Zircon U-Pb Ages of Dongcuo Ophiolite in Western Bangonghu-Nuj iang Suture Zone and Their Geological Significance
Wu Yong
Chen Songyong
Qin Mingkuan
Guo Dongfa
Guo Guolin
Zhang Cai
Yang Jingsui
Abstract：The Dongcuo ophiolite is located at the western part of Bangong-Nujiang River suture zone,Gaize County.In spite of previous studies on its spacious distribution,tectonic environment and genesis,the key problem remains unresolved.Taking the gabbro of Dongcuo ophiolite as the research object,a detailed study of petrography,geochemistry,petrology and geochro-nology is carried out to understand the formation of Bangong-Nujiang ocean basin,the tectonic settings of the Dongcuo ophio-lite.Compared with N-MORB,the major and trace elements of Dongcuo ophiolite are characterized by high content in Mg#and low content in K,Na,P,and Ti,the depletion of high field-strength elements(HFSE)of Hf,Zr,Nb and light rare earth element depletion.Geochemistry characteristics of the Dongcuo ophiolite indicate that it is originated from ~30% partial melt-ing of depleted spinel lherzolite formed in the tectonic environment of subduction-related island arc or fore arc,belonging to super subduction zone(SSZ)ophiolite.The LA-ICP-MS of zircon U-Pb dating yields the age of 222±4.8 Ma(MSWD=0.5), providing the age constraint on the Dongcuo ophiolite(Late Triassic),and showing that it belongs to the Tethyan system of the Bangong-Nujiang River suture zone,which indicates the intra-oceanic subduction process.
Keywords：ophiolitegabbrotectonic environmentzircon U-Pb datingBangong-Nujiang suture zonegeochronology
Publication Date：2018-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：15( 1070-1084 )