南海西北部新生代沉积基底构造演化

Tectonic evolution of Cenozoic sedimentary basements in the northwestern South China Sea

在综合分析地质、地球物理、地球化学、古生物学等多方面资料的基础上,将南海西北部海域控制新生代主要沉积盆地的基底划分为5个区:北部湾古生界断堑基底区、莺歌海古生界走滑拉分基底区、琼东古生界断陷基底区、西沙北古生界裂谷基底区、西沙南古生界走滑伸展基底区.通过区域地质分析,初步重建了该海域的大地构造演化历史.该海域新生代沉积基底在前新生代时期与其北面陆上云开地区和其南面的南沙地区同处于特提斯构造域中,经历过古特提斯和中特提斯的发育历程,晚古生代以来可初步分为5个阶段:(1)D-P1,古特提斯东段多岛洋体系发育阶段;(2)P2,中特提斯(古南海)开始出现、古特提斯开始消减阶段;(3)T-K1,古特提斯东段多地块缝合阶段;(4)K2-N11,现代南海形成、中特提斯(古南海)消亡时期;(6)N21以来南海扩张停止、澳大利亚板块向北俯冲挤压阶段.

On the basis of synthetical analyses of geology, geophysics, geochemistry, paleontology and paleomagnetism, the basements which control the major Cenozoic sedimentary basins in the northwestern South China Sea are divided into five districts: Beibu Gulf Paleozoic Erathem faulted basement district, Yinggehai Paleozoic Erathem strike-slip pull-apart basement district, Qiongdong Paleozoic Erathem rift-faulted basement district, northern Xisha Paleozoic Erathem rifted basement district and southern Xisha Paleozoic Erathem extended basement district. The evolution history of the basements is divided into five stages: (1)D-P_1,the stage of development of eastern Tethyan archipelago ocean; (2)P_2,the stage in which Meso-Tethys (Paleo-South China Sea) began to open and the Paleo-Tethys to subduct; (3)T-K_1,the stage in which the eastern Paleo-Tethyan blocks sutured; (4)K_2-N^1_1,the stage of the formation of modern South China Sea and the consumption of the Paleo-Tethys; (5)since N^2_1,the South China Sea stopped spreading and the Australia plate subducted and compressed northward.