Portal de Periódicos da CAPES

The Waterberg Platinum Group Element Deposit: Atypical Mineralization in Mafic-Ultramafic Rocks of the Bushveld Complex, South Africa

2017; Volume: 112; Issue: 6 Linguagem: Inglês

10.5382/econgeo.2017.4513

1554-0774

Judith A. Kinnaird, Marina A. Yudovskaya, Matthew McCreesh, F.M. Huthmann, Thys J. Botha,

Geochemistry and Elemental Analysis

Research Article| September 01, 2017 The Waterberg Platinum Group Element Deposit: Atypical Mineralization in Mafic-Ultramafic Rocks of the Bushveld Complex, South Africa Judith A Kinnaird; Judith A Kinnaird † 1Economic Geology Research Institute, University of the Witwatersrand, 2050 Wits, South Africa2Centre of Excellence for Integrated Mineral and Energy Resource Analysis, The National Research Foundation/Department of Science and Technology Centre of Excellence, University of the Witwatersrand, 2050 Wits, South Africa †Corresponding author: e-mail, Judith.Kinnaird@wits.ac.za Search for other works by this author on: GSW Google Scholar Marina Yudovskaya; Marina Yudovskaya 1Economic Geology Research Institute, University of the Witwatersrand, 2050 Wits, South Africa2Centre of Excellence for Integrated Mineral and Energy Resource Analysis, The National Research Foundation/Department of Science and Technology Centre of Excellence, University of the Witwatersrand, 2050 Wits, South Africa3Institute of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry, Russian Academy of Science, 35, Staromonetny, Moscow 119017, Russia Search for other works by this author on: GSW Google Scholar Matthew McCreesh; Matthew McCreesh 1Economic Geology Research Institute, University of the Witwatersrand, 2050 Wits, South Africa2Centre of Excellence for Integrated Mineral and Energy Resource Analysis, The National Research Foundation/Department of Science and Technology Centre of Excellence, University of the Witwatersrand, 2050 Wits, South Africa Search for other works by this author on: GSW Google Scholar Florian Huthmann; Florian Huthmann 1Economic Geology Research Institute, University of the Witwatersrand, 2050 Wits, South Africa3Institute of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry, Russian Academy of Science, 35, Staromonetny, Moscow 119017, Russia Search for other works by this author on: GSW Google Scholar Thys J. Botha Thys J. Botha 4PTM, Platinum House, 24, Sturdee Avenue, Rosebank, Johannesburg Search for other works by this author on: GSW Google Scholar Author and Article Information Judith A Kinnaird † 1Economic Geology Research Institute, University of the Witwatersrand, 2050 Wits, South Africa2Centre of Excellence for Integrated Mineral and Energy Resource Analysis, The National Research Foundation/Department of Science and Technology Centre of Excellence, University of the Witwatersrand, 2050 Wits, South Africa Marina Yudovskaya 1Economic Geology Research Institute, University of the Witwatersrand, 2050 Wits, South Africa2Centre of Excellence for Integrated Mineral and Energy Resource Analysis, The National Research Foundation/Department of Science and Technology Centre of Excellence, University of the Witwatersrand, 2050 Wits, South Africa3Institute of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry, Russian Academy of Science, 35, Staromonetny, Moscow 119017, Russia Matthew McCreesh 1Economic Geology Research Institute, University of the Witwatersrand, 2050 Wits, South Africa2Centre of Excellence for Integrated Mineral and Energy Resource Analysis, The National Research Foundation/Department of Science and Technology Centre of Excellence, University of the Witwatersrand, 2050 Wits, South Africa Florian Huthmann 1Economic Geology Research Institute, University of the Witwatersrand, 2050 Wits, South Africa3Institute of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry, Russian Academy of Science, 35, Staromonetny, Moscow 119017, Russia Thys J. Botha 4PTM, Platinum House, 24, Sturdee Avenue, Rosebank, Johannesburg †Corresponding author: e-mail, Judith.Kinnaird@wits.ac.za