冈瓦纳大陆北缘早期的洋壳信息──来自青藏高原羌塘中部早古生代蛇绿岩的依据

Oceanic crust on the northern margin of Gondwana—evidence from Early Paleozoic ophiolite in central Qiangtang, Qinghai-Tibet Plateau.

摘要: 冈瓦纳大陆北缘裂解普遍认为发生在泥盆纪，形成了古特提斯洋并持续演化到晚三叠世。最近在羌塘中部的桃形湖—果干加年山一带发现了完整的蛇绿岩组合，蛇绿岩中的堆晶辉长岩具有洋中脊玄武岩的地球化学特征，在堆晶辉长岩中获得467 Ma～431Ma的锆石SHRIMP U-Pb年龄，这是龙木错-双湖缝合带首次发现早古生代蛇绿岩，应记录了冈瓦纳北缘早期的洋壳演化信息，冈瓦纳大陆北缘的裂解可能发生于早古生代。

Abstract: It is generally considered that the breakoff of the northern margin of Gondwana took in the Devonian forming the Paleo-Tethys, which continued to evolve till the Late Triassic. Recently, a complete ophiolite association has been found in the Taoxinghu-Guoganjianian area, central Qiangtang, SHRIMP U-Pb zircon dating of cumulate gabbro with geochemical characteristics of MORB yielded ages of 467-431 Ma. This is the first found Early Paleozoic ophiolite in the Longmucuo-Shuanghu suture zone and records the information about the early evolution of oceanic crust on the northern margin of Gondwana. The breakoff of the northern margin of Gondwana probably took place in the Early Paleozoic.