scholarly journals Banded iron formation-hosted gold mineralization in the Geraldton area, northwestern Ontario: structural setting, mineralogical characteristics and geochronology

2015 ◽  
Author(s):  
Z Tóth ◽  
B Lafrance ◽  
B Dubé ◽  
V J McNicoll ◽  
P Mercier-Langevin ◽  
...  
Keyword(s):  
Gold Mineralization ◽  
Iron Formation ◽  
Banded Iron Formation ◽  
Structural Setting ◽  
Northwestern Ontario ◽  
Mineralogical Characteristics

scholarly journals Gold Mineralization in Banded Iron Formation in the Amalia Greenstone Belt, South Africa: A Mineralogical and Sulfur Isotope Study

2013 ◽  
Vol 63 (2) ◽  
pp. 119-140 ◽  
Author(s):  
Kofi Adomako-Ansah ◽  
Toshio Mizuta ◽  
Napoleon Q. Hammond ◽  
Daizo Ishiyama ◽  
Takeyuki Ogata ◽  
...  
Keyword(s):  
South Africa ◽  
Greenstone Belt ◽  
Sulfur Isotope ◽  
Gold Mineralization ◽  
Iron Formation ◽  
Banded Iron Formation ◽  
Isotope Study

scholarly journals A Fonte dos Metais da Mina de Ouro do Schramm, Santa Catarina: Evidências de Dados de Isótopos de Pb e Elementos Terras Raras

2005 ◽  
Vol 32 (1) ◽  
pp. 51
Author(s):  
FLÁVIO FRANÇA NUNES DA ROCHA ◽  
ARTUR CEZAR BASTOS NETO ◽  
MARCUS VINÍCIUS DORNELLES REMUS ◽  
VITOR PAULO PEREIRA
Keyword(s):  
Gold Mineralization ◽  
Isotope Composition ◽  
Shear Zones ◽  
Iron Formation ◽  
Gold Mine ◽  
Banded Iron Formations ◽  
Banded Iron Formation ◽  
Santa Catarina ◽  
Lead Isotope Composition ◽  
Ree Patterns

The source of the ore elements in the Schramm gold mine, localized in central part of Santa Catarina shield, has been constrained based on lead isotope composition of galena and sulfosalts, and the rare earth element (REE) patterns of the ore. The Pb207/ Pb206 model age obtained in galena and lillianite-gustavite series from the mineralization yields an age of 1.88 Ga. It is higher than the estimated age of the deposit (» 534 Ma). The Pb isotopic composition obtained in these minerals indicates that the age of Schramm mine source is similar to that of the galena of the Ribeirão da Prata mine (Pb-Zn-Cu-Ag). This mine is located 25 Km southwest of the Schramm gold mine witch is hosted in the tension fracture zone conjugated with the first order shear zone that contains the Ribeirão da Prata deposit. The similarities between Pb-isotope compositions of both deposits could indicate that they were contemporaneous and derived from the same regional lead source. The REE patterns of the ore samples of Schramm mine are similar to that of the pyroxenites and banded iron formations from the Archean Santa Catarina Granulitic Complex that host the Schramm gold mine. They present low REE contents with flat patterns and lack Eu anomalies. The comparison among the isotopic data from this mine with those from other places indicates that the banded iron formation and mafic-ultramafic granulitic gneisses are the source of the gold mineralization. This evidence agreed with the hypothesis that the ore fluids were derived from retrogressive metamorphism reactions of Santa Catarina Granulitic Complex in the shear zones during the final stage of Brasiliano orogenic cycle.

