中国西北地区蛇绿岩时空分布与构造演化

Spatial and temporal distribution of ophiolites and regional tectonic evolution in Northwest China

西北地区蛇绿岩广泛分布在天山、秦祁昆等造山带和塔里木、准噶尔等陆块周缘,构成一幅浑然天成的陆块-混杂带交织图,演绎着漫长的地质演化历史。在近年来小比例尺西北地质图编制的基础上,系统收集整理了区内有关蛇绿岩的资料文献,梳理了西北蛇绿混杂岩的空间分布与时间序列,重点叙述了西北地区蛇绿混杂岩特征,探讨西北地区蛇绿岩时空分布与地质构造演化的关系。西北地区36条蛇绿混杂岩带是蛇绿岩的赋存空间,可以划归为5个区、2个对接带和2个缝合带。红柳沟-北祁连山新太古代—中元古代蛇绿岩可能与地壳早期演化有关,柯坪、勉略、松树沟等新元古代早期蛇绿岩与Rodinia超大陆的裂解和局部洋陆转化相关,大量古生代以来的蛇绿岩是古亚洲和特提斯两大构造域多陆块岛弧洋盆系统洋陆转化作用的记录。

Ophiolites are widely spread in such orogenic belts as Tianshan,Qilian,Kunlun and Qinling mountains as well as on such continental margins as Tarim and Junggar,which show an intersection map of continent-ophiolite and the geological evolution history of Northwest China.On the basis of geological mapping at the small scale conducted during the recent years,the authors systematically compiled geological information about ophiolites in Northwest China,summarized the spatial distribution and temporal series,focused geological features of ophiolite melanged,and preliminarily discussed the relationship between ophiolites and tectonic evolution.There are 36 ophiolite mealange belts which could be divided into 5 tectonic blocks,2 convergent crustal consumption zones and 2 suture zones in Northwest China.Ophiolites of Neo-Archean to Meso-Proterozoic period in Altay and north Qilian mountains might have been related to crust evolution of early stages.Early Neo-Proterozoic ohpiolites such as Keping,Mianlue and Songshugou ohpiolites probably resulted from the breakup of Rodinia and local ocean-land transformation.Large quantities of ophiolites since Paleozoic are records of ocean-continent conversion of the Paleo-Asian Ocean and Proto-Tethys to Paleo-Tethys in Northwest China.