摘要:
古南海的构造演化对研究大陆边缘张裂和盆地形成模式有重大意义。关于南海的构造演化过程尚存有争议,基于对前人研究成果的收集及综合比对,同时结合地震剖面分析,对逆断层和褶皱等挤压构造进行识别以及展布的刻画;并对南海北部古逆冲断裂带的展布及活动进行了深入研究。在确定晚中生代南海北部区域构造应力背景的基础上,在研究区内识别出了一条中生代逆冲断裂带,并对其位置、展布、活动停止时间进行了分析,对南海晚中生代以来的构造演化提出了新的模式:晚中生代以前,南海北部地区构造应力以挤压为主,存在着碰撞造山过程,形成了岛弧型活动大陆边缘;晚白垩世至始新世,盆地应力背景由挤压向张裂过渡,并存在至西向东的转换延迟;渐新世以后逐步转为拉张应力背景。
Abstract:
The tectonic evolution of the Paleo-South China Sea is of great significance to the study of tensile fractures on the continental margin and the origin of basins. Controversies about the process of the tectonic evolution of the South China Sea have appeared for a long time. In this article, based on the previous studies and comprehensive comparison, as well as seismic interpretation, the authors made a study on the reverse fault system and compression fold structures with special attention to the lateral distribution pattern of the paleo-thrust zone and its activities in the northern South China Sea. After determination of the tectonic stress background of the northern South China Sea in late Mesozoic, the authors identified a Mesozoic thrust zone. We made studies on its location, distribution, activity cut-off time of the thrust zone. Based on all the facts above, the authors reestablished a new model of evolution since late Mesozoic for the South China Sea. Before the late Mesozoic, the northern part of the South China Sea was predominated by a compressive stress and a collision orogenism. An island-arc type of active continental margin was then formed. From late Cretaceous to Eocene, the main stress of the basin was gradually transformed from compressive to tensional from west to east; After Oligocene, the study area is under a tensile stress.
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