沔阳—当阳中生代前陆盆地构造特征及油气勘探

沔阳—当阳前陆盆地自北而南可划分为五个构造单元 :桐柏山—大别山基底卷入推覆构造带、南大巴山—大洪山叠瓦逆冲断裂构造带、沔阳—当阳拗陷变形带、宜昌—沙市前陆斜坡带、黄陵—松滋前缘隆起带。盆地的形成与南大巴山—大洪山造山带的发育密切相关。盆地经历了加里东期、海西—印支期南秦岭洋盆、北华南洋盆的两次“开 (降 )、合 (升 )” ,燕山早期陆内俯冲造山成盆及燕山晚期—喜马拉雅期陆内伸展断陷的演化。盆地油气资源丰富 ,具三套有效烃源岩 :晚奥陶世—早志留世广海陆棚相泥页岩 ,二叠纪滨岸沼泽相含煤泥岩 ,晚三叠世—早侏罗世湖泊—沼泽相暗色泥页岩、煤系泥岩和煤岩。中三叠世—早第三纪为油气生成高峰期。油气运移指向主要为南西方向的前缘隆起

Tectonics and Oil Exploration of Mianyang-Dangyang Mesozoic Foreland Basin/

Mianyang-Dangyang Basin can be divided into five tectonic belts. Formation of the basin is closely relative to the development of the South Dabashan-Dahongshan Orogenic Belt. The tectonic evolution of it experienced twice opens and twice closes of ancient ocean basins during Caledonian and Hercynain-Indosinian epochs, formation of the intracontinental orogenic basin by subduction during early Yanshan, and intracontinental extending and faulting during late Yanshanian-Himalayan. In the basin that possesses of rich hydrocarbon resource, there are three sets of effective source rocks, which are the Late Ordovician-Early Silurian sea shelf argillaceous shale, the Permian shore marsh coat mudstone and the Late Triassic-Early Jurassic lacustrine-mash dark argillaceous shale, coal measures mudstone and coal rock. The Peak of hydrocarbon generation was during Middle Triassic-Paleogene stage and the hydrocarbon mostly migrated southwestwards to the frontal uplift.