Pyasino–Vologochan intrusion: Geological structure and platinum–copper–nickel ores (Norilsk Region)

• Published in: Geology of ore deposits 2015-09, Vol.57 (5), p.381-401
• Main Authors: Sluzhenikin, S. F., Krivolutskaya, N. A.
• Format: Article
• Language: English
• Subjects: Earth and Environmental Science; Earth Sciences; Mineral Resources
• ISSN: 1075-7015; 1555-6476
• DOI: 10.1134/S1075701515050050

Rocks enriched in olivine, such as olivine and picritic gabbro–dolerite and troctolite are abundant in the Pyasino–Vologochan intrusion. In contrast to Norilsk type ore-bearing massifs, ultramafic rocks of the intrusion are dominated by troctolite. Picritic gabbro–dolerite and troctolite are located between olivine and olivine-bearing gabbro–dolerite. These rocks are related by gradual transitions. The rocks are enriched in olivine, but depleted in magnesium relative to the Norilsk type ore-bearing massifs. The intrusion is also distinguished by low chromium content in the rocks. Most disseminated Pt–Cu–Ni ores are confined to troctolite and picritic gabbro–dolerite, and to a lesser extent, to contact and olivine gabbro–dolerite. The ore is mainly observed as low-sulfur assemblages of sulfides with troilite, Fe-rich hexagonal pyrrhotite, Fe-rich chalcopyrite, talnakhite, Fe-rich pentlandite, and cubanite. The total content of platinum group elements (PGE) in the ore (ppm) is as follows: from 0.45–3.47 to 7.8; gold, from 0.05–0.24 to 0.49; and silver, from 0.53–4.50 to 8.30. Disseminated ores of the Pyasino–Vologochan intrusion contain the following Pt and Pd minerals: sobolevskite, Te-sobolevskite, Te-insizwaite, maslovite, paolovite, zvyagintsevite, atokite, niggliite, mertieite II, guanglinite, and Pd 2 (As,Sb), Pd 2 (Sn,As), Pd 3 Sb, (Pd,Ni) 2 As minerals. The similarities and differences between the Pyasino–Vologochan intrusion and Norilsk type ore-bearing massifs are discussed in this paper.