地层记录中的古气候信息及其与烃源岩发育的相关性——以渤海黄河口凹陷古近系为例
Paleoclimatic information in stratigraphic records and its relation to the formation of hydrocarbon source rocks-A case study of the Paleogene strata in the Huanghekou subbasin of the Bohai Bay basin, China
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摘要: 近年来的研究表明，凹陷中优质烃源岩的形成决定于有利的古气候和古湖盆环境，并受控于断陷期快速沉降的构造背景。着重论述了古气候条件对烃源岩发育的控制作用。根据渤海海域黄河口凹陷典型钻井样品中的孢粉、藻类等古生物资料，并结合岩相特征，对该地区古近纪各时期的古气候、古环境特征进行了恢复，本区古近纪共存在4个气候湿热、古湖盆水体发育的时期。另外通过与烃源岩发育特征的对比，发现各湿热的古气候时期均与优质烃源岩的发育情况有很好的对应关系，说明温暖、湿润的古气候条件对烃源岩的发育具有重要的控制作用。最后对气候影响烃源岩形成和保存的机理进行了分析。Abstract: Recent study has revealed that the formation of good hydrocarbon source rocks in a subbasin depended on favorable paleoclimatic conditions and paleolake basin environment and was controlled by the tectonic setting of rapid subsidence during the downfaulting stage.This paper focuses on the controls of paleoclimatic conditions over the formation of hydrocarbon source rocks.According to the data of sporopollen and algae in samples from representative wells in the Huanghekou(Yellow River mouth) subbasin,Bohai Bay basin,and lithofacies characteristics of the area,the authors have reconstructed the paleoclimatic and paleoenvironmental conditions of the area in various epochs of the Paleogene.The results reveal that during the Paleogene in the Huanghekou subbasin there were four warm-humid stages when the paleolake basin water body developed.Furthermore,the four warm-humid paleoclimatic stages well correspond to four high-quality hydrocarbon source rock beds,which indicates that the warm-humid paleoclimatic conditions may have exerted important controlling effects on the formation of hydrocarbon source rocks.Lastly,the mechanism for the paleoclimate affecting the formation and preservation of source rocks is discussed.
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Keywords:
- sporopollen /
- paleoclimate /
- paleoenvironment /
- hydrocarbon source rocks /
- Huanghekou subbasin
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