The formation age of ores from the Pebble Cu-Au-Mo giant deposit (Alaska, United States)

Zircons from the porphyry-like quartz-diorite boss of the Pebble Cu-Au-Mo deposit (southwest Alaska) have been examined. By their appearance and internal structure (cathode luminescence and electron probing), the zircons have been subdivided into four genetic groups: (1) xenogenic detrital (mainly r...

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Bibliographic Details
Published in:Doklady earth sciences 2012-02, Vol.442 (2), p.196-201
Main Authors: Kremenetskii, A. A., Popov, V. S., Gromalova, N. A.
Format: Article
Language:English
Subjects:
Age
Bosses
CATHODES
Copper
COPPER RESOURCES
CRYSTAL STRUCTURE
Crystallization
Dating
Deposits
Earth and Environmental Science
Earth Sciences
Geochemistry
Geological time
Geology
Mineralization
Mineralogy
Molybdenum
Porphyry
PORPHYRY ORES
Quartz
Rocks, Metamorphic
Sulfides
Zircon
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Summary:Zircons from the porphyry-like quartz-diorite boss of the Pebble Cu-Au-Mo deposit (southwest Alaska) have been examined. By their appearance and internal structure (cathode luminescence and electron probing), the zircons have been subdivided into four genetic groups: (1) xenogenic detrital (mainly rounded); (2) magmatogene (protolith crystal in the center and growth zone at the edge); (3) hydrothermally altered (with new-formed regeneration edges in growth zones); (4) metamict-altered (unconsolidated center of the crystal and sectoring in growth zones). Based on SHRIMP U-Pb dating for the principal heterogeneous elements in every group, the following stages of ore formation have been identified for the Pebble deposit: (a) crystallization of quartz diorite-porphyry bosses (95–92 Ma, the concordant age is 94.7 ± 1.5 Ma); (b) late magmatic metasomatic alterations with copper-molybdenum mineralization (92–85 Ma, the concordant age is 90.15 ± 0.78 Ma); (c) postmagmatic argillization with epithermal gold-sulfide mineralization (82–80 Ma, the concordant age is 82.9 ± 2.7 Ma).
ISSN:1028-334X
1531-8354
DOI:10.1134/S1028334X12020146