The composition of magmatic Ni-Cu-(PGE) sulfide deposits in the Tati and Selebi-Phikwe belts of eastern Botswana

Maier, Wolfgang D.; Barnes, Sarah‐Jane; Chinyepi, G.; Barton, J. M.; Eglington, B. M.; Setshedi, I.

doi:10.1007/s00126-007-0169-8

Cited by 5 publications

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“…Sulfide mineralization in the Duke Island Complex represents a class of deposit formed in a convergent plate setting that has historically been considered rare. However, current research is beginning to show that magmatic sulfide mineralization in this tectonic setting may be more common than initially thought [e.g., Maier et al , 2008]. Salient points reached from our study of the Duke Island Complex include:…”

Section: Discussionmentioning

confidence: 97%

“…The general tectonic setting is that of a convergent zone [ Tornos et al , 2001; Piña et al , 2006]. Other convergent zone‐related intrusions with sulfide mineralization include the Riwaka intrusion of New Zealand [ Smits et al , 2004], the Rana Intrusion in Norway [ Boyd and Mathiesen , 1979; Barnes , 1987], the Phoenix and Selkirk deposits in Botswana [ Maier et al , 2008], the St. Stephen and Moxie intrusions in the Appalachians [ Thompson , 1984; Paktunc , 1989] and the Vammala intrusion in Finland [ Peltonen , 2003]. However, the rarity of world‐class magmatic Cu‐Ni‐PGE sulfide deposits in subduction zones has led to the general tenet that compressional tectonic regimes are unfavorable for the genesis of such deposits.…”

Section: Introductionmentioning

confidence: 99%

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Geochemical constraints on the origin of sulfide mineralization in the Duke Island Complex, southeastern Alaska

Thakurta

Ripley

2008

Geochem Geophys Geosyst

130

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[1] Magmatic Cu-Ni-PGE sulfide mineralization associated with mafic to ultramafic igneous rocks is rare in convergent plate settings. However, recent exploration in the Duke Island Complex of southeastern Alaska has detected horizons of sulfide mineralization primarily in the olivine clinopyroxenite unit. The composition of the sulfides, recalculated to 100% sulfide, averages 0.48% Ni and 1.4% Cu. The Duke Island Complex was generated by the emplacement of multiple pulses of variably fractionated magma ranging in composition from picrite to ankaramite that originated in deeper staging chambers. The presence of sulfides in the complex indicates that fO 2 conditions were more reduced than those commonly ascribed to arc-related magmas. The mass of sulfide mineralization together with the sulfur isotopic values indicates that external sulfur was added to the parent magmas at staging chambers. Os isotopic data from sulfides and C isotopic compositions of graphite in the olivine clinopyroxenites also indicate that the parental magmas were contaminated by crustal material. However, oxygen isotopic values of clinopyroxene together with the REE data suggest that bulk assimilation of country rocks has not occurred and the contamination was selective, involving C-and S-bearing fluids or graphitic sulfides. The observed enrichment in Cu and S isotopic values of the sulfides is best explained by assimilation of sulfides from metal-bearing rock types such as black shales or volcanogenic massive sulfide deposits that occur in terranes above the mantle wedge.

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Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Geochemical constraints on the origin of sulfide mineralization in the Duke Island Complex, southeastern Alaska

Thakurta

Ripley

2008

Geochem Geophys Geosyst

130

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“…The TGB, which hosts numerous mineral deposits, including magmatic Ni-Cu (PGE) ore deposits and Au-Ag deposits (Aldiss, 1991;Maier et al, 2008), forms part of the Francistown Granite-Greenstone Complex located in the southern extremity of the Zimbabwe Craton (60,000 km 2 ) in northeastern Botswana and separated from the Kaapvaal Craton by the Limpopo Mobile Belt (Carney et al, 1994;McCourt et al, 2004) (Figures 1a,b and 2a). The belt was deposited at $2700 Ma (Jelsma & Dirks, 2002;Wilson et al, 1978), underwent low to medium grade metamorphism from 2630 ± 70 to 2570 ± 70 Ma, and was intruded by granitoids of tonalitic composition and late WNW-trending dolerite dykes of the Karoo age (180-310 Ma) (Carney et al, 1994;Glanvill et al, 2011;Key, 1976).…”

Section: Regional Geologymentioning

confidence: 99%

“…The Lady Mary Formation forms the basement of the TGB and consists of altered komatiite and komatiitic basalt with local development of pillow structures within basaltic rocks (Carney et al, 1994;Maier et al, 2008). Metasedimentary rocks, including quartz schists, phyllites, limestones, and iron formations, are also part of this formation.…”

Section: Regional Geologymentioning

confidence: 99%

Mineralogical and sulfur isotopic characteristics of Archean greenstone belt‐hosted gold mineralization at the Tau deposit of the Mupane gold mine, Botswana