Structure of veins in a gold–pyrite deposit in banded iron formation, Amalia greenstone belt, South Africa

1986 ◽  
Vol 123 (6) ◽  
pp. 601-609 ◽  
Author(s):  
J. R. Vearncombe
Keyword(s):  
Greenstone Belt ◽  
Quartz Vein ◽  
Gold Mineralization ◽  
Iron Formation ◽  
Banded Iron Formation ◽  
Vein Wall ◽  
Quartz Veins ◽  
Anticlockwise Rotation ◽  
Fibre Growth ◽  
Mineralizing Fluids

AbstractFibrous quartz veins in deformed banded iron formation of the Amalia greenstone belt, southwestern Transvaal, are spatially related to gold–pyrite mineralization in both wallrock and vein inclusions. Poles to quartz vein orientations show a general parallelism with mineral elongation and fold plunges of the principal deformation in the wallrock. Quartz vein fibres show a consistent anticlockwise rotation, late components being subparallel to the elongation lineation, suggesting veining was probably synchronous with the principal deformation. Antitaxial fibrous veins, which dominate the mineralized banded iron formation, formed by the process of crack–seal which channelled mineralizing fluids along the vein walls, increasing the potential for fluid–wallrock interaction. Gold mineralization in quartz veins occurs in wall-parallel slivers of banded iron formation which have been plucked off the vein wall during antitaxial fibre growth. Mineralization can be explained by a process of fluid–wallrock interaction with sulphidation and gold precipitation.

sPhysicochemical conditions of fluid–wall rock interaction at amphibolite-facies conditions in two Archean hydrothermal gold deposits in the Mt. York District, Pilbara Craton, Western Australia

1995 ◽  
Vol 32 (7) ◽  
pp. 993-1016 ◽  
Author(s):  
P. Neumayr ◽  
J.R. Ridley ◽  
D.I. Groves
Keyword(s):  
Western Australia ◽  
Gold Mineralization ◽  
Wall Rock ◽  
Gold Deposits ◽  
Iron Formation ◽  
Banded Iron Formation ◽  
Rock Interaction ◽  
Wall Rock Alteration ◽  
Geochemical Analyses ◽  
Pilbara Craton

Synamphibolite facies Archean gold mineralization in the Mt. York District, Pilbara Craton, Western Australia, is hosted in metamorphosed banded iron formation (Main Hill–Breccia Hill prospect), amphibolites, and ultramafic schists (Zakanaka prospect). Mineralization at Main Hill occurs in quartz breccias with sulfide matrices and in altered wall rock adjacent to quartz–biotite–amphibole ± clinopyroxene veins. Alteration associated with quartz veins is zoned, with biotite—pyrrhotite vein selvedges and a distal calcic-amphibole, arsenopyrite–lôllingite zone. Hydrothermal biotite and actinolite have highest Mg/(Mg + Fe) ratios where associated with abundant sulfarsenides in the distal alteratin zone. Whole-rock geochemical analyses and calculated metasomatic reactions indicate the addition of K, Al, S, As, Au, Ag, and Ni during hydrothermal alteration. Mineralization at Zakanaka is characterized by a broad wall rock alteration halo of biotite–amphibole, and zoned quartz–calc silicate veins proximal to ore. Wall rock adjacent to the veins contains pyrrhotite, pyrite, and gold. The alteration is explained by K-metasomatism distal to mineralization and K and Ca metasomatism proximal to mineralization. Balanced metasomatic reactions and mass-balance calculations indicate addition of K and depletion of Na, Ca, Mg, and Fe in distal alteration zones and addition of K, Ca, Mg, Fe, and Ti in proximal zones. Gold precipitation at both prospects occurred through loss of S, and possibly As, from the ore fluid during sulfidation reactions with Fe-rich amphiboles and biotites to form Mg-enriched equivalents and sulfarsenides. Changes in the oxidation state of the ore fluid may have enhanced gold precipitation, though pH changes are unlikely to have been important. The controls on mineralization are thus similar to those at many lower temperature, mesothermal deposits. The lack of consistently increasing Mg ratios of calc-silicate phases with increasing intensity of alteration and sulfidation at Main Hill may be the result of coupled substitutions in amphiboles and biotites during infiltration of a fluid with high-S, but low-As, activities.

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