Late Cretaceous Sedimentary Responses To The "Coast Range" And Paleoclimate Changes In Southeast China

Due to crust isostasy in the Late Cretaceous. Consequently, huge molasses had been deposited in front of the "Coast Range", where the paleo-environment and paleoclimate would be affected profoundly.This dissertation focuses on the terrestrial strata sequences during the Late Cretaceous period in Southeast China. Based on fieldwork and new data collected, stratigraphy, lithology, sedimentary facies, sedimentary flux as well as paleoclimate were studied and discussed.Some results and preliminary conclusions are listed as follows:Six sedimentary cross-sections were investigated, for which lithofacies are classified by means of lithogical features and structures. Study area in the Upper Cretaceous can be devided into alluvial fan, lacustrine and fluvial facies.Shape, size of twenty-eight basins and thickness of the main sections from these basins are accounted. Based on new data, average sedimentary thickness of each basin, areas of every basin and Sedimentary flux of these basins are calculated. The gross sedimenatary flux of these basins are 48.51×10~3 km~3. According to the principle of mass balance, mechanical denudation flux of the "Coast Range" in the Late Cretaceous are calculated as 97.02×10~3 km~3. By camparing wih fluvial denudation rates in major world drainage basins, chemical weathering budget are calculated as 10.78×10~3 km~3. Then, the gross denudation flux of the "Coast Range"in southeast in Late Cretaceous is 107.80×10~3 km~3. Based on gross denudation flux, the models of "Coast Range" in the earlier in the Late Cretaceous and present are designed, and the scale of "Coast Range" in Southeast China in the Late Cretaceous was estimated as higher than 2500 m.By gathering abundant imformation of paleoclimate in cretaceous in Southeast China, combined with relative information from fieldwork, it is elementary concluded that paleoclimate is both dry and wet in earlier Cretaceous and dry and sweltering in the Upper Cretaceous.By comparision of lithofacies, paleoclimate evidence, sedimentary budget, It is supposed that there could be a coupling relationship between the evolution of paleo-environment and paleoclimate and uplift of "Coast Range".