摘要:
雅鲁藏布江缝合带是青藏高原上重要的缝合带之一,位于青藏高原南部,蛇绿岩是该带的主体。雅鲁藏布江缝合带按蛇绿岩的出露规模、岩石层序以及侵位时间,大致可以分为东段、中段和西段。在蛇绿岩出露规模上存在显著差异,东段规模较小,中段次之,西段最大,并且在西段分成两支蛇绿岩带;蛇绿岩岩石层序出露比较齐全的是中段日喀则和东段罗布莎,其他地方的蛇绿岩均被肢解,不能组成完整的蛇绿岩岩石剖面;在蛇绿岩的形成和侵位时间上,也有着不同的特点,东段和西段集中形成于晚侏罗世—早白垩世,而中段形成时间较早,时代从中三叠世一直持续到早白垩世,主要集中形成于晚侏罗世—早白垩世。笔者系统研究雅鲁藏布江缝合带蛇绿岩在东西方向上所表现出来的差异性,对更全面深刻地了解新特提斯洋的产生、俯冲及其消亡过程和演化历史具有重要意义。
Abstract:
The Brahmaputra Suture Zone is one of the important suture zones in the Qinghai-Xizang Plateau,located in the southern Qinghai-Xizang Plateau,and the ophiolite is its main body.According to the outcropped size,the lithologic sequence and emplacement time of ophiolite,the Brahmaputra Suture Zone is divided into eastern,middle,and western segments approximately.There exist some differences in the size of ophiolites.The western segment is divided into two ophiolites zones and has the largest size,followed by the middle segment and the eastern segment.There are relatively complete lithologic sequence of ophiolite in the Shigatse of middle segment and Luobusha of eastern segment,but there is not any complete rock profile because of no ophiolites except for Shigatse and Luobusha.In addition,there exist also a difference in the ophiolites formation and emplacement.The eastern,western,and middle segment was formed mainly in the Late Jurassic-Early Cretaceous,but the middle segment was formed is earlier than the other two segments,from Middle Triassic to Early Cretaceous.
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