利用沉积记录精确约束印度-亚洲大陆碰撞时间与过程

发布时间：2018-12-27 07:32

【摘要】：精确约束印度-亚洲初始碰撞时间对于认识喜马拉雅造山过程、青藏高原隆升机制及其对环境、气候和生物的效应具有重要的意义.本文基于对西藏雅鲁藏布缝合带两侧沉积记录的研究,对印度-亚洲大陆初始碰撞时间研究进行了总结和评述,探讨了印度-亚洲大陆初始碰撞的穿时性,重建了大陆碰撞的沉积演化.在接受以大陆间洋壳消失、陆壳-陆壳初始接触作为初始碰撞定义的前提下,利用两种方法:(1)缝合带附近深水浊积岩物源区由印度物源向亚洲物源转变的时间,(2)喜马拉雅欠充填前陆盆地启动在缝合带两侧造成的沉积环境突变或不整合的时间,精确限定印度-亚洲大陆初始碰撞时间为古新世中期((5 9±1)Ma).从喜马拉雅造山带来看,真正的初始碰撞时间比正常海相沉积结束要早20~25Ma,而磨拉石出现比初始碰撞要晚30~40Ma.基于特提斯喜马拉雅古近系沉积记录,印度-亚洲大陆初始碰撞在喜马拉雅中部和西部不存在明显的穿时性.本文从喜马拉雅地区的沉积记录角度出发,将喜马拉雅造山作用划分为四个阶段:(1)始喜马拉雅初始阶段,古新世中期-早始新世(59~52Ma),初始碰撞发生,同碰撞盆地存在深海环境,印度大陆一侧发育碳酸盐缓坡;(2)始喜马拉雅早期阶段,始新世早-中期(52~41Ma或35Ma),以发育残留的浅海沉积为特征,新特提斯海湾自西向东逐渐消亡;(3)始喜马拉雅晚期阶段,始新世末期-渐新世(41~26Ma),整个喜马拉雅和藏南地区缺乏沉积作用;(4)新喜马拉雅早期阶段,渐新世末期-早中新世(2 6~17Ma),喜马拉雅隆升,陆相磨拉石快速堆积,沿缝合带东西向发育雅鲁藏布江和印度斯河.
[Abstract]:The precise constraint of the initial collision time between India and Asia is of great significance in understanding the Himalayan orogenic process, the uplift mechanism of the Qinghai-Tibet Plateau and its environmental, climatic and biological effects. Based on the study of sedimentary records on the two sides of the Yalu Tibetan suture belt in Tibet, this paper summarizes and reviews the study of the initial collision time of the Indo-Asian continent, and probes into the transitability of the initial collision between the Indian and Asian continents. The sedimentary evolution of continental collision was reconstructed. Under the assumption that the inter-continental oceanic crust disappears and the initial continental crust-crust contact is taken as the definition of initial collision, two methods are used: (1) the time of the transition from Indian source to Asian source of deep-water turbidite source near the suture zone. (2) the time of abrupt change or unconformity of sedimentary environment caused by the initiation of Himalayan underfilled Foreland basin on both sides of the suture zone, which accurately limits the initial collision time of Indo-Asian continent to the middle Paleocene (5.9 卤1) Ma). From the Himalayan orogenic belt, the real initial collision time is 20 ~ 25 Ma earlier than the end of the normal marine deposit, while the Molar rock appears 30 ~ 40 Ma. later than the initial collision. Based on the sedimentary records of the Tethys Himalayan Paleogene the initial collision between India and Asia has no obvious transversal time in the central and western Himalayas. The Himalayan orogeny is divided into four stages from the perspective of sedimentary records in the Himalayan region: (1) the initial Himalayan stage, the middle Paleocene to early Eocene (59~52Ma), and the initial collision. There is a deep-sea environment in the syncollision basin and carbonate gentle slope is developed on the Indian continental side. (2) in the early stage of the early Himalayas, the early Eocene period (52~41Ma or 35Ma) was characterized by residual shallow sea deposits, and the NeoTethys Bay gradually disappeared from west to east; (3) the late stage of the early Himalayas, the late Eocene to the Oligocene (41~26Ma), and the lack of sedimentation in the whole Himalayan and southern Tibet regions; (4) in the early stage of the Neo-Himalayas, the late Oligocene to the early Miocene (2 6~17Ma), the Himalayan uplift, the rapid accumulation of continental molars, and the development of the Yarlung Zangbo River and the Indian River along the east-west direction of the suture zone.
【作者单位】：南京大学内生金属矿床成矿机制研究国家重点实验室南京大学地球科学与工程学院;中国科学院地质与地球物理研究所;合肥工业大学资源与环境工程学院;Department
【基金】：国家自然科学基金杰出青年基金项目(编号:41525007) 中国科学院战略性先导科技专项(B类)项目(编号:XDB03010400)资助
【分类号】：P542

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