Platinum-group minerals in dolerites from Alexandra Land Island (Franz Josef Land Archipelago)

摘要

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. (C) 2016, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.