Abstract:
Based on the comprehensive studies of petrology, carbon and oxygen isotopes, and cathodoluminescence characteristics, it has been shown that dolomites from the Jingzhu and Zhongba outcrop sections of the Cambrian Loushanguan Group have experienced multiple diagenetic effects such as dolomitization, dissolution, cementation and silicification. There are four types of dolomite: penecontemporaneous, seepage refluxing, buried, and hydrothermal. Four diagenetic stages were divided into penecontemporaneous, early, late and epidiagenetic. The influencing factors of diagenetic evolution and pore development were analyzed. Diagenetic evolution was mainly affected by the sedimentary environment, the original structure of sediments and sedimentary cycles. Micrite dolomites formed in tidal flat and lagoon environments have a poor original porosity, and the late diagenetic fluid alteration was weak. Grain dolomites and crystalline dolomites formed in a beach environment have lots of primary pores, and their porosity was further improved by late diagenetic fluid alteration. As a result, they are more favorable reservoirs for oil and gas.