湖北宜昌地区下奥陶统碳酸盐岩成岩作用

湖北宜昌地区下奥陶统以碳酸盐岩沉积为主,成岩作用主要有胶结、压实、泥晶化、新生变形、硅化、溶解和白云石化作用,以胶结作用和白云石化作用最为广泛。成岩环境为淡水渗流带、淡水潜流带、淡水-海水混合带、海水潜流带与埋藏带。大多数成岩变化发生于淡水潜流带和混合带。

DIAGENESIS OF LOWER ORDOVICIAN CARBONATES IN YICHANG,HUBEI

The sequence of the Lower Ordovician in Yichang, Hubei is dominated by carbonates. The carbonates consist of allochems, such as bioclast, intraclast, pellet and ooid,abundant micrite and dolomite. The petrological characters indicate that the sequence was deposited in the carbonate platform-epeiric sea. The Lower part of the sequence mainly developed in shallow areas of higher energy, while the upper part in shallow shelf areas of lower energy, indicating the process of transgression. According to the conventional and cathodoluminescent petrography and stuble isotopes of carbon and oxygen, diagenesis, which includes the cementation, compaction, micritizatiom, neomorphism, silicification, dissolution and dolomitization, has been identified.The cementation and dolomitization are most common. The equant cement contains lighter δ