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.