Permian-Triassic granitoid magmatism and metallogeny of the Hangayn (central Mongolia)
D. Orolmaa a , G. Erdenesaihan a , A.S. Borisenko b, c , G.S. Fedoseev b, c , V.V. Babich b , S.M. Zhmodik b
a Institute of Geology and Mineral Resources, Mongolian Academy of Sciences, 63 Enhtayvan ave., Ulaanbaatar, 210351, Mongolia
b Institute of Geology and Mineralogy, Siberian Branch of the RAS, 3 prosp. Akad. Koptyuga, Novosibirsk, 630090, Russia
c Novosibirsk State University, 2 ul. Pirogova, Novosibirsk, 630090,Russia
Keywords: Geochronology; metallogeny; within-plate magmatism; granitoids; geochemistry; Central Mongolia
Pages: 534-544
Abstract
We report new isotope dates and metallogenic and chemical characteristics of granitoids from the Hangayn area (central Mongolia) with implications for the time and tectonic settings of their formation. Proximal U-Pb and Ar-Ar ages of 241.3 ± 1.5 Ma and 238.2 ± 2.5 Ma have been obtained for the Triassic Guchin Us and Hurmen Gol intrusions, respectively, and an Early Permian age (288.7 ± 2.3 Ma, Ar-Ar) for the Bayanulaan granite and for granite porphyry from the Saran Uul Cu-Mo-(Au) deposit. Granitoids of the Egiyn Davaa, Hangayn, and Shar Us Gol complexes in the southwestern Hangayn area are of two geochemical types. Some intrusions that were formerly attributed to these complexes have been reinterpreted as resulting from multiple plutonic pulses of different ages. According to our new data and published evidence, most of granitoids in the area may have been produced by Early-Middle Triassic (255-230 Ma) rather than Permian and Late Triassic-Early Jurassic events. The Hangayn granitoids are of low mineral potential. Gold mineralization in the area is confined within the Hangayn gold belt and appears to be independent of the intrusions.
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