南海北部陆缘深水-超深水盆地成因机制分析

本文以海洋地质调查和油气勘探开发中积累的地质和地球物理资料的解释和分析为基础，描述和划分了南海北部被动陆缘地壳岩石圈结构构造单元，由陆向海划分出近端带、细颈化带、远端带和洋陆转换带（OCT，含边缘高地）四个构造单元.从细颈化带到OCT基本处于现今陆架坡折带之外的深水-超深水区的范围，以强烈的地壳薄化和发育大型拆离断层控制的拆离盆地为特征.这些深水-超深水盆地的同裂陷阶段均经历了早期均一断陷、中晚期拆离式断陷的演化过程，受控于南海北部大型拆离断层作用及其所导致的岩石圈临界破裂过程.新的深水-超深水盆地形成机理的认识为南海北部陆缘岩石圈的非瞬时伸展破裂过程的分析提供了新的视角，同时，陆缘深水-超深水盆地具有独特的构造-沉积体系配置和构造-热演化过程，将为科学评价南海北部陆缘深水-超深水盆地油气勘探潜力提供新的思路.

Characteristics and formation mechanism of deepwater and ultra-deepwater basins in the northern continental margin of the South China Sea

This work is based on the interpretation and analysis geological and geophysical data collected by marine geological investigations and petroleum exploration and production. The purpose is to delineate the architectural elements of the northern continental margin in the South China Sea. From land to sea, this region can be divided into four first-order tectonic units, i.e. the proximal, necking, distal, and the Ocean-Continent Transition (OCT) (including Outer High) zones. The region from the necking to the OCT is largely located in the deepwater and ultra-deepwater area, almost in the southern present-day continental shelf break zone. This region is characterized by the hyper-extended continental crust where a series of large-scale detachment fault systems controlling the supra-detachment rift basin. At the syn-rifted period, the deepwater and ultra-deepwater basins all experienced initial uniform rifting and subsequently detachment rifting, which was related to the detachment faulting and final continental breakup in the northern South China Sea. This new understanding on the formation mechanism for the deepwater and ultra-deepwater basins provides new insights on the non-instantaneous continental extension in the northern South China Sea. In addition, these deepwater and ultra-deepwater basins show a typical tectono-sedimentary configuration and tectono-thermal evolution, which will provide new ideas for scientifically evaluating the potential petroleum exploration in deep/ultra-deep water basins of the northern continental margin of the South China Sea.