Sedimentary records of high-mountain lakes in the arid Russian Altai – first results of multidisciplinary study (last glacial maximum – holocene)

Abstract

Sediment cores from three lakes in the Boguty depression allowed studying sedimentary records up to ~24 ka old in subaquatic sections up to 4.71 m long. This is the highest (2390–2470 m a. s. l.) and longest achieve of geochronological and paleoecological data for the neighboring arias of Altai, Tuva and Mongolia, which reflects the course of natural processes in the highest and most arid part of the Russian Altai from the Last Glacial Maximum till the present day. Paper reports estimations of the freshwater reservoir effect for the moraine-dammed Upper Boguty lake, which are 290 years for the present time, and about 1200 and 1300 years for the times ~5.7 and ~9.6 ka ago, respectively; chronological benchmarks (16–13 ka ago) for sedimentological transition zone between the late Pleistocene glacial-lacustrine clays and the Holocene biogenic-terrigenous silts, which was determined on the basis of multidisciplinary analysis; the size of glaciers in MIS-2 and in the Younger Dryas, as well as the time of thermokarst lakes formation (no later than 8.7 ka ago) within the upper terminal moraine complex; conformation of wide spreading of tree vegetation in the now treeless Boguty depression in the first third of the Holocene.