Abstract:

Thrombolite is a non-laminated fabric of microbial carbonate, which is in a sharp contrast with stromatolite that is characterized by the laminated fabric. Thrombolite bioherm developed in Cambrian Zhangxia Formation in the western Shandong Province mainly consists of clots, which are composed of dense micrite and microspar. Both the remain of calcified extracelluar ploymers (EPS) and calcified cyanobacteria fossils are observed within the clots that make up thrombolite. Within the complex microscopic fabrics it can be observed that the remain of calcified EPS is marked by the spherical structure, the sheet structure, the mat structure and the honeycomb-like structure, and it further indicates that the formation of clots within thrombolite should belong to a complex organic mineralization process. Together with both the dense micrite and the calcified cyanobcteria fossil, the calcified EPS provide some important information for understanding the enigmatic formation mechanism of thrombolites. Therefore, the study of Cambrian thrombolite bioherm can provide an important clue and approach for the further research.

Key words: calcification, thrombolite, Zhangxia Formation, western , Shandong Province