Petrogenesis of Yarigong Granodiorite in Batang Area and Constraints on Porphyry Cu Fertility,Eastern Tibetan Plateau
Yang Zongyong
Zhu Jingjing
Pan Lichuan
Huang Mingliang
Wang Dianzhong
Abstract：The Paleo-Tethyan Ocean,represented by the Jinshajiang River suture in eastern Tibetan Plateau,was consumed and closed in the Early-Middle Triassic,but the specific process after the oceanic crust demise is still poorly constrained.The potential for porphyry copper mineralization of magma generated in post-subduction setting remains unclear.In present study,geochronological and geochemical analyses were carried out on the Yarigong pluton in Batang area.Magmas were intruded in Late Triassic as corroborated by zircon U-Pb mean age of about 227 Ma.Rocks from this intrusion were characterized by high SiO2(65.5%to 67.6%)and Mg#(53 to 64),as well as high initial 87Sr/86Sr values(0.709 8 to 0.711 8)and low εNd(t)values(-7.4 to-8.0).Magma generation of the Yarigong pluton resulted from interaction between melts derived from continental crust and peridotite mantle,and partial melts of the continental crust was likely associated with the break-off of early subducted Paleo-Tethyan oceanic slab.Geochemical compositions of amphibole and zircon suggest high magma H2O contents(>5%),the oxygen fugacity of magma is lower than magma related to typical porphyry Cu deposits,and extremely low S in magma was indicated by consistent low SO3 in apatite.These conditions imply barren magma for porphyry Cu deposit formation.
Keywords：high Mg# felsic rockslab break-offporphyry Cu fertilityLate TriassicJingshajiang Paleo-Tethyspetrologymineral exploration
Publication Date：2025-11-30
Online Publishing Date：2025-12-15(First online date of this platform, not the publication date of the document)
Pages：13( 4195-4207 )