Study on the paleoenvironment of Qigbulak Formation in Keping area,Tarim Basin
The division and correlation of Ediacaran-Cambrian stratum are controversial due to the lack of magmatic rocks and reliable chronological data.In this paper,the Qigbulak Formation of the Ediacaran-Cambrian is taken as the research object,detailed analysis of petrological features are conducted,and the validity of the carbon and oxygen isotope sampling data of carbonate rocks is evaluated by using the samples taken from the outcrop in Shiersk,northwest of Tarim Basin.The study of paleo-seawater salinity and temperature is carried out,and the causes of the carbon isotope positive anomalies in this formation are discussed,providing a reference for the stratigraphic division and correlation of Qigbulak Formation in the Ediacaran-Cambrian.The results show that:(1)The lower part of Qigbulak Formation was dominated by mixed sediments,which are thin interlayers of microbial dolomite,mixed rock and clastic rock.The middle and upper part mainly developed medium to thick bedded microbial carbonate rocks.(2)During the sedimentary period of Qigebulak Formation,the seawater temperature gradually increased and the salinity gradually decreased,and the salinity trend was more significant than that of temperature.(3)The carbon isotope positive anomaly in the lower part of Qigbulak Formation were closely related to the depositional environment.Terrigenous input promoted the increase of primary productivity,and the oxygen-poor condition of seawater further increased the amount of organic carbon buried and increased the δ13C in seawater,forming a positive anomaly at the bottom of Qigbulak Formation.
万方数据
维普
