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喜马拉雅造山带北缘的大反转逆冲断层(GCT)位于印度-亚洲的碰撞边界,平行雅鲁藏布江缝合带展布,向北逆冲使特提斯喜马拉雅地体向北叠覆在冈底斯地体之上。大反转逆冲断裂制约了中新世Kailas式系列磨拉石盆地(Kailas、秋乌、大竹曲、罗布莎以及朗县)的发育,自西向东磨拉石盆地中砾石变形逐渐增强。本文通过GCT东段“罗布莎-郎县砾岩”的研究,获得罗布莎-朗县变形砾岩中的碎屑锆石的沉积上限年龄为早渐新世(28.7~29.1Ma)。罗布莎-郎县砾岩具有基质糜棱岩化、发育地震化石假熔岩和向北剪切指向的特征,表明其经历了受GCT断裂控制的砾岩盆地在浅部形成、插入10~15km深部并受地震影响形成假熔岩,然后折返到地表的过程。
The Great Reversible Thrust (GCT) at the northern margin of the Himalayan orogenic belt lies on the India-Asia collision boundary and is distributed parallel to the Yarlung Zangbo suture zone. The northward thrust causes the Tethyan Himalayan terrane to overlie the Gangtides Above the body. Large-reversal thrust faults have restricted the development of the Kailas-type molasse basin (Kailas, Qiuwu, Dazhuqu, Luobusha and Longxian), and the gravel deformation gradually increases from the west to the eastern Morat basin. In this paper, the upper limit age of detrital zircons in the Luobusha-Langxian conglomerate was Early Oligocene (28.7 ~ 29.1Ma) through the study of the eastern part of the GCT “Lozha-Langxian conglomerate”. The Luobusha-Langxian conglomerate has matrix mylonitization, development of seismic fossil fissure and shear-northward characterization, indicating that it experienced the formation of shallow conglomerate basins controlled by GCT faults and was inserted into the depths of 10-15 km And affected by the earthquake to form false lava, and then returned to the surface of the process.