A Preliminary Study Of Sedimentary Environment From Cambrian (Series 2,Stage 4) "Tsinghsutung Formation" In Balang Area,Jianhe County,Guizhou Province

The Cambrian "Tsinghsutung Formation" crops out extensively in eastern Guizhou,it is perfectly exposed in the Songshan section at the Balang Village,Jianhe County."Tsinghsutung Formation" is 272 m thick.Base on the microfacies analysis of carbonate rocks,the sea-level change and sedimentary environment evolution of the Cambrian "Tsinghsutung Formation" have been reconstructed.Through the microfacies identification and analysis of carbonate rocks of "Tsinghsutung Formation" in Songshan section,5 kinds of microfacies of carbonate rocks have been recognized: According to Flugel,s work on standard microfacies type and its division of carbonate rocks,5 kinds of microfacies of carbonate rocks model can be assigned to three standard microfaciesSMF3?SMF5?SMF10,and dominated by SMF3 and SMF10,which refers to deposit at the edge of deep shelf facies(FZ3)or deep shelf facies(FZ2),only appears at the top slope facies(FZ4),reflecting the cyclical variation of except top sedimentary environment from edge of deep shelf to deep shelf of the research area.What's more,silt mudstone from the upper part of the “Tsinghsutung Formation”contains a Burgess shale-type Lagerstatte,known as the Jianhe biota.Specifically,the lagerstatte in the mid-upper part of "Tsinghsutung Formation" indicates rapid-burial event,causing fossil abundance and disparity suddenly increase in the mid-upper part of "Tsinghsutung Formation".In general,the sea level regarding the entire Tsinghsutung succession changes corresponding to three shallow periods and two deepening periods,respectively.Our study also indicates that the "Tsinghsutung Formation" sedimentary period sea floor may deposit above the redox surface and deposit nearby the redox surface.This study complement the sedimentology in "Tsinghsutung Formation".Futhermore,this study not only promote the GSSP work of Cambrian Stage 4,but also provided new information for the following reseach.