Chronology,Geochemistry and Tectonic Significance of Daba Ophiolites in Western Segment of Yarlung Zangbo Suture Zone,Tibet
Cheng Chen
Xia Bin
Zheng Hao
Yuan Yajuan
Yin Zhengxin
Lu Ye
Xu Chi
Zhang Xiao
Abstract：The Daba ophiolite is located in the southern sub-belt of the western segment of the Yarlung Zangbo suture zone (YZSZ)and mainly composed of mantle peridotite,mafic dikes and siliceous rocks.Its formation time and tectonic setting are not clear.This is the first report of zircon U-Pb age,petrologic and whole-rock geochemical data from the Daba ophiolite.The major elements of Daba gabbro and dolerite are characterized by high contents in Al,Mg and low contents in Ti,K and P, which belong to subalkaline basalt.The REE distribution patterns are very similar to those of the normal mid-ocean ridge basalt (N-MORB).However,the normalized spider diagram shows significant depletion of Nb,suggesting the influence of fluids from downgoing slab.The dolerites yielded zircon U-Pb ages of 120.0±1.7 Ma,and geochemical features show partial melting from the low degree spinel-bearing mantle source.Combining with previous studies,it is suggested that the intrusion of the mafic rocks into the Daba peridotites may be interpreted as a result of mixing process between MORB-like melts and arc-derived fluids,which may have occurred during the stage of subduction initiation in an extending forearc region.
Keywords：Yarlung Zangbo suture zoneDaba ophiolitegeochemistryzircon U-Pb agetectonic setting
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：16( 975-990 )