冰消期气候控制中国海相烃源岩有机碳富集
- 收稿日期:
2024-03-07
- 网络出版日期:
2024-07-24
摘要: 【意义】气候作用影响着海洋有机碳富集,现有文献主要探讨高日照量和温暖湿润气候下有机碳富集机理、总结富有机质沉积与天文周期间的关系,很少涉及冰消期海相烃源岩发育机理。我国在元古代和古生代冰消期发育了多套海相烃源岩,通过研究和总结冰消期气候对盆地有机碳富集的作用机理,有助于从地球系统的角度建立不同气候条件与有机质丰度之间的耦合关系模型。【进展】调研发现,我国大型油气田对应的中生代和新生代主力烃源岩发育于中高纬度温室气候期,而元古代和古生代主力烃源岩主要发育于中低纬度冰川消融期。冰消期烃源岩分布在新元古代、埃迪卡拉-寒武纪转换期、奥陶纪-志留纪转换期和二叠纪四个时代,其特殊的气候条件对海洋有机碳富集具有重要作用。米氏旋回控制下的高日照量、升温和波动气候导致的岩石风化增强、广泛的海侵作用、强烈的上升流作用和间冰期频繁的火山活动,共同导致了冰消期海洋生产力提高和缺氧还原的水体环境,进而促进有机碳富集和烃源岩形成。【结论与展望】这一冰消期气候与烃源岩形成的关系模式,体现了气候旋回控制下海洋-陆地-大气地球系统对有机碳富集的控制作用,未来可结合气候模拟和定量计算的结果,对大页岩油气田分布做出一定预测。
Enrichment of organic carbon in marine source rocks in China under the control of deglaciation climate
- Received Date:
2024-03-07
- Available Online:
2024-07-24
Abstract: Some studies suggest that there is a causal relationship between climate and organic carbon enrichment, but the relevant reports mainly focus on high temperature, high insolation, marine transgression, and cyclical patterns. A comprehensive model establishing the coupling relationship between different climate conditions and the abundance of organic matter in basins from the perspective of the Earth system has not yet been developed. The main source rocks corresponding to large oil and gas fields in China are distributed in various geological periods. Source rocks from the Mesozoic and Cenozoic are mainly developed during periods of high-latitude greenhouse climate, while source rocks from the Paleozoic and Precambrian are mainly developed during periods of deglaciation at mid to low latitudes. The distribution of source rocks during the deglaciation spans four periods: the Neoproterozoic, the Ediacaran-Cambrian transition, the Ordovician-Silurian transition, and the Permian. The unique climate conditions during the deglaciation play a crucial role in the enrichment of organic carbon. The warming and climate fluctuations during the deglaciation, along with changes in ocean currents and volcanic activity, collectively lead to increased productivity of water and oxygen depletion, thereby promoting the accumulation of organic matter and the formation of source rocks. This relationship model between deglaciation climate and source rock reflects the control of the Earth system of oceans, land, and atmosphere on organic carbon enrichment under the influence of climate cycles. It can be used to guide the discovery of major oil and gas fields. However, the contribution of each factor to organic matter enrichment still needs to be quantitatively analyzed through the establishment of ocean-climate models and productivity models.