UPPER CRETACEOUS-CENOZOIC CLAY MINERALS OF THE BAIKAL REGION (EASTERN SIBERIA)

Abstract

The Baikal region is located in a single climate zone and includes the Baikal foredeep on the eastern margin of the Siberian craton and the Baikal rift evolving at the western boundary of the Baikal orogenic area. Late Cretaceous–Cenozoic deposition in the two dissimilar tectonic units occurred in different environments, which is recorded in the architecture of sedimentary sequences and in the stratigraphic distribution of clay mineralogy.Clay minerals are mostly derived from weathered rocks of different ages. The geological ages of the source weathering mantles and their regular changes in different tectonic and climatic conditions can be inferred from the stratigraphic position in the Upper Cretaceous–Cenozoic sedimentary sequences that fill the Baikal foredeep. These inferences agree with data on fossil soils, flora, and fauna. Clay minerals show genetic relationships with stages of postdepositional alteration and processes of soil formation and hydrothermalism.In general, the Cenozoic history of erosion, deposition, and postdepositional changes of rocks in the Baikal region has been controlled by the interplay of climate and tectonic factors.