华南地区石炭纪-早二叠世早期成冰期的地球生物学过程与烃源岩的形成

Geobiological Processes and the Formation of Hydrocarbon Source Rocks in the Carboniferous-Early Permian Glacial Period in South China

石炭纪-二叠纪冈瓦纳大陆成冰事件控制着全球(尤其是华南地区)的海平面变化,从而决定着生境型及生产力的变化.冈瓦纳大陆成冰事件造成石炭纪-早二叠世早期有4次全球性海退,其中Tournasian末期到Visean早期的海退在华南地区最为明显,导致生境型发生了明显的变化.在盆地相区,由斜坡相(Ⅴ1)转变为下部浅海上部(Ⅳ1).在远岸碳酸盐台地区,由上部浅海(Ⅲ1)、(Ⅲ2)转变为潮间带(Ⅱ1)、潮下带(Ⅱ2).在连岸碳酸盐台地区,由浅水碳酸盐沉积区(Ⅱ1)、(Ⅱ2)转变为陆相或海陆交互相沉积区.通过对生境型、生物类群的分布及氧化还原环境的分析,探讨了冰期与间冰期生物群的演替、海洋生物生产力及埋葬条件的变化,进而确定成冰事件对烃源岩形成和分布的控制作用.

From Carboniferous to Early Permian, the glaciation of Gondwanaland played a crucial role in controlling changes of the sea level, the biohabitat types and the productivity, in particular in South China. Four global regression events identified during this period were attributed to the glaciation of Gondwanaland. In South China, the regression event occurred between the latest Tournasian and early Visean led to an obvious change of the biohabitat types. In the intraplatform basin, the biohabitat types shifted from V1 to Ⅳ1. In the isolated carbonate platform, the biohabitat types shifted from Ⅲ1-Ⅲ2 to Ⅱ1-Ⅱ2. In the carbonate platform connected with the land, the biohabitat types shifted from Ⅱ1 and Ⅱ2 to terrestrial or marine-continental sedimentary environment. Analyses of the biohabit at types, paleocommunities and redox conditions, enable us to investigate the paleocommunity evolution, the productivity of marine organisms and the changes of organic burial conditions in the glacial and postglacial period, and thus to explore the control of Carboniferous glaciation on the generation and distribution of hydrocarbon source rocks.