THE PALEOGEOGRAPHIC CHANGES OF LATE PALEOZOIC IN QILIANSHAN REGION

The 506 pieces of section of Upper Paleozoic have been collected by the author to compile six lithofacies paleogeographic maps which can be summarized as follows: 1.After Qilian movement, ancient Qilian trench transformed into continent, and six deep N60° intermontane basins, trending parallel, with very thick sediments were formed. At the end of Late Devonian, elevation gradually appeared in the northern Qilian basin, while southern Qilian that had been paleoplain, became an intermontane basin. 2.In Early Carboniferous, the three southern Qilian intermontane basins were linked up by marine transgression, with Late Carboniferous further extended. Ancient Qilianshan was a wide and shallow epi-continental sea, which was connected with North China. The sediments,paleontologic groups and ore-bearing in the areas are very similar. 3. In Early Permian, the sea water receded southward, and the epicontinental sea of Northern Qilian became intermontane basin, the deposits are similar to that of North China. In Late Permian, Northern Qilian basin uplifted in the east, while southern sea area contracted and became asea bay. This is possibly caused by the controlling of Qi, Liu, Helan ε-type structures and Kang-Zang η-type structure.