Abstract
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).
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Original Russian Text © A.A. Kremenetskii, V.S. Popov, N.A. Gromalova, 2012, published in Doklady Akademii Nauk, 2012, Vol. 442, No. 5, pp. 653–658.
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Kremenetskii, A.A., Popov, V.S. & Gromalova, N.A. The formation age of ores from the Pebble Cu-Au-Mo giant deposit (Alaska, United States). Dokl. Earth Sc. 442, 196–201 (2012). https://doi.org/10.1134/S1028334X12020146
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DOI: https://doi.org/10.1134/S1028334X12020146