PLATINUM-GROUP MINERALS IN DOLERITES FROM ALEXANDRA LAND ISLAND (Franz Josef Land Archipelago)
E.V. Sklyarov1, Yu.V. Karyakin2, N.S. Karmanov3, N.D. Tolstykh3
1Far Eastern Federal State University, ul. Sukhanova 8, Vladivostok, 690950, Russia
2Geological Institute, Russian Academy of Sciences, Pyzhevsky per. 7, Moscow, 119017, Russia
3V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
Keywords: Мантийный плюм, крупная изверженная провинция, базальтовый магматизм, золото-медно-палладиевая минерализация, Земля Франца-Иосифа, Mantle plume, large igneous province, basaltic magmatism, Cu-PGE-Au mineralization, Franz Josef Land Archipelago
Abstract
Lavas in Alexandra Land Island of the Franz Josef Land Archipelago bear Au-Cu-Pd-type mineralization. The found mineral species belong to the Cu-Au-Pd and Pd-Cu-(Te + Sb + S + As) systems being, respectively, (i) cuproauride (Au(Cu, Pd)) and auricupride (Au(Cu,Pd)3) and (ii) phases similar to skaergaardite (PdCu), nielsenite (PdCu3), and numerous S-Te-Sb-Pd-Cu phases of various compositions. The morphology of PGM existing as tiny grains and films along the boundaries of plagioclase and clinopyroxene and in cracks, their crystallization at low temperatures predicted by experimental data, and the presence of native copper with sulfur impurity are signatures of postmagmatic origin. The Alexandra Land tholeiitic basalts and dolerites were, most likely, produced by the hotspot which may be the source of PGE-bearing intrusions in eastern Greenland that contain PGM similar to those discussed in the paper.
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