Skip Navigation


Journal of Petrology Advance Access originally published online on September 7, 2006
Journal of Petrology 2006 47(10):2021-2046; doi:10.1093/petrology/egl035
This Article
Right arrow Full Text Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow All Versions of this Article:
47/10/2021    most recent
egl035v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Search for citing articles in:
ISI Web of Science (5)
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by AUDÉTAT, A.
Right arrow Articles by PETTKE, T.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

© The Author 2006. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oxfordjournals.org

Evolution of a Porphyry-Cu Mineralized Magma System at Santa Rita, New Mexico (USA)

A. AUDÉTAT1,* and T. PETTKE2,{dagger}

1 BAYERISCHES GEOINSTITUT, UNIVERSITÄT BAYREUTH 95440 BAYREUTH, GERMANY
2 INSTITUTE OF ISOTOPE GEOCHEMISTRY AND MINERAL RESOURCES ETH ZENTRUM NO, 8092 ZüRICH, SWITZERLAND

RECEIVED JUNE 30, 2005; ACCEPTED JUNE 12, 2006

The magmatic processes leading to porphyry-Cu mineralization at Santa Rita are reconstructed on the basis of petrographic studies, thermobarometry, and laser-ablation inductively-coupled-plasma mass-spectrometry analyses of silicate melt and sulfide inclusions from dikes ranging from basaltic andesite to rhyodacite. Combined results suggest that magma evolution at Santa Rita is similar to that of sulfur-rich volcanoes situated above subduction zones, being characterized by repeated injection of hot, mafic magma into an anhydrite-bearing magma chamber of rhyodacitic composition. The most mafic end-member identified at Santa Rita is a shoshonitic basaltic andesite that crystallized at 1000–1050°C, 1–3 kbar and log fO2 = NNO + 0·7 to NNO + 1·0, whereas the rhyodacite crystallized at 730–760°C and log fO2 = NNO + 1·3 to NNO + 1·9. Mixing between the two magmas caused precipitation of 0·1–0·2 wt % magmatic sulfides and an associated decrease in the Cu content of the silicate melt from 300–500 ppm to less than 20 ppm. Quantitative modeling suggests that temporal storage of ore-metals in magmatic sulfides does not significantly enhance the amount of copper ultimately available to ore-forming hydrothermal fluids. Magmatic sulfides are therefore not vital to the formation of porphyry-Cu deposits, unless a mechanism is required that holds back ore-forming metals until late in the evolution of the volcanic–plutonic system.

KEY WORDS: porphyry-Cu; sulfur; sulfides; magma mixing; LA-ICP-MS

*Corresponding author. E-mail: andreas.audetat{at}uni-bayreuth.de


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?


This article has been cited by other articles:


Home page
 Economic GeologyHome page
A. Audetat, T. Pettke, C. A. Heinrich, and R. J. Bodnar
Special Paper: The Composition of Magmatic-Hydrothermal Fluids in Barren and Mineralized Intrusions
Economic Geology, August 1, 2008; 103(5): 877 - 908.
[Abstract] [Full Text] [PDF]


Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.