Geologic and tectonic evolution of the Himalaya before and after the India-Asia collision
Geologic and tectonic evolution of the Himalaya before and after the India-Asia collision
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印度-亚洲碰撞前后喜马拉雅山的地质和构造演化
DOI：
10.1007/bf02841594
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
K. K. Sharma
中科院分区：
文献类型：
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作者：
K. K. Sharma
本文根据作者的新资料和最近的研究，对喜马拉雅山的地质构造作了评述。这些资料表明，小喜马拉雅片麻质基底（LHGB）代表了北方印度地盾本德尔坎德克拉通的北方延伸，并在古元古代王土造山运动末期，在LHGB中发生了大规模的花岗岩岩浆活动，在2 - 1.9Ga之间稳定了该地区的早期地壳。该区经历了小喜马拉雅裂谷盆地的快速隆升和发展，其中在古元古代和中元古代继续进行旋回沉积。特提斯盆地及其底部的Vaikrita岩石被认为是一个年轻的裂谷盆地（约900 Ma前），位于小喜马拉雅盆地的北部，被LHGB所包围。小喜马拉雅盆地的南移，以Jaunsar-Simla旋回和Blaini-Krol-Tal旋回在封闭盆地中的沉积为标志，特提斯盆地在晚前寒武纪-寒武纪期间沉积格局的变化，变形和大规模的花岗岩活动（约500 ± 50Ma），表明喜马拉雅地区存在晚前寒武纪-寒武纪Kinnar Kailas造山运动的可能性很大。从新特提斯洋壳的俯冲、弧生长和碰撞的记录来看，喜马拉雅地区自元古代以来一直在逐渐增长，沉积中心在南北向的挤压和伸展交替作用下向北移动。在喜马拉雅碰撞情景中，被夹在印度板块俯冲陆壳和新特提斯洋壳向南逆冲推覆作用与印度-唐坡碰撞带弧形成分之间的10 - 12km厚的特提斯盆地松散沉积堆（TSS），由于大规模的褶皱和层内逆冲作用而显著增厚，并随着克什米尔逆冲断层席沿着潘加尔逆冲断层向南移动。这就导致了下伏Vaikrita岩石的早期阶段（M1）Barrovian型变质作用。随着印度板块的持续向北推进，Vaikrita岩石遭受了最大的压缩，变形和再活化，并在渐新世-中新世期间迅速作为高喜马拉雅结晶（HHC）折返，导致特提斯沉积盖层的重力滑动。在INDEPTH剖面上，LHGB的陆壳向喜马拉雅山和藏南俯冲，其盖层岩以逆冲岩片叠加形成喜马拉雅山，其滑脱面反映为主喜马拉雅逆冲断层（MHT）。
The geology and tectonics of the Himalaya has been reviewed in the light of new data and recent studies by the author. The data suggest that the Lesser Himalayan Gneissic Basement (LHGB) represents the northern extension of the Bundelkhand craton, Northern Indian shield and the large scale granite magmatism in the LHGB towards the end of the Palæoproterozoic Wangtu Orogeny, stabilized the early crust in this region between 2-1.9 Ga. The region witnessed rapid uplift and development of the Lesser Himalayan rift basin, wherein the cyclic sedimentation continued during the Palæoproterozoic and Mesoproterozoic. The Tethys basin with the Vaikrita rocks at its base is suggested to have developed as a younger rift basin (∼ 900 Ma ago) to the north of the Lesser Himalayan basin, floored by the LHGB. The southward shifting of the Lesser Himalayan basin marked by the deposition of Jaunsar-Simla and Blaini-Krol-Tal cycles in a confined basin, the changes in the sedimentation pattern in the Tethys basin during late Precambrian-Cambrian, deformation and the large scale granite activity (∼ 500 ± 50 Ma), suggests a strong possibility of late Precambrian-Cambrian Kinnar Kailas Orogeny in the Himalaya. From the records of the oceanic crust of the Neo-Tethys basin, subduction, arc growth and collision, well documented from the Indus-Tsangpo suture zone north of the Tethys basin, it is evident that the Himalayan region has been growing gradually since Proterozoic, with a northward shift of the depocentre induced by N-S directed alternating compression and extension. During the Himalayan collision scenario, the 10–12km thick unconsolidated sedimentary pile of the Tethys basin (TSS), trapped between the subducting continental crust of the Indian plate and the southward thrusting of the oceanic crust of the Neo-Tethys and the arc components of the Indus-Tangpo collision zone, got considerably thickened through large scale folding and intra-formational thrusting, and moved southward as the Kashmir Thrust Sheet along the Panjal Thrust. This brought about early phase (M1) Barrovian type metamorphism of underlying Vaikrita rocks. With the continued northward push of the Indian Plate, the Vaikrita rocks suffered maximum compression, deformation and remobilization, and exhumed rapidly as the Higher Himalayan Crystallines (HHC) during Oligo-Miocene, inducing gravity gliding of its Tethyan sedimentary cover. Further, it is the continental crust of the LHGB that is suggested to have underthrust the Himalaya and southern Tibet, its cover rocks stacked as thrust slices formed the Himalayan mountain and its decollement surface reflected as the Main Himalayan Thrust (MHT), in the INDEPTH profile.