Permian Volcanic Rocks in the Bayan Hala Turbidite Basin, East Kunlun Area

Permian volcanic rocks are developed in fault nip blocks of the Zanayi-Geqiongniwa and Yueguzonglie fault zones in the Bayan Hala turbidite basin, east Kunlun area. Volcanic rocks are output in tectonic slices. The volcanic rock assemblage in the Zanayi-Geqiongniwa fault zone is mainly basalts and basaltic andesites, some with the pillow structure. The SiO₂ content of the volcanic rocks is uniform, the TiO₂ content is higher and the ALK content is lower. The rock type is mainly tholeiitic basalt. REE distribution patterns of which are LREE-rich type and consistent with those of ocean island type volcanic rocks, the large ion lithophile elements of volcanic rocks is more enrichment, HFS elements and HREE of them is flatten. The characteristics of REE, trace elements and tectonic setting distinguishing reveal that the volcanic rocks of the Zanayi-Geqiongniwa fault belt were formed mainly in an ocean island tectonic setting, while some were formed in a middle ocean ridge tectonic setting. The volcanic rock assemblage in the Yueguzonglie fault zone consists of basalt and basaltic andesite. Their SiO₂ content is higher, while TiO₂ content is less than one percent. The rock types are calc-alkaline series. REE distribution patterns of basaltic andesite are consistent with that of the volcanic rocks in the Zanayi-Geqiongniwa fault zones, that of dacite is high rich in LREE and consistent with island arc high-K andesite. Tectonic setting distinguishing reveals that the volcanic rocks of the Yueguzonglie fault belt are formed in island arc tectonic setting. According to the differing contents of the volcanic rocks and clast from the Bayan Hala Group beside the Zanayi-Geqiongniwa fault belt, we can divide the Bayan Hala turbidite basin into north subbelt and south subbelt.