新疆北天山巴音沟蛇绿岩的地质特征

巴音沟蛇绿岩虽受强热构造作用肢解,但仍保存有较完整的蛇纹石化超基性岩、状层辉长岩、基性熔岩(下部块状、上部枕状)和放射虫硅质岩的层序组合。岩石化学、地球化学、放射虫等古生物资料表明,它代表一个中石炭世陆缘海盆迅速扩张形成的洋壳和上地幔的残片。其侵位发生在中石炭世未海盆的封闭期间。

GEOLOGICAL FEATURES OF BAYINGOL OPHIOLITIC SUITE OF NORTH TIANSHAN, XINJIANG

Whether there are ophiolites in Tianshan Mt. of China has been an important problem for many years. A complete sequence of ophiolite was found in Bayingol of North Tianshan in 1983. This has provided a new clue for studying tectonics and looking for related mineral resources in this area. The ophiolites consist, from the lower to the upper, ef serpentized ultrabasic rocks, layered gabbros, basic lavas(including lower massive lavas and upper pillow lavas), and radiolaria cherts overlain by turbidites of the Middle Carboniferous. Typical dike swarm has not been found. The contact between all these units of the ophiolites is fault.Primary sequences have structurally been distroyed. Geological setting, petrol-chemistry and geochemistry of these rocks differ from those of the ophiolites of both Oman and Xigaze (Shigatse), but are very similar to those of west Junggar. Bayingol ophiolites represent the oceanic crust which formed in a rapidly spreading epicontinental sea-basin in the middle Carboniferus, emplaced in the end of the middle Carboniferus.