et al. 2023

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The Mupane gold deposit, which is one of the numerous gold occurrences in the Tati Greenstone Belt in the northeastern part of Botswana, consists of four orebodies, namely Tau, Tawana, Kwena, and Tholo deposits. The present research, which focuses on the genesis of the Tau deposit, was based on ore petrography, mineral chemistry of sulfides, and sulfur isotope data. Mineralogical characteristics of the host rocks indicate that banded iron formation at the Tau deposit includes iron oxides (magnetite), carbonates (siderite and ankerite), silicates (chlorite and amphibole), and sulfides (arsenopyrite and pyrrhotite). The deposit features arsenopyrite‐rich zones associated with biotite‐chlorite veins, which are indicative of the precipitation of arsenopyrite concomitant with potassic alteration. The replacement of magnetite by pyrrhotite in some samples suggests that sulfidation was likely the dominant gold precipitation mechanism because it is considered to have destabilized gold‐thiocomplexes in the ore‐forming fluids. Based on textural relationships and chemical composition, arsenopyrite is interpreted to reflect two generations. Arsenopyrite 1 is possibly early in origin, sieve textured with abundant inclusions of pyrrhotite. Arsenopyrite 1 was then overgrown by late arsenopyrite 2 with no porous textures and rare inclusions of pyrrhotite. Gold mineralization was initiated by focused fluid flow and sulfidation of the oxide facies banded iron formation, leading to an epigenetic gold mineralization. The mineralogical assemblages, textures, and mineral chemistry data at the Tau gold deposit revealed two‐stage gold mineralizations commencing with the deposition of invisible gold in arsenopyrite 1 followed by the later formation of native gold during hydrothermal alteration and post‐depositional recrystallization of arsenopyrite 1. Laser ablation inductively coupled plasma mass spectrometric analysis of arsenopyrite from the Tau deposit revealed that the hydrothermal event responsible for the formation of late native gold also affected the distribution of other trace elements within the grains as evidenced by varying trace elements contents in arsenopyrite 1 and arsenopyrite 2. The range of δ34S of gold‐bearing assemblages from the Tau deposit is restricted from +1.6 to +3.9‰, which is typical of Archean orogenic gold deposits and indicates that overall reduced hydrothermal conditions prevailed during the gold mineralization process at the Tau deposit. The results from this study suggest that gold mineralization involved multi‐processes such as sulfidation, metamorphism, deformation, hydrothermal alteration, and gold remobilization.

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“…In these compressive environments, the mafic-ultramafic intrusions have been correlated to a variety of sources and pathways for magma generation and emplacement. A few intrusions located in orogenic environments are interpreted to be pre-orogenic, but most of them are interpreted to be syn-collisional, commonly related to cumulates of magmatic arc roots or even backarc basins, and some can be related to post-orogenic settings, commonly linked to mantle plumes and/or LIPs (e.g., Barnes et al, 2019;Le Vaillant et al, 2020a;Maier et al, 2008;Piña, 2019;Sappin et al, 2012) The Americano do Brasil Complex is part of a group of mafic-ultramafic intrusions occurring in the southern segment of the Goiás Magmatic Arc, in the Neoproterozoic Brasilia Belt. The intrusions are broadly associated with the Brazilian Orogeny and have been interpreted as syntectonic intrusions associated with the second magmatic event in the Arenópolis Arc, but the specifics of the origin and emplacement of these mafic bodies are poorly constrained (Nilson and Santos, 1982;Laux et al, 2004;Augustin and Della Giustina, 2019).…”

Section: Objectivesmentioning

confidence: 99%

Petrogenesis of Mafic-Ultramafic Intrusions in the Southern Goiás Magmatic Arc, Central Brazil

Augustin¹

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The Americano do Brasil and Mangabal Complexes belong to a cluster of Neoproterozoic mafic-ultramafic intrusions in the southern Goiás Magmatic Arc in Brazil that lies within the Brasília Belt, a complex, long-lived Neoproterozoic Orogen that formed during the amalgamation of the São Francisco/Congo, Amazonian, and Paranapanema Cratons in western Gondwana. Although deformed and partially recrystallized by a regional metamorphic overprint, the rocks of both complexes still preserve igneous textures. The rocks in both complexes show cumulate textures that range from adcumulate to orthocumulate. Petrography, geochemistry, geochronology, and petrological modeling were carried out to constrain the petrogenesis of the complexes.Modeling indicates that the parental magma for the Americano do Brasil Complex had an OIB-like Fe-rich picrite composition, while the parental magma of the Mangabal Complex could have been a tholeiitic basalt. Considering the temporal and spatial correlations, decompression melting of upwelling asthenosphere triggered by rollback subduction and/or influence of a mantle plume are plausible mechanisms to explain the petrogenesis of these mafic-ultramafic intrusions in the vicinities of the eastern Arenópolis arc and westernmost Anápolis-Itauçu belt. The complexes have experienced a protracted metamorphic evolution with peaks indicating amphibolite facies. The rock from both complexes shows late-stage alteration associated with metasomatism by CO2-Ca-S-rich fluids.

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The composition of magmatic Ni-Cu-(PGE) sulfide deposits in the Tati and Selebi-Phikwe belts of eastern Botswana

Abstract: Unfortunately, the tick marks of the picrite-crust mixing lines in Fig. 5 have been plotted erroneously. As a result, the correct value of crustal component is < ca. 5% at Tati (not <10-20% as stated in the text) and > ca 5% at PhikweDikoloti (as opposed to >10-20%).

Cited by 5 publications

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Geochemical constraints on the origin of sulfide mineralization in the Duke Island Complex, southeastern Alaska

Geochemical constraints on the origin of sulfide mineralization in the Duke Island Complex, southeastern Alaska

Mineralogical and sulfur isotopic characteristics of Archean greenstone belt‐hosted gold mineralization at the Tau deposit of the Mupane gold mine, Botswana

Petrogenesis of Mafic-Ultramafic Intrusions in the Southern Goiás Magmatic Arc, Central Brazil

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