酒西拗陷下白垩统藻纹层发育环境及形成机制

酒西拗陷下白垩统纹层状泥质白云岩和白云质泥岩中藻纹层十分发育，主要由浮游藻类及其降解产物组成。藻纹层发育状况在很大程度上决定了该区下白垩统烃源岩生烃能力的大小，这也是烃源岩呈现出较强非均质性的一个重要原因。对酒西拗陷下白垩统藻纹层的发育条件及保存环境进行了研究，并对其形成机制进行了探讨。研究结果表明，早白垩世，酒西拗陷断陷湖盆水体广泛，适宜的温度、盐度等介质条件有利于藻类的大量繁殖，而水体分层的强还原环境对有机质的保存较为有利。湖泊水体的季节性更替及其引起的水体分层是该区藻纹层形成的重要原因。

DEVELOPMENT ENVIRONMENT AND FORMATION MECHANISM OF ALGAE LAMINAE IN LOWER CRETACEOUS IN JIUXI DEPRESSION

The organic matter laminae composed of algae and its decomposition products is very abundant in argillaceous dolomite and dolomitic mudstone of the Lower Cretaceous in the Jiuxi Depression. The development of algae laminae greatly enhances the hydrocarbon generating ability of source rocks in the research area and is one of important reasons why the source rocks are heterogeneous. In this paper, development and reservation environment and formation mechanism of algae laminae in the Cretaceous source rocks are discussed, and the formation mechanism of algae laminae is probed. The research results show that in the early Cretaceous, the capaciousness of lake water, moderate temperature and salinity are favorite for the algae blooming. However, the strong reductive environment made by layering of lake water is greatly of advantage to reservation of organic matters. Seasonal change of lake water and its layering are the important reasons of the formation of algae laminae.