陆相湖盆海侵事件对烃源岩发育影响机制

    Influence mechanism of transgressive events on source rock development in continental lacustrine basin

    • 摘要: 海侵是影响湖盆烃源岩发育的重要事件之一,通过调研国内外相关文献,述评了这一领域的研究现状。海侵事件广泛分布于中国的松辽盆地、渤海湾盆地和苏北盆地以及国外多个盆地,海侵可通过古遗迹标志、矿物岩石学标志以及地球化学特征等识别。其次海侵烃源岩一般具有有机质丰度较高、有机质类型较好的特征,主要归因于海侵事件明显促进烃源岩发育,海侵作用一方面可能为湖水带来了大量的营养物质,显著提高了古湖泊生产力,另外一方面,盐度可能有利于形成稳定的水体分层,在水底形成强还原环境,促进有机质保存。以西非裂谷盆地(Termit盆地)为例,总结了海侵影响湖相烃源岩发育的模式。

       

      Abstract: Transgression is one of the important events affecting the development of source rocks in lacustrine basin, and the status quo of this issue was reviewed upon summarizing relevant literature in China and the world. Transgressive events are widely distributed in the Songliao Basin, Bohai Bay Basin, Subei Basin in China, and many other in other countries. Transgression can be identified by paleorelic markers, mineral petrological markers, and geochemical imprints. Generally, transgressive source rocks are characteristic of high abundance and good type of organic matter, which is mainly due to the obvious promotion by transgressive events to the development of source rocks. On the one hand, transgression may bring abundant nutrients to lake water and significantly improve the productivity of ancient lakes. On the other hand, salinity may be conducive to the formation of stable water stratification and a strong reducing environment at the water bottom, which could promote the preservation of organic matter. Taking the Termit Basin in the West African rift type as an example, the model of marine transgression affecting the development of lacustrine source rocks is summarized.

       

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