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Science 3 September 1993:
Vol. 261. no. 5126, pp. 1282 - 1286
DOI: 10.1126/science.261.5126.1282
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Articles

Rhenium-Osmium Evidence for Regional Mineralization in Southwestern North America

T. E. McCandless 1 and J. Ruiz 1

1 Department of Geosciences, University of Arizona, Tucson, AZ 85721

More than 40 base metal porphyry ore deposits in southwestern North America are associated with the Laramide orogeny (about 90 million to 50 million years ago). Rhenium-osmium dates on molybdenite, a rhenium-enriched sulfide common in many of the deposits, reveal that in individual deposits mineralization occurs near the final stages of magmatic activity irrespective of the time of inception, magnitude, or duration of magmatism. Deposits that differ widely in location and in the extent and timing of magmatism have nearly identical ages for mineralization. Rhenium-osmium-ages suggest that mineralization occurred during two distinct intervals from about 74 million to 70 million years ago and from 60 million to 55 million years ago. Most deposits that formed in the oldest interval are within the older Precambrian basement of northwestern Arizona, whereas the younger deposits are restricted to the younger Precambrian basement in southern Arizona and northern Mexico. Synchronous, widespread mineralization indicates that similar crust-mantle interaction occurred on a regional scale for ore deposits once thought to be the product of localized processes.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
The Role of Bacteria in the Supergene Environment of the Morenci Porphyry Copper Deposit, Greenlee County, Arizona.
M. S. Enders, C. Knickerbocker, S. R. Titley, and G. Southam (2006)
Economic Geology 101, 59-70
   Abstract »    Full Text »    PDF »
Laramide Porphyry Cu-Mo Mineralization in Northern Mexico: Age Constraints from Re-Os Geochronology in Molybdenite.
F. Barra, F. Barra, J. Ruiz, V. A. Valencia, L. Ochoa-Landin, J. T. Chesley, and L. Zurcher (2005)
Economic Geology 100, 1605-1616
   Abstract »    Full Text »    PDF »
Tectono-Magmatic Precursors for Porphyry Cu-(Mo-Au) Deposit Formation.
J. P. Richards and J. P. Richards (2003)
Economic Geology 98, 1515-1533
   Abstract »    Full Text »    PDF »
Age of Mineralization of the Candelaria Fe Oxide Cu-Au Deposit and the Origin of the Chilean Iron Belt, Based on Re-Os Isotopes.
R. Mathur, R. Mathur, R. Marschik, J. Ruiz, F. Munizaga, R. A. Leveille, and W. Martin (2002)
Economic Geology 97, 59-71
   Abstract »    Full Text »    PDF »
Relationship between copper tonnage of Chilean base-metal porphyry deposits and Os isotope ratios.
R. Mathur, J. Ruiz, and F. Munizaga (2000)
Geology 28, 555-558
   Abstract »    Full Text »    PDF »


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Science. ISSN 0036-8075 (print), 1095-9203 (online)