Collision-related porphyry Cu deposits formed by input of ultrapotassic melts into the sulfide-rich lower crust

Yuan-Chuan Zheng*, Yang Shen, Lu Wang, William L. Griffin, Zeng-Qian Hou

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)

Abstract

Collision-related porphyry Cu deposits (PCDs) are restricted to previous magmatic arcs, in which sulfide-rich lower crust occurred. Fertile adakite-like porphyries associated with PCDs have higher K2O contents and K2O/Na2O ratios than barren porphyries emplaced in the same arc. The elevated K2O/Na2O ratios of fertile porphyries reflect substantial inputs of coeval hydrous, oxidized ultrapotassic melts. Input of such melts could increase the water content and oxygen fugacity of the lower-crust-derived melts, which in turn would promote the breakdown of sulphides in the lower crust and increase the contents of Cu and S in the melts, making them favourable for the formation of large PCDs. The relatively low K2O contents and K2O/Na2O ratios of barren porphyries indicate limited input of ultrapotassic melts; these magmas have low potential to form PCDs. Thus, the input of ultrapotassic melts into the sulfide-rich juvenile lower crust drives the formation of collision-related PCDs.

Original languageEnglish
Pages (from-to)582-589
Number of pages8
JournalTerra Nova
Volume33
Issue number6
DOIs
Publication statusPublished - Dec 2021

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