Advances on Depositional Mechanism of the First Member of Lungmachi Formation and Advice for Future Studies

Abstract

The marine shale of Wufeng-Lungmachi Formation (WLF) in Middle and Upper Yangtze area is the reservoir for the biggest shale gas field outside North America. Clearly explaining the formation and distribution law of this set of high-quality shales is particularly essential. This article summarizes the advances on diverse lithofacies types, elemental geochemical analyses of paleo-productivity, redox conditions, and influence of special event-volcanic eruptions (represented by K-Bentonite). Moreover, this article also points out that, current “Formation (Member)” scale of studies cannot clearly explain the formation and distribution law of the high-quality shale required by commercial development and proposes that it is particularly urgent to carry out theoretical and practical studies on the main controlling factors of vertical heterogeneity of black shales, especially the first member of Lungmachi Fm.