摘要
为了明确南海西南次海盆V型尖端地壳岩石圈发生最终裂解的特征及其演化过程,通过精细的构造解释、断层活动性定量分析、不同构造演化阶段盆地原型分析、沉降速率分析、沉降史模拟等方法综合分析表明,南海西南次海盆V型尖端临界破裂区为远端带和洋陆转换带构成的地壳岩石圈强烈伸展区,依据地壳岩石圈几何形态,该区域可进一步划分为箱型域和楔型域。楔型域内盆地原型可划分为断陷盆地(Tb-SD)、拆离盆地(SD-PD)和拗陷盆地(PD-Bi);箱型域在古新世-渐新世(Tb-SD)盆地原型为断陷盆地,之后该区域进入被动沉降期。新生代以来,南海西南次海盆V型尖端在构造演化过程中,盆地沉降中心由陆向洋方向逐渐迁移,岩浆作用在断拗转换幕发育最强烈,致使岩石圈地壳最终发生裂解。区域资料对比分析表明,南海西南次海盆V型尖端在不同构造带内,盆地构造-地层格架具有差异性,且南海西南次海盆V型尖端经历“双拆离作用”后地壳发生破裂,岩浆侵入,形成原洋洋壳。该认识对南海西南部深水盆地内油气勘探具有重大指示意义。
To clarify the final breakup characteristics of the crustal lithosphere at the tip of the Southwest Subbasin in South China Sea and its evolution stages,this paper interpreted 2D deep seismic lines and analyzed the fault activities,the proto-basin type in different stages,the rates of subsidence and the history of tectonic and subsidence evolutions.It was clear that the distal domain and ocean continental transition consist of the final breakup zone of continental lithosphere at the tip of southwest South China Sea.According to the shape of the crust,this final breakup zone could be subdivided into a box domain,wedge domain and proto-oceanic domain.The basins within the wedge-shaped domain had been divided into the rifting basin(Tg-Sd),the detachment basin(Sd-Pd),and the sag basin(Pd-Bi).The basins within the box-shaped domain were of the rifting type from the Paleocene to Oligocene(Tg-Sd)and then transitioned to the passive sedimentation stage.From the Cenozoic,the sedimentation center on the tip of the Southwest Subbasin migrated from continental to ocean during the tectonic evolution of this region.The magmatism developed strongly and finally broke up the continental crust.The comparison of high-resolution seismic data showed that the tectono-sediments and magma type were different within different domains at the V-shape tip of the Southwest Subbasin.The continental crust of the research area broke apart after the"double detachment faulting".Then,the magma came in and formed the proto-oceanic crust.The research in this paper was of great value for oil and gas exploration in the deep-water basin in the southwest South China Sea.
作者
罗盼
高圆圆
王厚金
任建业
Luo Pan;Gao Yuanyuan;Wang Houjin;Ren Jianye(SINOPEC Geophysical Research Institute Co.,Ltd.,Nanjing 210013,China;College of Marine Science and Technology,China University of Geosciences(Wuhan),Wuhan 430074,China;Hubei Key Laboratory of Marine Geological Resources,China University of Geosciences(Wuhan),Wuhan 430074,China;Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou),Guangzhou 511458,China)
出处
《地质科技通报》
CAS
CSCD
北大核心
2023年第2期234-246,共13页
Bulletin of Geological Science and Technology
基金
国家自然科学基金项目(41830537)。
关键词
西南次海盆V型尖端
地壳破裂
双拆离作用
原洋洋壳
V-shape tip of the Southwest Subbasin
breakup of continental crust
double detachment
proto-oceanic crust
