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

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.