On the time of the Altai mountain relief formation

Abstract

Analysis of the composition and occurrence of the Lower Cenozoic sediments reveals the Pre-Cenozoic age of the Altai Mountains, their structure being slightly complicated during the Cenozoic as a result of small-amplitude block movements. Late Cretaceous - Paleocene sediments (Karachum suite) present re-deposited Cretaceous weathering crust and include pebbles and debris; they form piedmont aprons and lake basins filling. During their sedimentation the erosion areas (dissected mountains) were clearly distinguished from areas of sedimentation - intermontane depressions, their position being close to the present. While compared, the palynological evidences from the Chuya and Tarkhatinsk basins reveal the difference in the basins altitude about 600-1000 meters which is similar to the present one, the basins altitudes being thus commensurable to the present. The younger Paleogene and Neogene sediments analysis confirms the notion of the permanent existence of the same pattern of mountain and depression relief. The conclusion on the older age of the modern topography than it had been previously suggested corroborates the evidences from the Tien-Shan and Pamir, and throws doubt upon the existence of the Early Cenozoic epoch of planation on global scale.