华南地区早古生代沉积演化与油气地质条件

Sedimentary evolution and petroleum geology in South China during the Early Palaeozoic

关键词:  扬子地块  早古生代  沉积序列  油气地质条件

Key words:  Yangtze landmass  Early Palaeozoic  depositional sequence  petroleum geology

摘要:

从构造角度上,现今的华南地区可以分为扬子地块和华夏地块,从成冰纪(南华纪)开始,由于受基底性质和构造活动等因素的影响,华南地区的沉积演化出现了分异,在扬子地块和华夏地块具有不同的沉积环境和沉积充填序列。总体上讲,扬子地块主体属于克拉通盆地,其多数时期为陆表海和局限浅海环境,构建了稳定的碳酸盐台地沉积和广泛分布的黑页岩沉积;而华夏地块处于构造活动环境,早期火山活动强烈,属于裂陷盆地,未形成统一的碳酸盐台地沉积,以陆源碎屑沉积充填为主体。两者不同的沉积环境和沉积序列决定了两个地区油气基本地质条件的差异:扬子地块具有丰富的烃源岩、良好的储集层以及封盖层的先天条件,而华夏地块没有较好的生油层和储集层。因此,在针对以早古生代地层为目的层的油气勘探工作部署时,应优先集中在扬子地块区。

Abstract:

Tectonically,the present-day South China area may be divided into the Yangtze and Cathaysian landmasses,where there existed distinct sedimentary environments and depositional-filling sequences influenced by the basement attributes and tectonism from the Nanhuan onwards.On the whole,the Yangtze landmass as a cratonic basin significantly consists of epicontinental sea and restricted shallow sea environments in which stable carbonate platform deposits and black shale deposits are well organized throughout the whole area.The Cathaysian landmass appears as a rift basin in the tectonically active environment,and is mostly built up of terrigenous clastic deposits rather than unified carbonate platform deposits.The individual sedimentary environments and depositional-filling sequences cited above are responsible for the differences of petroleum geology within individual landmasses.Tremendous source rocks,excellent reservoir rocks and favourable seal rocks are well represented within the Yangtze landmass,while within the Cathaysian landmass,no better source rocks and reservoir rocks have been displayed.It follows that the future targets for the petroleum exploration in South China should focus on the Early Palaeozoic strata within the Yangtze landmass.