scholarly journals Hydrothermal alteration and vectors at the orogenic Island Gold deposit, Michipicoten Greenstone Belt, Wawa, Ontario

2018 ◽  
Author(s):  
T J Ciufo ◽  
C Yakymchuk ◽  
S Lin ◽  
K Jellicoe ◽  
P Mercier-Langevin
Keyword(s):  
Gold Deposit ◽  
Hydrothermal Alteration ◽  
Greenstone Belt

scholarly journals Geology, structural evolution, and hydrothermal alteration of the Island gold deposit, Michipicoten greenstone belt, Ontario

2020 ◽  
Author(s):  
T J Ciufo ◽  
K Jellicoe ◽  
C Yakymchuk ◽  
S Lin ◽  
P Mercier-Langevin ◽  
...  
Keyword(s):  
Gold Deposit ◽  
Hydrothermal Alteration ◽  
Greenstone Belt ◽  
Structural Evolution

Hydrothermal Alteration Mineralogy and Geochemistry of the Archean World-Class Canadian Malartic Disseminated-Stockwork Gold Deposit, Southern Abitibi Greenstone Belt, Quebec, Canada

2019 ◽  
Vol 114 (6) ◽  
pp. 1057-1094 ◽  
Author(s):  
Stéphane De Souza ◽  
Benoît Dubé ◽  
Patrick Mercier-Langevin ◽  
Vicki McNicoll ◽  
Céline Dupuis ◽  
...  
Keyword(s):  
Gold Deposit ◽  
Fault Zone ◽  
Hydrothermal Alteration ◽  
Greenstone Belt ◽  
Gold Mineralization ◽  
Amphibolite Facies ◽  
Alteration Zone ◽  
Gold Deposition ◽  
Abitibi Greenstone Belt ◽  
World Class

Abstract The Canadian Malartic stockwork-disseminated gold deposit is an Archean world-class deposit located in the southern Abitibi greenstone belt. It contains over 332.8 tonnes (t; 10.7 Moz) of Au at a grade of 0.97 ppm, in addition to 160 t (5.14 Moz) of past production (1935–1981). Although the deposit is partly situated within the Larder Lake-Cadillac fault zone, most of the ore occurs up to ~1.5 km to the south of the fault zone. The main hosts of the mineralized zones are greenschist facies turbiditic graywacke and mudstone of the Pontiac Group (~2685–2682 Ma) and predominantly subalkaline ~2678 Ma porphyritic quartz monzodiorite and granodiorite. These intrusions were emplaced during an episode of clastic sedimentation and alkaline to subalkaline magmatism known as the Timiskaming assemblage (<2680–2670 Ma in the southern Abitibi). The orebodies define two main mineralized trends, which are oriented subparallel to the NW-striking S2 cleavage and the E-striking, S-dipping Sladen fault zone. This syn- to post-D2 ductile-brittle to brittle Sladen fault zone is mineralized for more than 3 km along strike. The ore mainly consists of disseminated pyrite in stockworks and replacement zones, with subordinate auriferous quartz veins and breccia. Gold is associated with pyrite and traces of tellurides defining an Au-Te-W ± Ag-Bi-Mo-Pb signature. The orebodies are zoned outward, and most of the higher-grade (>1 ppm Au) ore was deposited as a result of iron sulfidation from silicates and oxides and Na-K metasomatism in carbonatized rocks. The alteration footprint comprises a proximal alteration envelope (K- or Na-feldspar-dolomite-calcite-pyrite ± phlogopite). This proximal alteration zone transitions to an outer shell of altered rocks (biotite-calcite-phengitic white mica), which hosts sub-ppm gold grades and reflects decreasing carbonatization, sulfidation, and aNa+/aH+ or aK+/aH+ of the ore fluid. Gold mineralization, with an inferred age of ~2664 Ma (Re-Os molybdenite), was contemporaneous with syn- to late-D2 peak metamorphism in the Pontiac Group; it postdates sedimentation of the Timiskaming assemblage along the Larder Lake-Cadillac fault zone (~2680–2669 Ma) and crystallization of the quartz monzodiorite. These chronological relationships agree with a model of CO2-rich auriferous fluid generation in amphibolite facies rocks of the Pontiac Group and gold deposition in syn- to late-D2 structures in the upper greenschist to amphibolite facies. The variable geometry, rheology, and composition of the various intrusive and sedimentary rocks have provided strain heterogeneities and chemical gradients for the formation of structural and chemical traps that host the gold. The Canadian Malartic deposit corresponds to a mesozonal stockwork-disseminated replacement-type deposit formed within an orogenic setting. The predominance of disseminated replacement ore over fault-fill and extensional quartz-carbonate vein systems suggests that the mineralized fracture networks remained relatively permeable and that fluids circulated at a near-constant hydraulic gradient during the main phase of auriferous hydrothermal alteration.

