藏北班公湖—怒江缝合带侏罗纪洋岛型岩石组合——来自岩石学和地球化学的证据

那东洋岛位于班公湖—怒江板块缝合带的中西段,前人已对其进行了初步报道,但未进行详细的研究。对那东洋岛的岩石组合进行岩石学、地球化学的研究,显示那东洋岛具典型的洋岛型岩石组合,其玄武岩和辉长岩的稀土元素配分曲线和微量元素蛛网图与典型OIB相似。通过对洋岛灰岩中珊瑚化石的鉴定,结合洋岛岩石组合与木嘎岗日岩组的野外接触关系,初步认为那东洋岛的时代为中侏罗世,这一时期班公湖—怒江带特提斯洋正处于大洋演化阶段。那东洋岛的发现对揭示班公湖—怒江洋在侏罗纪的演化历史具有重要意义。

Jurassic oceanic island type rock association in the Bangong Co-Nujiang River suture zone: Evidence from petrology and geochemistry

Nadong oceanic island in the middle and western part of the Bangong Co-Nujiang River suture zone has already been preliminarily reported by previous researchers. The authors conducted detailed research on the petrology and geochemistry of Nadong oceanic island, and the results indicate that Nadong oceanic island is a typical oceanic island-type rock association. The basalt and gabbro in the REE patterns and spider diagrams are similar to features of typical OIB. Based on the identification of coral fossils in oceanic limestone and the observation of the contact relationship between the island rock association and the Mugakangri rock group, the authors believe that Nadong oceanic island was formed in the Middle Jurassic. During this period, a Jurassic ocean basin existed in the Bangong Co-Nujiang River suture zone. The discovery of the Nadong oceanic island plays a key role in revealing the evolutionary history of the Bangong Co-Nujiang River Ocean during the Jurassic.