Geochemistry and mineralogy of banded iron-formation-hosted gold mineralization in the Gwanda greenstone belt, Zimbabwe

Saager, R.; Oberthuer, Thomas; Tomschi, H P

doi:10.2113/gsecongeo.82.8.2017

Cited by 21 publications

(11 citation statements)

References 12 publications

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“…An additional gain of some ore components could have been provided by the solutions that circulated along latitudinal tectonic zones under conditions of deficiency in sulfur. The mineralization at the southern Kostomuksha prospect may be referred to as the gold-sulfide (arsenopyrite) type in shear zones localized in the BIF (Zimbabwe type, after Saager et al, 1987), i.e., juxtaposed with oxide ores.…”

Section: Discussionmentioning

confidence: 99%

“…Tables 1 and 1A):(1)(2)(3)(4) loellingite,(5)(6)(7)(8)(9)(10)(11)(12)(13) arsenopyrite,(14) pyrite,(15)(16)(17)(18) pyrrhotite, (19, 20) chalcopyrite, (21) sphalerite, (22-27) galena. Analyses 1, 2, 11-13 correspond to sample GP-1/11; analyses 3, 9, 15, 26, 27, to sample 710; analyses 4, 7, 8, 14, 17, 19, to sample GP-3/1; analyses 5, 6, to sample 1/12; analyses 10, 16, to sample K-6/21; analyses 18, 20-24, to sample GP-1/33; analysis 25, to sample GP-1/15.…”

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confidence: 99%

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Mineralogy of the Precambrian southern Kostomuksha gold prospect in Karelia

Kuleshevich

Gor’kovets

2008

Geol. Ore Deposits

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The southern Kostomuksha gold-sulfide prospect with a grade of 0.2-30 g/t Au belongs to the gold-pyrrhotite-arsenopyrite mineral type and is localized in the metasomatically altered shear zone at the southern flank of the Kostomuksha iron deposit. The Au-bearing pyrite ore is commonly characterized by a low grade (0.02-1.0 g/t Au). The grade of Au-bearing mineralization composed of arsenopyrite, loellingite, and electrum (4.28-15.31 wt % Ag and up to 0.99-2.16 wt % Hg) is higher; pyrrhotite, chalcopyrite, galena, maldonite, aurostibite, and native bismuth are additional components of this mineral assemblage. The ore mineralization is hosted in the near-latitudinal shear zone close to the contact between the folded and metamorphosed banded iron formation (BIF) and hälleflinta. The early stage of collision-related HP-HT metamorphism resulted in the formation of a garnet-amphibole-biotite assemblage ( T = 680-750 ° C) and microcline. After an abrupt drop m pressure, metasomatic alteration and ore mineralization took place. The ore-forming process started at 510-440 ° C with deposition of arsenopyrite. Galena and electrum were formed at a lower temperature. The temperature continued to decline down to the stage of ore oxidation and deposition of colloform marcasite. Ore minerals precipitated from acid chloride aqueous solutions admixed with methane at the initial stage and from diluted aqueous solutions at the final stage. The character of wall-rock alteration and the gain of K, Rb, and B show that the ore-forming process postdated the emplacement of potassium granite. The occurrence of Cu, Zn, Pb, As, and Ni and other heterogeneous elements indicates a complex metamorphic-metasomatic source and an additional supply of Au, As, Bi, Sb, and Te under conditions of sulfur deficiency. The gold mineralization at the southern Kostomuksha prospect is classified as gold-sulfide (arsenopyrite) ore type related to shear zones in the BIF.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Mineralogy of the Precambrian southern Kostomuksha gold prospect in Karelia

Kuleshevich

Gor’kovets

2008

Geol. Ore Deposits

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“…The multistage model postulates that gold is a primary component of the iron formation and is remobilized and concentrated during later events Sawkins and Rye, 1974;Fripp, 1976a;Saager et al, 1987;.…”

Section: Chapter I Palladium-bearing Gold Deposit Hosted By Proterozomentioning

confidence: 99%

“…The iron mine open pits correspond to the northern and western sectors of the iron-formation unit which is complete outcrop 153 Proposed evolutionary model for the Minas Supergroup (adapted from . Stage l= opening of the Minas basin (2.4-2.6 Ga, ; Stage II A= basin closure following by folding, metamorphsim and thrusting of the Minas sequence (1.9-2.2 Ga, ; and B= Average of REE elements of Lake Superior-type oxide fades iron-formation 54 Table 1.7: Gold grades of samples from the Cauê gold orebodies analyzed by fire-assay techniques 56 and an average of 4 analyses obtained by energy-dispersive system analyses (*, with 0.15% Mn) are given for comparison 109 (Lindgren, 1933;Sawkins and Rye, 1974), the Morro Velho Mine in Brazil (Orville, 1902;Lindgren, 1933;Gair, 1962and Ladeira, 1985 Vulbachikwe in Zimbabwe (Fripp, 1976a,b;Saager et al, 1987;, as well as deposits in Western Australia , Canada (Fryer et al, 1979;Kerrich and Fryer, 1979;Macdonald, 1983;Padgham, 1984;Anglin and Franklin, 1985;Kerswill, 1986;Wyman et al, 1986;Lhotka andNesbitt, 1989, Gibbins et al, 1991), India (Hamilton and Hodgson, 1986), and several mines in Brazil Vial, 1988aVial, e 1988bVieira, 1988;Vieira and Oliveira, 1988;Leao de Sa and Borges, 1991;Vieira, 1991).…”

