Abstract:

A set of the mixed clastic-carbonate deposits were developed in the Lower Cretaceous of Erlian Basin. 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 recognized: (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.

Key words: dolomitic rock, parent material mixing, tuffaceous composition, buried dolomitization, the Lower Cretaceous, Erlian Basin