollen, spores, phytoliths, charcoal, and other microfossils.

Geological Society of America Abstracts with Programs. Vol. 52, No. 6

doi: 10.1130/abs/2020AM-358757

© Copyright 2020 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.