Section: Introductionmentioning

confidence: 99%

Les gites d or palladiferes des mines de Caue et de Conceicao dans les formations de fer du type lac Superieur du district d Itabira Craton Sao Francisco Bresil structure mineralogie geochronologie et metallogenie = (Palladium-bearing gold deposits of the caue and conceicao mines hosted by lake superior-type iron-formations of the Itabira district Sao Francisco craton Brazil structure mineralogy geochronology and metallogeny)

Olivo¹

1994

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“…The widespread occurrence of primary gold concentrations in Algoma-type iron formation is well established (Crocket et al 1981, up to 0.363 ppm Au;Saager et al 1982, 0.0005-0.667 ppm Au;Gross 1988,0.001-0.130 ppm Au). However, minable gold deposits have been found only in metamorphosed and deformed iron formation that contains crosscutting quartz veins or sulfide-rich zones in Fe-silicate or oxide layers (Phillips et al 1984;Saager et al 1987;Lhotka and Nesbitt 1989). Phillips et al (1984) suggested that crosscutting fractures (often mineralized quartz veins) with symmetrical alteration and sulfidation fronts are evidence of an epigenetic introduction of gold into BIF.…”

Section: Origin Of Gold In Iron Formationmentioning

confidence: 99%

Auriferous chert, banded iron formation, and related volcanogenic hydrothermal alteration, Atik Lake, Manitoba

Bernier¹,

MacLean²

1989

Can. J. Earth Sci.

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Small-scale alteration pipes and stratiform alteration in Archean glomeroporphyritic tholeiitic basalts at Atik Lake, Manitoba, stratigraphically underlie silicate-oxide banded iron formation @IF) and auriferous sulfide-bearing chert. The auriferous chert is locally interbedded with graphitic argillite, indicating euxinic conditions during deposition. Cordierite-gedrite rocks formed by recrystallization of alteration assemblages during the lower amphibolite-facies metamorphism (T = 550°C, P = 2.5 kbar). A1,0,, TiO,, Zr, and Nb, which were relatively immobile during alteration, have been used to monitor igneous differentiation and alteration. Volcanogenic hydrothermal alteration resulted in depletion of Ca, Si, Mg, Na, and Sr in the altered basalt and the addition of K, Fe, Rb, and Ba. This was accompanied by mass and volume losses of up to 25%. The mineralizing fluid was reducing and somewhat acidic. Rare-earth-element (REE) profiles of BIF and graphitic argillite, normalized to Archean shale, are less steep ((LalLu), = 0.51 and 0.49 respectively), than those of both mineralized chert ((LalLu), = 0.04) and recent sea-floor, siliceous, gold-enriched massive sulfides ((LalLu), = 0.11). REE profiles and Bostriim's plot suggest that the auriferous, sulfide-bearing chert formed by mixing of hydrothermal and detrital components. The overall chemical changes in the Atik Lake alteration system are comparable to those in Noranda-type massive-sulfide deposits. The trace-metal association in the auriferous chert is similar to that at some modem sea-floor hydrothermal sites. Une altkration i petite kchelle de cheminkes et une altkration stratiforme dans les basaltes tholkiitiques, glomkroporphyriques, d'bge archken, au lac Atik, Manitoba, apparaissent en position stratigraphiquement sous-jacentes ?i une formation fenugineuse rubanke de silicates et oxydes et ?i une couche de chert minkraliske en sulfures et or. Ce chert aurifere est localement interlitk avec une argilite graphitique, donc un milieu euxknique de dtp6t. Les roches ?i cordikrite-gkdrite ont kt6 formkes par la recristallisation des assemblages d'altkration durant une pkriode d'activitk mktamorphique dans le fac5s des amphibolites de faible degk (T = 550°C, P = 2,5 kbar). Les composantes A1,0,, TiO,, Zr et Nb, relativement irnmobiles durant l'altkration, ont semi de point de repkre dans l'ktude de la diffkrenciation magmatique et de l'altkration. L'altkration volcanogknique hydrothermale a ckk un appauvrissement en Ca, Si, Mg, Na et Sr dans le basalte altkrk et un enrichissement en K, Fe, Rb et Ba. Le tout fut accompagnk par des nkluctions de rnasse et de volume pouvant atteindre jusqu'i 25 % . Le fluide minkralisateur ktait rtducteur et quelque peu acide. Les diagrammes des terres rares de la formation fermgineuse rubanke et de l'argilite graphitique, normalisks au shale archken, sont moins abrupts ((LatLu), = 0,51 et 0,49 respectivement) que ceux du chert mintralisk ((LatLu), = 0,04) et Cgalement que ceux des sulfures massifs siliceux enrichis en or sur fond oc...

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Geochemistry and mineralogy of banded iron-formation-hosted gold mineralization in the Gwanda greenstone belt, Zimbabwe

Cited by 21 publications

References 12 publications

Mineralogy of the Precambrian southern Kostomuksha gold prospect in Karelia

Mineralogy of the Precambrian southern Kostomuksha gold prospect in Karelia

Auriferous chert, banded iron formation, and related volcanogenic hydrothermal alteration, Atik Lake, Manitoba

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