西藏松多古特提斯洋研究进展与存在问题

The research progress and problem of the Sumdo Paleo-Tethys Ocean,Tibet

青藏高原古特提斯构造域的演化过程一直是国内外地学研究关注的前沿和热点,冈底斯中部松多地区因榴辉岩带的发现,使其成为近年来国内外研究者关注的焦点地区之一。为了更好认识青藏高原古特提斯洋的构造演化历史,本文在综述前人研究的基础上,系统地总结了近年来1∶5万区域地质调查中取得的最新研究进展,初步讨论了唐加-松多地区俯冲增生杂岩带的物质组成和时代。研究表明,西藏冈底斯中部唐加-松多地区保存了相对完整的与古特提斯洋演化以及洋陆转换密切相关的混杂岩,是恢复和反演古特提斯洋演化的理想靶区。松多古特提斯洋洋壳及其消亡的地质记录主要包括晚古生代唐加-松多蛇绿岩、中二叠世洋岛残片、高压变质带、晚三叠世—早侏罗世岩浆作用以及晚三叠世—早侏罗世磨拉石建造。在上述工作基础上,初步探讨了松多古特提斯洋的演化过程,这些地质记录对恢复和反演青藏高原古特提斯构造演化研究具有重要意义。

The evolution process of the Paleo-Tethys tectonic domain on the Qinghai-Tibet plateau has always been a frontier and hotspot of geological research.In order to better understand the tectonic evolution history of the Paleo-Tethys ocean on the Qinghai-Tibet plateau,based on the previous studies,this paper systematically summarized the latest research progress made in recent years in the 1:50,000 regional geological survey,and preliminarily discussed the material composition and the age of subduction and actinic complex zone in the Tangjia-Sundo area.The results show that relatively complete mélange closely related to the evolution of the Paleo-Tethys ocean and the transition of ocean and land are preserved in the Tangjia-Sumdo area in central Gangdise,Tibet,which is an ideal target area for recovery and inversion of the evolution of the Paleo-Tethys ocean.The geological records of the Sumdo Paleo-Tethys crust and its extinction mainly include the late Paleozoic Tangjia-Sumdo ophiolite mélange belt,middle Permian ocean island fragments,high pressure metamorphic belt,late Triassic-early Jurassic magmatism and late Triassic-early Jurassic molassite formation.On the basis of the above work,the evolution process of the Sumdo Paleo-Tethys is preliminarily discussed.These geological records are of great significance to the recovery and inversion of the Paleo-Tethys tectonic evolution on the Qinghai-Tibet plateau.