再论西昆仑库地蛇绿岩及其构造意义

A further discussion of the Küda ophiolite,West Kunlun,and its tectonic significance

近年从事西部造山带,特别是西昆仑造山带研究的国内外地质学家,对库地蛇绿岩的发生时限、环境及其构造演化讨论较热烈。原因是:它很可能是中国较早发生的古蛇绿岩之一,涉及青藏高原北缘是否存在“原(古)特提斯(ProterozoicTethys)”大洋以及地质历史早期板块构造演化特征、Rodinia古陆的裂解-聚合等问题,讨论焦点是对该蛇绿岩发生的时限和形成环境的判别、认识问题。本文结合历次对该蛇绿岩的观察,重点就最近该蛇绿岩中石英辉长岩的锆石SHRIMP-Ⅱ测年给出510Ma±4Ma及其构造意义作一简要报道。

In recent years geologists who undertake the study of orogenic belts in western China, especially the West Kunlun orogenic belt, have had a heated discussion of the timing, environment and tectonic evolution of the Küda ophiolite in the West Kunlun. The reason is that it is very likely to be one of the ancient ophiolites that occurred earlier in China and concerns such problems as whether there existed a 'Proterozoic Tethys' ocean on the northern margin of the Qinghai-Tibet Plateau, as well as the characteristics of tectonic evolution of plates in the early stages of the geological history and break-up and convergence of Rodinia. The discussion focuses on the judgment and understanding of the timing and genetic environment of the ophiolite. In combination of previous observations of the ophiolite, this paper mainly reports the recent zircon SHRIMP-II dating of quartz gabbro in the Küda ophiolite (which yields an age of 510Ma±4Ma) and its tectonic significance.