柴达木盆地侏罗纪盆地原型及其形成与演化探讨

DISCUSSION ON FORMATION AND EVOLUTION OF JURASSIC BASIN-PROTOTYPE OF QAIDAM BASIN

胡受权 曹运江 黄继祥 牟中海

HU Shou-quan CAO Yun-jiang HUANG Ji-xiang MOU Zhong-hai

中山大学地球科学系, 广东广州市510275 2. 西南石油学院勘探系, 四川南充市637001

Department of Earth Sciences, Zhongshan University, Guangzhou 510275, China 2. Petroleum Institute of Southwest, Nanchong 637001, China

柴达木盆地的演变历程是与柴达木地块的发展历史一脉相承的。三叠纪及其以前,柴达木地块主体呈现稳定的隆升状态,仅其南、北缘发育的裂谷带时张时合,沉积了一套海相裂谷型建造。三叠纪末的印支运动结束了柴达木地块及其周缘地区的海相沉积史,使柴达木地区进入陆内盆地发育新时期。从柴达木盆地南、北缘推覆构造带形成的板块构造机理来看,柴达木盆地南、北缘各发育一个规模不等、但性质相似且具统一成因机制的陆相前陆盆地,且它们呈现背驮式渐次向前发展的模式。另外,由于阿尔金深断裂带在印支期和燕山期的强烈右型走滑作用,在柴达木地块西缘形成了一系列拉分盆地,使柴达木地块侏罗纪盆地原型具有前陆盆地与拉分盆地叠合的属性。白垩纪至早第三纪古、始新世,由于主干逆冲断裂带背驮式地向盆内发展,沉降沉积中心逐渐向盆内迁移;早第三纪渐新世以后,由于印度板块与欧亚板块的碰撞所引起的强烈挤压和盆内挠曲,前陆盆地及拉分盆地的特点已不明显,原来的前陆盆地和拉分盆地区成为了强烈构造变形带和晚第三纪-第四纪的局部沉积区。

Qaidam Basin evolution has come down in one continuous line with Qaidam Massif development. Before and in Triassic period, the main part of Qaidam Massif rose stably, but rift zones developed and received marine rift-typed sediments only at southern and northern borderland. At the end of Triassic period, the marine sedimentation on Qaidam Massif (including its surroundings) has ended, and interior basin started to develop in Qaidam area. In the light of the plate-tectonic mechanism to form the nappe structural zones at southern and northern borders of Qaidam Basin, the two continental foreland-basins which developed separately at southern and northern borders of Chaidamu Basin have similar characters and unified formation cause though their scale is different. And the foreland-basins appeared piggyback model and developed gradually towards inside basin. In addition, a series of pull-apart basins have formed at western border of Qaidam Massif. Therefore, Jurassic basin-prototype of Qaidam Massif is a superimposed basin of foreland-basin and full-apart basin. From Cretaceous Period to Paleocene-Eocene, subsidence and sedimentation area migrated gradually towards inside basin because the major thrust belts were piggyback and developed towards inside basin. After Oligocene, the natures of foreland-basin and pull-apart basin were on longer evident due to intensive compression and inside basin flexure caused by collision of Indian plate with Eurasian plate. And the former foreland-basin and pull-apart basin turned into intensive structural deformation zone and local sedimentary area for Neogene and Quaternary.

“油气藏地质及开发工程”国家重点实验室开放基金项目(PLN97025)成果之一

https://doi.org/10.11781/sysydz199903189