试论南中国海盆地新生代板块构造及盆地动力学

On the Cenozoic tectonics and basin dynamics of the South China Sea

南海地处欧亚、印度—澳大利亚和菲律宾海板块的交互带,是西太平洋地区面积最大的边缘海之一,其成因机制和演化过程对探讨特提斯构造域和太平洋构造域相互作用及油气勘探等问题具有重要意义,虽备受关注但仍存争议。综合目前该区及外围已有的大地构造等方面的资料,本文从探讨南海外围的构造格架及中-新生代演化过程入手,分析了南海及外围板块构造早第三纪、晚第三纪和第四纪期间的板块演化序列及相应的沉积过程,以期对南海盆地的成盆动力学过程提供约束和启示。此外,还进一步概括了南海北、西和南部大陆边缘性质及其相应的盆地变形特征。

The South China Sea is located at the conjunction of the Eurasia, India-Australia and Philippine plates, and is the largest marginal sea in the western Pacific area. The mechanism and tectonic evolution of the South China Sea, which will shed great insights into the interaction between the Tethyan and Pacific tectonic realms and the assessment of the oil and gas potential, are still open to intense debate. Based on the existing srtructural and tectonic information of the South China Sea and its adjacent areas,we tentatively dicussed the tectonic evolution of regions around the South China Sea during the Early and Late Tertiary through the Quaternary. The origin and evolution of the South China Sea were largely restrained by the India-Asian collision and the rotation of continental blocks along the Red River fault during the Cenozoic. South China Sea developed under the rift-strike tectonic background with the levorotaroty of Red River fault transfer to dextrorotation accompanying the convergency of India-Asian plate. Cenozoic subduction of the Pacific plate beneath to the Erasian continent result the disintegration of accumulated East Asian terranes during the Mesozoic. Continous continental subduction of South China Sea casused the underplate of basalt and uplifted the continental curst, and initite the broad magmatisms during the Mid-Miocene, and formed the miniature of modem South China Sea＇s deformation and tectonic framework. Generally, the South China Sea experienced initial marginal rifting in early and Middle of the Early Tertiary, strike-slipping pull-apart and oceanic extension during the later Early Tertiary to the early Late Tertiary, and Neotectonism from later Late Titary to Quaternary,respectively. Meanwhile, sedimentary sequences correspongding to the relevant tectonic setting. Cenozoic basins within the South China Sea have undergone different formation times, continental marginal deformation and basin characteristics because of the multiple plate tectonic dynamics around it. The northern South China Sea is a typical extensional continental margin result from the extension of oceanic crust, while its southeast is a compressional margin and its west is a transfer extensional continental margin.