Characteristics and genetic mechanism of dolomites of Lower Cambrian Xiaoerbulake Formation in Tarim Basin
The subsalt dolomites of Cambrian of Tarim Basin has huge potential of hydrocarbon exploration,but its exploration and development were constrained by the unclear genetic mechanism of dolomite.In this paper,by integrating outcrops of the northwestern basin with key well drilling data of the basin,on the basis of petrological analysis,and in combination with geochemistry analysis such as C,O,Sr isotopes,research on the genesis of the dolomite of Xiaoerbulake Formation was conducted and its genetic model was established.The results show that:(1)The dolomites of Xiaoerbulake Formation of Tarim Basin can be concluded into three types,namely microbial dolomites,crystalline-(residual)granular dolomites,and dolomites with continental clastics.(2)The dolomite of Xiaoerbulake Formation was mainly formed by three types of genetic models,namely microbial dolomitization,evaporative pumping-seepage reflux dolomitization,and burial-hydrothermal dolomitization.The former two were the main models and were superimposed and modified by the third one.(3)There are great differences between dolomite genetic models of Lower and Upper Xiaoerbulake Formation.During the sedimentary period of Lower Xiaoerbulake Formation,the high organic yield and the high rate of organic carbon burial in the water body were conducive to the development of anaerobic bacteria,which made microbial dolomitization dominate.During the sedimentary period of Upper Xiaoerbulake Formation,due to the shallowing of the water body,the whole environment became evaporative,and the intense evaporation resulted in the formation of a large set of evaporation pump-seepage reflux dolomite in Upper Xiaoerbulake Formation.The research results can provide theoretical support for the subsequent study on the distribution pattern of dolomites of Xiaoerbulake Formation in Tarim Basin.
万方数据
维普
