南海南、北陆缘中生代构造层序及其沉积环境

新生代海底扩张，使南海陆缘分为南、北两部分。南部礼乐地块与南海北缘在扩张之前构成了统一的活动陆缘。通过对南、北陆缘的钻井研究和井旁地震剖面解释，发现二者的中生界均具有4 个地震层序及3 个构造层。南北陆缘构造层序及物源分析表明，早白垩世礼乐地块与南海北缘曾发生碰撞拼贴。早白垩世的南海北缘地区沉积环境由海陆过渡相向陆相演化，相应的礼乐地区是由浅海相向滨海相演化，二者反映出相同的向上变浅旋回，说明在南、北陆缘拼贴之后，两者具有了统一的构造沉积背景。到晚白垩世末，两区均隆升为陆，且遭受剥蚀; 南海北缘地区上白垩统部分被剥蚀，而距俯冲边界更近的礼乐地区上白垩统则被剥蚀殆尽。

Mesozoic tectonic squence of southern and northern continental margins of South China Sea and their depositional environment

Continental margin of South China Sea was divided into two parts for seafloor spreading in Cenozo- ic. Liyue block and continental margin of northern South China Sea should be the same margin before seafloor spreading. Based on drilling data from northern and southern continental margins of South China Sea and seismic profile interpretation across the wells, Mesozoic strata are derided into four seismic sequences and three structural layers. Tectonic sequences and provenance analysis of northern and southern continental margins showed that the Liyue block and continental margin of northern South China Sea collided in Early Cretaceous. In Early Cretaceous, depositional environment in continental margin of northern South China Sea evolved from marine-continental transi- tional facies to continental facies, and Liyue area from shallow sea facies to littoral facies correspondingly, which showed the same upward shoaling cycle, indicating the two areas had unified tectonic and depositional setting after the collision of northern and southern continental margins. By the end of Late Cretaceous, the two areas upheaved to be continent and have been destroyed, which caused that partial Upper Cretaceous strata in northern continental margin of South China Sea was destroyed and complete Upper Cretaceous strata in Liyue area closer to subduction boundary was destroyed.