The Study On The Comprehensive Strata And Lithofacies Palaeogeography Of The Carboniferous In Baoshan, Western Yunnan

Baoshan block is located in westward of Yunnan province,and it develops Xiangshan formation and Pumenqian formation in the carboniferous from bottom to up, and lacked of the upper carboniferous. Six three-order sequences is distinguished in the area early during carboniferous epoch, and the early carboniferous has six sequences, while the late carboniferous is missing. And the span of a single sequences is roughly 5 Ma.The researched sequences which develop in the deep-water environment are mainly consisted of only TST and HST in term of a single sequence, while LST grows little, and the characterater of sequence structure is for TST < HST.According to palaeogeographic pattern of the baoshan block that the west is continent and the east is ocean,the article has undertaken to three-order-sequence comparison in different sedimentary environment from the west to the east, and establishs sequence stratigraphic frame,which reflects that the early carboniferous in baoshan district has six depositional cycle of transgressed-regressive process.Carbonate sedimentary type has been made in the study area, that is the terrace mode of having a platform-margin slope.during the turn of devonian and carboniferous, Baoshan block uplifts, and to the middle-late carboniferous, it begin to experiences a regressive process, then study area accept deposition of bathyal – shallow water platform edge slope or shoal phase in early carboniferous epoch,which is mainly powder crumbs limestone,icritic limestone, oolitic limestone and bioclastic limestone,etc. its sedimentary facies belt is distributed in the way from north to south.To the late carbonifous,Baoshan block uplifts again and is missing of sedimentary record.