Discovery of Microbial Mounds and Its Geological Significance

A complete and continuous Cambrian system can be found in the Qinglongshan Profile and the Xiweikou Profile in the Ordos Basin. There are five strata in total, namely, the Lower Cambrian Mantou Formation and Maozhuang Formation, the Middle Cambrian Xuzhuang Formation and Zhangxia Formation, and the Upper Cambrian Sanshanzi Formation. The microbial mounds of the two profiles were developed in the Mantou Formation of the Lower Cambrian and the Xuzhuang Formation of the Middle Cambrian respectively. The columnar stromatolites formed by microbial mounds mainly developed in the high energy intertidal environment, which is indicative of the paleoenvironment. In this study, field observation, systematic sampling and measurement of the microbial mounds in the Qinglongshan and Xiweikou Profiles in the Ordos Basin were carried out. Moreover, the macroscopic and microscopic characteristics of stromatolites were systematically analyzed from the perspective of geobiology, based on the previous research results and combined with the sedimentological characteristics of the profile. The discovery of microbial carbonates in the Qinglongshan Profile and the Xiweikou Profile in the Ordos Basin provides important rock records for understanding the earth’s microorganisms, paleoenvironment and paleoclimate in the Cambrian period.