Geochemical differences between subduction- and collision-related copper-bearing porphyries and implications for metallogenesis

Chen, JianLin, Xu, JiFeng, Wang, BaoDi, Yang, ZhiMing, Ren, JiangBo, Yu, HongXia, Liu, Hongfei and Feng, Yuexing (2015) Geochemical differences between subduction- and collision-related copper-bearing porphyries and implications for metallogenesis. Ore Geology Reviews, 70 424-437. doi:10.1016/j.oregeorev.2015.01.011

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Author Chen, JianLin
Xu, JiFeng
Wang, BaoDi
Yang, ZhiMing
Ren, JiangBo
Yu, HongXia
Liu, Hongfei
Feng, Yuexing
Title Geochemical differences between subduction- and collision-related copper-bearing porphyries and implications for metallogenesis
Journal name Ore Geology Reviews   Check publisher's open access policy
ISSN 0169-1368
1872-7360
Publication date 2015-10
Year available 2015
Sub-type Article (original research)
DOI 10.1016/j.oregeorev.2015.01.011
Open Access Status File (Author Post-print)
Volume 70
Start page 424
End page 437
Total pages 14
Place of publication Amsterdam, Netherlands
Publisher Elsevier
Collection year 2016
Language eng
Formatted abstract
Porphyry Cu (–Mo–Au) deposits occur not only in continental margin–arc settings (subduction-related porphyry Cu deposits, such as those along the eastern Pacific Rim (EPRIM)), but also in continent–continent collisional orogenic belts (collision-related porphyry Cu deposits, such as those in southern Tibet). These Cu-mineralized porphyries, which develop in contrasting tectonic settings, are characterized by some different trace element (e.g., Th, and Y) concentrations and their ratios (e.g., Sr/Y, and La/Yb), suggesting that their source magmas probably developed by different processes. Subduction-related porphyry Cu mineralization on the EPRIM is associated with intermediate to felsic calc-alkaline magmas derived from primitive basaltic magmas that pooled beneath the lower crust and underwent melting, assimilation, storage, and homogenization (MASH), whereas K-enriched collision-related porphyry Cu mineralization was associated with underplating of subduction-modified basaltic materials beneath the lower crust (with subsequent transformation into amphibolites and eclogite amphibolites), and resulted from partial melting of the newly formed thickened lower crust. These different processes led to the collision-related porphyry Cu deposits associated with adakitic magmas enriched by the addition of melts, and the subduction-related porphyry Cu deposits associated with magmas comprising all compositions between normal arc rocks and adakitic rocks, all of which were associated with fluid-dominated enrichment process.

In subduction-related Cu porphyry magmas, the oxidation state (fO2), the concentrations of chalcophile metals, and other volatiles (e.g., S and Cl), and the abundance of water were directly controlled by the composition of the primary arc basaltic magma. In contrast, the high Cu concentrations and fO2 values of collision-related Cu porphyry magmas were indirectly derived from subduction modified magmas, and the large amount of water and other volatiles in these magmas were controlled in part by partial melting of amphibolite derived from arc basalts that were underplated beneath the lower crust, and in part by the contribution from the rising potassic and ultrapotassic magmas. Both subduction- and collision-related porphyries are enriched in potassium, and were associated with crustal thickening. Their high K2O contents were primarily as a result of the inheritance of enriched mantle components and/or mixing with contemporaneous ultrapotassic magmas.
Keyword Geochemistry
Subduction- and collision-related
Cu-bearing porphyry
Eastern Pacific Rim
Southern Tibet
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Earth Sciences Papers
Official 2016 Collection
 
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Created: Tue, 23 Jun 2015, 01:44:34 EST by System User on behalf of School of Earth Sciences