Cooke, DR and Hollings, P and Wilkinson, JJ and Tosdal, RM, Geochemistry of Porphyry Deposits, Treatise on Geochemistry, Elsevier, H Holland, K Turekian (ed), Italy, pp. 357-381. ISBN 978-0-08-098300-4 (2014) [Research Book Chapter]
Copyright 2014 Elsevier Ltd.
Porphyry ore deposits typically form in convergent plate margin or postsubduction settings at depths of 1-6 km. Oxidized hydrous melts derived from the metasomatized mantle wedge transport Cu, Au, Mo, and other metals to upper-crustal magma chambers. Ponding and release of these magmas is promoted by transient compressional events that perturb steady-state subduction processes, such as the subduction of aseismic ridges or oceanic plateaus. Fractional crystallization leads to repeated cycles of volatile exsolution, vein stockwork formation, and hydrothermal brecciation within and above the mineralizing intrusions. Radiometric dating provides evidence for multiple mineralizing episodes over several million years in some deposits and durations of less than a few hundred thousand years for magmatism and mineralization in others.
Metals are transported by high-temperature brines, vapors, or vapor-like supercritical fluids, depending on local confining pressures. Ore deposition may occur due to decreasing temperature, decreasing pressure, sulfate reduction, water-rock interaction, SO2(g) disproportionation, condensation, or combinations thereof. Stable isotopic data indicate a predominance of magmatically derived sulfur, oxygen, deuterium, copper, iron, and molybdenum in the mineralized core of many porphyry deposits. Lead isotopes provide insights into crustal assimilation processes where there are significant differences in the isotopic compositions of local crustal and mantle sources of Pb.
|Item Type:||Research Book Chapter|
|Keywords:||fluid inclusions, isotopes, magmatic-hydrothermal, porphyry, tectonics, copper, gold, molybdenum, geochemistry|
|Research Division:||Earth Sciences|
|Research Field:||Ore Deposit Petrology|
|Objective Division:||Mineral Resources (excl. Energy Resources)|
|Objective Group:||Mineral Exploration|
|Objective Field:||Copper Ore Exploration|
|UTAS Author:||Cooke, DR (Professor David Cooke)|
|UTAS Author:||Wilkinson, JJ (Professor Jamie Wilkinson)|
|Funding Support:||Australian Research Council (CE0561595)|
|Deposited By:||Centre for Ore Deposit Research - CODES CoE|
|Downloads:||2 View Download Statistics|
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