Abstract:
Abstract:Some gneissic granite bodies are exposed in the Lubai Mountain of Hami area, Xinjiang. Zircons from these rocks were dated at (1453±15) Ma by SHRIMP, suggesting that their intrusion occurred in middle Proterozoic. Data of major elements and trace elements show that the gneissic granite bodies are enriched in MgO, FeOt, CaO, depleted in alkaline-earth metals and have low K2O/Na2O ratios. REE partition patterns are inclined to the right. The lithophile elements are obviously concentrated whereas Nb and Ta are depleted relative to MOR granite, suggesting characteristics of I type granite. These data provide important information for the possible geological event of the closure of South Tianshan Ocean in Proterozoic.