Mineralization and hydrothermal alteration in the Mamão orogenic gold deposit, Andorinhas greenstone belt, Carajás Province, Brazil

2021 ◽  
pp. 103548
Author(s):  
Sebastião Rodrigo Cortez de Souza ◽  
Nilson Francisquini Botelho ◽  
Federico Alberto Cuadros Jiménez ◽  
Elton Luiz Dantas ◽  
Mateus Andrade Reis ◽  
...  
Keyword(s):  
Gold Deposit ◽  
Hydrothermal Alteration ◽  
Greenstone Belt ◽  
Orogenic Gold ◽  
Orogenic Gold Deposit ◽  
Carajás Province

The Yatela gold deposit in Mali, West Africa: The final product of a long-lived history of hydrothermal alteration and weathering

2016 ◽  
Vol 113 ◽  
pp. 73-87 ◽  
Author(s):  
Quentin Masurel ◽  
John Miller ◽  
Kim A.A. Hein ◽  
Eric Hanssen ◽  
Nicolas Thébaud ◽  
...  
Keyword(s):  
West Africa ◽  
Gold Deposit ◽  
Hydrothermal Alteration ◽  
History Of

The Karouni Gold Deposit, Guyana, South America: Part II. Hydrothermal Alteration and Mineralization

2018 ◽  
Vol 113 (8) ◽  
pp. 1705-1732 ◽  
Author(s):  
Michael Tedeschi ◽  
Steffen G. Hagemann ◽  
Malcolm P. Roberts ◽  
Noreen J. Evans
Keyword(s):  
South America ◽  
Gold Deposit ◽  
Hydrothermal Alteration

Geological evolution of the Manitouwadge greenstone belt and Wawa-Quetico subprovince boundary, Superior Province, Ontario, constrained by U-Pb zircon dates of supracrustal and plutonic rocks

1999 ◽  
Vol 36 (6) ◽  
pp. 945-966 ◽  
Author(s):  
Eva Zaleski ◽  
Otto van Breemen ◽  
Virginia L Peterson
Keyword(s):  
Hydrothermal Alteration ◽  
Greenstone Belt ◽  
Boundary Region ◽  
Detrital Zircons ◽  
Ductile Deformation ◽  
Superior Province ◽  
Geological Evolution ◽  
Hydrothermal Alteration Zones ◽  
Depositional Age ◽  
East West

Fifty million years of Archean evolution is recorded in the Manitouwadge greenstone belt and the Wawa-Quetico boundary region, from ca. 2720 Ma volcanism and subvolcanic plutonism associated with massive sulphide deposits and hydrothermal alteration zones, to 2689-2687 Ma and 2680-2677 Ma synkinematic plutonism. In the greenstone belt, greywackes were deposited after 2693 Ma, post-dating local volcanism by at least 25 Ma, and requiring that the volcanic-sedimentary contact is an unconformity or a fault. In migmatitic greywackes in the Quetico subprovince, detrital zircons limit the depositional age to <2690 Ma, permitting correlation of greywackes across the Wawa-Quetico subprovince boundary. Upward-facing inclined F2 folds that deform the volcanic-sedimentary contact are bracketed by the 2687 ± 2 Ma Loken Lake pluton, which shows strong D2 fabrics, and by 2680+4-3 Ma foliated granite which cuts D2 fabrics. Dextral transpression producing regional F3 folds and the overall east-west trends of the Wawa-Quetico boundary region post-dated the 2680 ± 2 Ma Nama Creek pluton. Field relationships and isotopic ages support correlation of greywackes across the subprovince boundary, and demonstrate that most or all of the ductile deformation post-dated sedimentation. Ductile structures, especially those associated with dextral transpression, are not directly related to juxtaposition of the Wawa and Quetico subprovinces, as these were already contiguous, either through sedimentation on a volcanic substrate or as a result of earlier cryptic structures. Our results imply that the belt-like configuration of the subprovinces, emphasized in accretionary models of the Superior Province, is a relatively late feature that overprints older, tectonically significant structures.

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