郯庐断裂带对合肥盆地油气地质条件的控制

A RELATIONSHIP BETWEEN THE TAN-LU FAULTED BELT AND THE PETROLEUM GEOLOGY OF THE HEFEI BASIN

郯庐断裂带的左行平移发生在早白垩世,并将大别—胶南造山带左行错开。该断裂带的平移在合肥盆地东部控制发育了早白垩世的走滑盆地,其中沉积了朱巷组地层。早白垩世走滑盆地内的半深湖—深湖环境下,形成了一套最大累计厚度达600m的暗色泥岩,属于腐殖型的较差烃源岩。郯庐断裂带晚白垩世—老第三纪的伸展运动,在合肥盆地东部控制形成了半地堑式断陷盆地,分别沉积了上白垩统响导铺组、张桥组和下第三系定远组。响导铺组和定远组中形成的烃源岩最大累计厚度不超过200m。新第三纪以来,随着中国东部受压、郯庐断裂带的逆冲活动,合肥盆地随之消亡。合肥盆地最有前景的勘探目的层应为石炭—二叠系含岩系。今后应加强对这套地层的构造、沉积相、煤生烃、二次生烃潜力的研究。

According to isotopic dating, sinistral displacement of the TanLu faulted zone took place in the Early Cretaceous. The movement offset sinstrally the DabieJiaonan Orogenic Belt. The displacement of the faulted zone controlled the development of the strikeslip basin in the eastern part of the Hefei Basin in the Early Cretaceous. The strikeslip basin was filled with deposits of the Zhuxiang Formation. Dark mudstone with a total thickness of 600m was deposited in the environment of deep lakes in the Early Cretaceous strikeslip basin. During extensional movement of the TanLu Fault from the Late Cretaceous to the Paleogene, a faulted halfgraben basin was developed in the eastern part of the Hefei Basin. It was filled with the Xiangdaopu and Zhangqiao Formation of the Late Cretaceous and the Dingyuan Formation of the Paleogene. Dark mudstone was found in the Xiangdaopu and the Dingyuan Formation, and that from the Dingyuan Formation in the Shucheng Depression has better quality. With compression movement in East China and thrusting activities of the TanLu faulted zone since the Neogen, the Hefei Basin terminated its development. In terms of hydrocarbon exploration, more attention should be paid to the Shucheng and the Daqiao Depression.