二连盆地下白垩统湖相云质岩分布及控制因素

Distribution Characteristics and Controlling Factors of the Lower Cretaceous Lacustrine Dolomitic Rock in Erlian Basin

二连盆地下白垩统发育一套陆源碎屑成分和碳酸盐矿物组成的混合沉积,且近年来在其中发现大量油气显示,但目前对这套混合沉积的研究程度较低。通过岩心观察、薄片鉴定、测井等方法,对巴音都兰、阿南和额仁淖尔等多个重点凹陷内云质岩的岩石学特征、分布特征等进行研究,认为:云质岩分布主要受母源区岩性控制,为典型的母源混合类型;湖盆演化类型不同导致沉积相发育的差异性,进而决定云质岩纵向分布;火山玻璃脱玻化为埋藏白云化作用提供大量Mg2+、Fe2+离子,导致白云石中铁含量高;古气候对云质岩分布的影响较弱。

A set of the mixed clastic-carbonate deposits were developed in the Lower Cretaceous of Erlian Ba-sin.In recent years,abundance of hydrocarbon shows have been found in the dolomitic rocks,but there is little research on this kind of mixed deposits.Therefore,combined with core observation,microscopic identification and bore log analysis,we made a comprehensive study of petrologic features and distribution of mixed clastic-carbonate deposits in the main sags.According to this study,some knowledge on the dolomitic rocks were rec-ognized:(1 )Dolomitic rocks mainly affected by the source area lithology is typical parent material mixing.(2) Different types of lacustrine basin evolution lead to sedimentary facies differences,which determine the vertical distribution of dolomitic rocks.(3)Devitrification of volcanic glass provides a large number of Mg2+and Fe2+ions for buried dolomitization,resulting in the high iron content of dolomite.(4)Distribution of dolomitic rocks is less affected by paleoclimate.