柴北缘超高压变质带:从大洋到大陆的深俯冲过程

摘要

The North Qaidam UHPM belt is a typical continental type subduction zone. Coesite inclusions were found from eclogite and country gneiss, and diamond inclusion from garnet peridotite. This paper is focused on the progress of petrology, thermobarometry, geochemistry and geochronology studies of Yuka, Luliangshan, Xitieshan and Dulan terrenes in the North Qaidam UHPM belt. This belt is unique because subducted oceanic relics prior to the continental subduction and collision are well preserved, Combined with the published data, especially the two protolith sources for eclogites, we conclude that the North Qaidam UHPM belt experienced a tectonic evolution from an oceanic subduction to a continental collision.%柴北缘超高压变质带同我国大别-苏鲁造山带类似,同属典型的大陆型俯冲碰撞带.柯石英在榴辉岩和片麻岩中均有发现,且石榴橄榄岩锆石中含有金刚石.本文从岩石学、温压计算、地球化学和年代学四个方面,对此带中的鱼卡、绿梁山、锡铁山和都兰4个榴辉岩和石榴橄榄岩出露地区近些年的研究进展进行了系统详细的综述.与典型的大陆型俯冲碰撞带不同,柴北缘超高压变质带保存了早期陆壳俯冲前发生的洋壳深俯冲的证据.因此,结合现有数据,本文对柴北缘超高压变质带从大洋俯冲到大陆俯冲碰撞的构造演化模式进行了探讨.