Platinum mineralization of the Svetly Bor and Nizhny Tagil intrusions,Ural Platinum Belt |
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| Institution: | 1. Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Ak. Koptyga, 3, 630090 Novosibirsk, Russia;2. Institute of Comprehensive Exploitation of Mineral Resources, Russian Academy of Sciences, Kryukovskiy tupic, 4, 111020 Moscow, Russia;3. Prospector Ltd, Vostochnaya Str., 56 (818), 620075 Ekaterinburg, Russia;1. State Key Laboratory of Geological Processes and Mineral Resources, Faculty of the Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China;2. Department of Geology, University of Regina, S4S 0A2 Regina, Canada;3. State Agency of Geology and Mineral Resources, Bishkek, Kyrgyzstan;1. CONICET, Universidad Nacional de La Plata, Instituto de Recursos Minerales (INREMI), Calle 64 y 120, B1900FWA, La Plata, Argentina;2. CIC-BA, Universidad Nacional de La Plata, Instituto de Recursos Minerales (INREMI), Calle 64 y 120, B1900FWA, La Plata, Argentina;1. School of the Earth Science and Mineral Resources, China University of Geosciences, Beijing 100083, China;2. MLR Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China;3. Centre for Exploration Targeting, University of Western Australia, 35 Stirling Highway, Crawley, WA 6008, Australia;4. Technology and International Cooperation Department, Ministry of Land and Resources, Beijing 100812, China;5. CNNC Beijing Research Institute of Uranium Geology, Beijing 100029, China;1. Development Research Centre, China Geological Survey, Beijing 100037, PR China;2. School of Earth Science and Mineral Resources, China University of Geosciences, Beijing 100083, PR China;1. Universidade Federal de Minas Gerais, CPMTC-Instituto de Geociências, Av. Presidente Antônio Carlos, 6627, Pampulha, Belo Horizonte – MG, Brazil;2. Aurizona Mineração: Avenida dos Holandeses, Ponta do Farol, São Luís – MA, Brazil;3. Centro de Desenvolvimento da Tecnologia Nuclear - CDTN/SETEM, R.Prof. Mario Wernek s/n Campus da Pampulha, Belo Horizonte, MG - Brasil;4. The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia |
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| Abstract: | This paper presents the results of a detailed mineralogical and micro analytical study of two Ural-Alaskan type intrusions in the Ural Platinum Belt: (1) the dunite-hosted mineralization of the Svetly Bor intrusion, and (2) the chromitite mineralization of the Nizhny Tagil intrusion. Two generations of platinum minerals are typical of both intrusions: magmatic Pt–Fe(Ni) alloys, and post-magmatic Pt(Fe,Ni,Cu) alloys. A trend from ferroan platinum to isoferroplatinum (Pt,Fe → Pt3Fe) is shown for magmatic alloys of the Svetly Bor intrusion. Magmatic alloys of the Nizhny Tagil intrusion are represented by ferroan platinum (with Ni) only, varying in Fe. The magmatic Pt–Fe alloys of both intrusions were depleted in Fe during the evolution of ore-forming systems and crystallized during the entire magmatic process, generally as fine cubic crystals and anhedral grains hosted by dunite at the magmatic stage during and after the crystallization of dunite (platinum–dunite type of the Svetly Bor intrusion). The evolution of mineral paragenesis was accompanied by a temperature drop, as well as increases in fO2 and fS2.Most of the platinum was concentrated in the residual melts together with chromium, and crystallized in the final stage of the magmatic process (platinum–chromite ore of the Nizhny Tagil intrusion). Post-magmatic Pt(Fe,Cu,Ni) alloys formed during the serpentinization of dunite evolved according to a general compositional trend from tetraferroplatinum and ferronickelplatinum to tulameenite and later to Pt–Cu alloy and Pt-oxide (PtFe) → Pt(Fe,Cu,Ni) → Cu3Pt → Pt–O. Platinum-rich mineralization of both intrusions was formed in the late magmatic stage from a melt rich in volatiles, regardless of their location in dunite or chromitites. Most probably, the rock structure (fracture systems) was the determining factor in the migration of PGE-rich residual melts and ore accumulation. |
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