PLIOCENE AND PLEISTOCENE PALEOENVIRONMENTS OF THE TRANSBAIKAL AREA

During the Neogene the Transbaikal area was characterized by warm and humid climate with the predominance of the coniferous and broad-leaved forest and mesophitic vegetations (Logatchev et al., 1964; Belova, 1985). At the beginning of the Pliocene the climate changed towards cooler and arid. In the vegetations many thermophilic elements became reduce. However rather humid climate still existed to the Middle Pliocene and woodland predominated. It is evidenced by mammal associations and pollen flora known in Udunga locality of the region. The further tendency towards aridisation and cool condition is indicated by the mammal fauna of the following Chikoi complex which shows that the forest inhabitants are reduced significantly and savanna like forest steppe and steppe dwellers are flourished. At the Late Pliocene with the global cooling registered in the Baikal area at the age of 2.82-2.5 Ma (Karabanov et al., 1999; Prokopenko et al., 2001), the steppe inhabitants became dominant which evidenced by the Itantsinian faunas. With the progressive cooling at the beginning of the Early Pleistocene, the climate continued to change towards arid and the significant reorganisation in faunal assemblages occured. The most Pliocene taxa disappeared or replaced by advanced forms and the first appearance of lagurids, inhabitants of dry steppe, took place. At that time (1.75-1.4 Ma)another data of the cooling were recognized in the region (Karabanov et al., 1999) which led to the further aridisation. At the Middle Pleistocene in the fauna of Tologoi complex dry steppe and desert taxa became predominant. To the Late Pleistocene natural conditions of the region have changed towards more or less periglacial. The faunal analysis and ecological characteristic of main key taxa as well pollen data indicate that the alternation of the cold periglacial wormwood steppes and grass steppes with open woodlands took place in the area.