中国油页岩富集与地质事件研究

油页岩是一种有机质富集的细粒沉积岩,高古湖泊生产力和稳定的还原环境是油页岩成矿的关键。越来越多的学者研究发现,在含油页岩沉积组合序列中,经常出现火山、热液、大洋缺氧、气候突变、海侵、重力流等地质事件。通过对全国50个盆地、95个含矿区油页岩成因和分布规律的总结和归纳,揭示出火山、热液、大洋缺氧、气候突变、海侵、重力流等事件不同程度地改变古湖泊水体条件,引发湖泊表层高生产力,促进藻类勃发和微生物繁盛,并形成稳定的湖泊分层环境,成为油页岩富集的有利因素。但若过量的火山灰、频繁火山爆发释放大量气体、高温高压的间歇性热液流体以及频繁的重力流作用将不利于油页岩富集。针对这些地质事件研究,目前还只停留在对单个事件的分析,未来需要从地球系统科学整体出发,促进沉积学、地球化学、微生物学等多学科交叉,揭示非常规油气资源沉积富集与重大地质环境突变的生态循环过程,进一步深入加强多种地质事件耦合作用对油页岩成矿影响,丰富非常规油气沉积学理论。

Oil Shale Mineralization and Geological Events in China

Research findings increasingly indicate that geological events such as volcanic action,hydrothermal fluids,ocean anoxia,climate mutation,transgression,gravity flow and so on are frequently evident in the sedimentary sequences of oil shale(a type of fine-grained sedimentary rock rich in organic matter).High paleolake productivity and a stable reducing environment are important considerations for oil shale mineralization.A summary of the genesis and distribution behavior of oil shale in 50 basins(95 mining areas)in China reveals that the geological events listed above have led to various degrees of algal and microbial blooms which changed the water conditions in ancient lakes and formed the stable layered lacustrine environments that are important for oil shale mineralization.However,frequent volcanic eruptions release large amounts of gas and ash,and intermittent hydrothermal fluids at high temperature and pressure.Also,frequent gravity flow is not conducive to oil shale enrichment.The present study focuses only on a single event.In future it will be necessary to promote interdisciplinary studies of sedimentology,geochemistry and microbiology from the perspective of earth system science to reveal the ecological cyclic accumulation processes of unconventional oil and gas resources and major geological environment mutation.This will add to our understanding of the combined effects of various geological events on oil shale mineralization,and enrich the theory of unconventional oil and gas sedimentology.