摘要
The ophiolitic mélange and mafic granulites are outcropped in the Weiya segment which is near to the northern boundary fault of the Central Tianshan belt. The petrological and geochemical data suggest that the geochemical features of the diabase and gabbro of the ophiolitic mélange are similar, characterized by high MgO contents (6.78%), low Na2O+K2O (0.52%) contents and Na2O > K2O. Combining with previous research results on the regional geology, petrology and geochemistry, the authors conclude that the mafic-ultramafic blocks in the eastern Weiya belong to the dismembered EMORB-type ophiolite, formed in mid-oceanic ridge and represents fragments of ancient Tianshan oceanic basin. The protolith of mafic granulites was formed in an immature island-arc setting. The ophiolitic melange and mafic granulites may be related to the subduction of oceanic plate along the northern boundary fault of the Central Tianshan and represents the relics of the Tianshan Ocean.