西藏东巧—北拉地区班公湖—怒江洋俯冲闭合及对南羌塘盆地演化的制约
The subduction and closure of Bangong Lake-Nujiang Ocean in the Dongqiao-Beila area,Tibet and its constraints on the evolution of southern Qiangtang Basin
张建勇 1许强 2曹雨 3熊绍云 1刘思琪 1谈轩宇 4谭秀成2
作者信息
- 1. 国家能源碳酸盐岩油气重点实验室;中国石油集团碳酸盐岩储层重点实验室;中国石油杭州地质研究院
- 2. 西南石油大学地球科学与技术学院;中国石油集团碳酸盐岩储层重点实验室西南石油大学分室
- 3. 西南石油大学地球科学与技术学院
- 4. 中国石化重庆页岩气有限公司
- 折叠
摘要
应用地层对比、砂岩岩相学和碎屑锆石U-Pb年代学的方法,重建东巧—北拉地区物源转换和班公湖—怒江洋多期次俯冲及微陆块的拼合过程.研究表明:东卡错微陆块南侧的中下侏罗统希湖群下段表现为上三叠统确哈拉群的再旋回沉积,而北侧上段则开始出现来自羌塘地区的物质.这标志着北侧早侏罗世俯冲的东巧分支洋盆消亡,东卡错微陆块在中侏罗世与羌塘地块拼合开始形成初始周缘前陆盆地.接奴群的物源完全来自南羌塘地区,表明周缘前陆盆地在微陆块南侧北拉洋俯冲挤压下持续发育.晚侏罗世—早白垩世(147～141 Ma)拉萨地块和羌塘地块东西向全面碰撞,至早白垩世晚期(约120 Ma)南侧的分支洋盆北拉洋消亡代表碰撞结束.南羌塘地区受班公湖—怒江洋俯冲作用控制在早侏罗世发育由弧前—岩浆弧—弧后盆地组成的"一隆两坳"古地貌,并沉积了曲色组页岩和布曲组石灰岩.微陆块碰撞导致南羌塘盆地的隆起和海平面的下降,形成夏里组含膏质泥岩的潮坪相沉积.随着拉萨地块和羌塘地块的全面碰撞,南羌塘盆地从弧相关盆地卷入前陆盆地褶皱冲断带中,发生差异埋藏和隆升剥蚀.晚侏罗世—早白垩世,南羌塘盆地曲色组烃源岩和布曲组石灰岩在构造挤压作用下发生快速埋藏,进入生油和白云石化阶段,成为南羌塘盆地最重要的成藏期.
Abstract
The Bangong Lake-Nujiang suture zone is an extreme important tectonic boundary in the Tibetan Plateau which is not only closely related to evolution of the Tethyan tectonic domain,but also directly controls the formation and inversion of the Mesozoic southern Qiangtang oil and gas-bearing basin.Based on stratigraphic correlation,sandstone petrography analysis and detrital zircon U-Pb dating,this paper reconstructs provenance changes in the Dongqiao-Beila area and reveals multi-stage subduction processes and microblock amalgamations in the central Bangong Lake-Nujiang Ocean(BNO).The BNO branch(Amdo Ocean)at Dongqiao-Beila area began to subduct in the Early Jurassic,resulting in amalgamation of the Amdo block to the southern Qiangtang terrane and rifting the Dongkaco microblock away from the northern Lhasa terrane and formed two new BNO branches of the Dongqiao Ocean to the north and Beila Ocean to the south.The lower Xihu Group close to the Beila suture in the south of the Dongkaco micoblock shows recycle deposits from the underlying Upper Triassic Quehala Group,while the upper Xihu Group close to the Dongqiao suture in the north of the Dongkaco microblock began to receive detritus from the southern Qiangtang terrane,indicating the Dongqiao Ocean demised and the Dongkaco microblock has amalgamated on the southern margin of the Qiangtang terrane with a peripheral foreland basin developed during the Middle Jurassic.Subsequent subduction of the Beila Ocean droved the Dongkaco microblock continuing to converge with south Qiangtang terrane in the Middle Jurassic and promote abundant materials from the south Qiangtang terrane transporting into the Middle-Upper Jurassic Jienu Group in the foreland basin on the Dongkacuo microblock.Wide collision between the Qiangtang and Lhasa terrane occurred during the latest Jurassic and Early Cretaceous(147-141 Ma)and continued during Aptian(ca.120 Ma)until the Beila Ocean finally dimed at Dongqiao-Beila Area.In response to multi-stage northward subductions of the BNO,the south Qiangtang Basin changed from passive continental margin to active continental margin during earliest Jurassic and developed arc-related basin system of east-west extending back-arc basin,volcanic arc and fore arc basin from north to south.The Lower Jurassic Quse black shale and overlying Buqu bioclastic limestone deposited in the back-arc basin.Continuous convergence and microblock collision contributed to rapid regression and uplift of the south Qiangtang basin,resulting in the deposition of tidal Xiali Formation with gypsum and mudstone during the Middle Jurassic.As the result of collision between the Lhasa and Qiangtang terrane in the Early Cretaceous,the south Qiangtang Basin evolved in fold thrust belt of the peripheral foreland basin and resulted in differential burial and denudation of the Jurassic successions.During the Late Jurassic-Early Cretaceous,the Quse black shale and Buqu bioclastic limestone were correspondingly buried rapidly due to the tectonic compression and entered the stage of oil generation and dolomitization,making it become the most important accumulation period in the south Qiangtang Basin.
关键词
班公湖—怒江缝合带/锆石U-Pb定年/俯冲闭合过程/物源转换/南羌塘盆地Key words
Bangong Lake-Nujiang suture zone/zircon U-Pb dating/the process of subduction and closure/provenance change/southern Qiangtang Basin引用本文复制引用
基金项目
中国石油前瞻性基础性重大科技项目(十四五)(2021DJ0801)
国家自然科学基金(42272257)
&&(42241202)
&&(42272237)
出版年
2024
国家科技期刊平台
NSTL
万方数据