New Discovery of the Diorite Porphyry Dyke in the Shamuluo Formation in Western Segment of the Bangongco—Nujiang Suture Zone and Its Geological Significance
LEI Chuan-yang, WU Jian-liang, YIN Xian-ke, LIU Wen, WANG Bo, LI Wei, YUAN Hua-yun, ZHANG Wei, YIN Tao, PEI Ya-lun
Geological Survey of Sichuan Province, Chengdu 610081, China
Abstract：In order to discuss the genesis and tectonic setting of the diorite porphyry dyke in the Shamuluo Formation in the western segment of the Bangongco-Nujiang suture zone,and to further discuss their significances to the regional tectonic evolution, the chronology and geochemistry of the diorite porphyry dyke have been undertaken in this paper. The results indicate that the diorite porphyry is characterized with features of a metaluminous,high-potassium and calc-alkaline I-type granitoid,with a LA-ICP-MS zircon U-Pb dating age of(103.5±1.5)Ma and the medium differentiation. The chondrite-normalized REE patterns are generally right-declined patterns which are characterized with steep in left and flat in rightand intermediate negative Eu anomalies. The primitive mantle-normalized trace element spider diagrams show that it is relatively enriched in large ion lithophile elements,such as Rb, K,Th, Zr, Hf, U, and is depleted in high field strength element,such as Ba, Nb,P and Ti. With the combination of regional geological background, it is suggested that the diorite porphyry could be formed in the continental arc setting resulted fromof the northward subduction of the Bangongco-Nujiang Tethyan Ocean.The magma was mainly derived from the partial melting of lower crust which was caused by the underplating of the mantle magma derived from the metasomatized mantle wedge by subducted sediments. It is believed that the Bangongco-Nujiang oceanic plate was still northward subducting to the Qiangtang plate in late stage of the early Cretaceous approximately at(103.5±1.5)Ma.
雷传扬, 吴建亮, 尹显科, 刘文, 王波, 李威, 袁华云, 张伟, 尹滔, 裴亚伦. 班公湖-怒江缝合带西段沙木罗组地层中闪长玢岩脉的发现及其地质意义[J]. 矿物岩石地球化学通报, 2018, 37(2): 250-259.
LEI Chuan-yang, WU Jian-liang, YIN Xian-ke, LIU Wen, WANG Bo, LI Wei, YUAN Hua-yun, ZHANG Wei, YIN Tao, PEI Ya-lun. New Discovery of the Diorite Porphyry Dyke in the Shamuluo Formation in Western Segment of the Bangongco—Nujiang Suture Zone and Its Geological Significance. Acta Metallurgica Sinica, 2018, 37(2): 250-259.
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