Pleistocene climate change, natural environments and Palaeolithic occupation of East Kazakhstan

摘要

The territory of East Kazakhstan (the Southern Altai Mountains, the Bukhtarma and Zaisan/Black Irtysh Basins), still insufficiently investigated because of its proximity to the Kazakh-Russian-Chinese border zone, shows a complex Quaternary history and the associated environmental transformations reflected by intensive geomorphic processes related to the past global climate evolution in conjunction with the regional neotectonic activity. The marked climatic changes are indicated by the preserved palaeoland-scape forms in both the mountain and steppe regions, as well as by the glacial and sedimentary geology, palaeoecology and geoarchaeology proxy records indicating long-term variations in temperature as well as humidity. Following the generally warmer Early Pleistocene climates, witnessed by the distribution of deeply weathered red palaeosols, the increased continentality and relief gradient during the Middle and particularly the Late Pleistocene led to establishment of the present-type forest-steppe/semi-desert during warm stages, and the periglacial arid steppe during cold stages correlated with the glaciations in the southern Altai Mountains, and loess deposition in the foothills. The mapped glacigenic and high-resolution loess-palaeosol sections, and contextual environmental archaeology data from the Pleistocene occupation sites provide new evidence of a rather pronounced natural dynamics. Spectacular glaciofluvial terraces in the principal mountain valleys indicate the presence of deep ice-dammed last glacial lakes documented from other parts of the Altai that were subjected to cataclysmic drainages during deglaciations. The recently discovered localities in the Bukhtarma River valley in diverse settings bear witness of a much earlier (Middle-Upper Palaeolithic) inhabitation of this geographically marginal area and adaptation to local mountain and steppe environments predating the Holocene prehistoric cultures. This paper summarizes some results of the initial multidisciplinary Quaternary field studies in the southern Altai region of East Kazakhstan and the adjacent part of Gorno Altai (2003-2007).