海相油气地质2024，Vol.29Issue(1)：1-16,16.DOI:10.3969/j.issn.1672-9854.2024.01.001
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
摘要
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分类
能源科技引用本文复制引用
张建勇,许强,曹雨,熊绍云,刘思琪,谈轩宇,谭秀成..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[J].海相油气地质,2024,29(1):1-16,16.基金项目
本文受中国石油"十四五"前瞻性基础性重大科技项目"羌塘盆地构造沉积演化与基本石油地质条件研究"(编号:2021DJ0801)和自然科学基金项目"林周盆地从海到山:对冈底斯俯冲-碰撞隆升过程的制约"(编号:42272257)、"羌塘盆地侏罗纪成盐环境与盐构造演化及油气赋存效应"(编号:42241202)和"探寻班公湖—怒江洋南向俯冲弧-沟体系中'缺失'的沉积记录"(编号:42272237)的联合资助 （编号:2021DJ0801）