Publisher: Society of Economic Geologists Accepted: 15 Mar 2017 First Online: 25 Aug 2017 Online Issn: 1554-0774 Print Issn: 0361-0128 © 2017 Society of Economic Geologists.Society of Economic Geologists Economic Geology (2017) 112 (6): 1367–1394. https://doi.org/10.5382/econgeo.2017.4513 Article history Accepted: 15 Mar 2017 First Online: 25 Aug 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Judith A Kinnaird, Marina Yudovskaya, Matthew McCreesh, Florian Huthmann, Thys J. Botha; The Waterberg Platinum Group Element Deposit: Atypical Mineralization in Mafic-Ultramafic Rocks of the Bushveld Complex, South Africa. Economic Geology 2017;; 112 (6): 1367–1394. doi: https://doi.org/10.5382/econgeo.2017.4513 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyEconomic Geology Search Advanced Search Abstract The exposed northern limb of the Bushveld Complex forms the eastern part of a much larger basin, ~160 X –125 km in size based on geophysical data. Within this basin, the recently discovered ultramafic-mafic succession that extends 24 km northeast from the Hout River shear zone has been shown to have a Bushveld intrusion age of 2.06 Ga. The succession is typically 1 km thick, dips west at 34° to 38°, and comprises a basal Ultramafic sequence, a troctolite-gabbronorite-anorthosite sequence, and an Upper zone. Overlying Waterberg red beds were deposited between ~2.05 and ~1.93 Ma. The basal Ultramafic sequence comprises a lower orthopyroxenite <60 m thick overlying Archean granite gneisses with an intervening agmatite, which is interpreted to be remobilized footwall gneiss interfingered with pyroxenite. The upper portion of the Ultramafic sequence is composed of serpentinized harzburgite. The troctolite-gabbronorite-anorthosite sequence is <850 m thick and is dominated by gabbronorites with minor anorthosites at the top and thick troctolite layers <50 m thick, which are locally pegmatoidal, toward the base. The boundary with the Upper zone is defined by increased magnetic susceptibility due to increased cumulus magnetite. The Upper zone of ferrogabbro and magnetite gabbronorite varies between 0 and 500 m in thickness. Disseminated magnetite is ubiquitous but magnetitite layers that are characteristic of the Upper zone elsewhere in the Bushveld Complex are lacking, except in one core from the extreme south of the project.There are two PGE-Cu-Ni-Au mineralized intervals, a lower F zone and an upper T zone that vary from 3 to 60 m in thickness. The T zone is restricted to the southern portion of the project, whereas the F zone extends 17 km along strike. In both there is a correlation between visible chalcopyrite and pentlandite abundance and grade of PGE. The F zone of the Ultramafic sequence hosts disseminated sulfides with accessory chromite. Platinum group minerals (PGM), based on more than 1,000 grains recovered, are dominated by sperrylite with lesser Pt-Pd bismuthotellurides, Au-Ag alloys, Pd arsenides, and Pt-Rh sulfoarsenide with a grade of 50 m thick. An upper T1 and lower T2 are separated by a barren middling that is sometimes absent. Grade in both T1 and T2 is indicated as 3.88 g/t Pt + Pd + Rh + Au, although locally with up to 14 g/t. PGM are less varied than in the F zone and are dominated by Pt-Pd bismuthotellurides. Both T1 and T2 zones have a consistent and unusually gold-enriched metal ratio of ~49% Pd, ~29% Pt, 1% Rh, and 21% Au with 0.08% Ni and 0.16% Cu. Neither the T nor F mineralized zones has direct correlatives in other limbs of the Bushveld Complex.Although there are comparisons with the Bushveld succession elsewhere, significant differences in thickness and type of lithologies, geochemistry, and mineralization of this arcuate intrusion of the Waterberg segment, compared to the eastern, western, and northern limbs of the Bushveld Complex, suggest that the Waterberg ultramafic-mafic body may represent a structurally controlled separate compartment north of the Hout River shear zone. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.