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GEOREF RECORD

The Alamoutala carbonate-hosted gold deposit, Kedougou-Kenieba Inlier, West Africa

Quentin Masurel, Nicolas Thebaud, John Miller, Stanislav Ulrich, Malcolm Peter Roberts and Didier Beziat
The Alamoutala carbonate-hosted gold deposit, Kedougou-Kenieba Inlier, West Africa
Economic Geology and the Bulletin of the Society of Economic Geologists (January 2017) 112 (1): 49-72

Abstract

The Alamoutala gold deposit is located in the Kedougou-Kenieba inlier, a window of Paleoproterozoic rocks that crop out in eastern Senegal and western Mali. The deposit is part of the approximately 3-Moz Au Yatela district and produced 308,400 oz Au between 2002 and 2012. Country rocks in the Alamoutala open pit consist of carbonate rocks, arenites, wackes, and siltstones. The sedimentary rocks have been subjected to polycyclic deformation and regional greenschist-facies metamorphism. Synkinematic, calc-alkaline, intermediate quartz-feldspar porphyry stocks intruded the metasedimentary rocks at 2083 + or - 7 Ma (U-Pb zircon). Amphibolite-facies contact metamorphism of carbonate rocks resulted in the formation of a high-temperature-low-pressure magnetite-bearing skarn. Field relationships and microtextural data, however, indicate that economic gold mineralization is shear hosted and occurred during retrograde contact metamorphism. Geometric and kinematic analyses indicate that the ore-hosting structures were undergoing sinistral-reverse displacement at the time of mineralization. Ore minerals deposited synchronous with a potassic hydrothermal alteration assemblage defined as biotite + calcite + pyrite + or - K-feldspar, actinolite-tremolite, quartz, muscovite, and tourmaline. Petrographic studies reveal that ore-related sulfides largely consist of pyrite with lesser pyrrhotite and chalcopyrite. The ore also contains accessory Ag-Sb-As-Hg-Bi-Te-Mo-W-Zn-Pb-Ni-Co-U-bearing mineral species. The Alamoutala deposit represents two distinct hydrothermal systems in which a locally developed magnetite-bearing skarn was overprinted by a region-wide orogenic gold event in the late Eburnean.


ISSN: 0361-0128
EISSN: 1554-0774
Coden: ECGLAL
Serial Title: Economic Geology and the Bulletin of the Society of Economic Geologists
Serial Volume: 112
Serial Issue: 1
Title: The Alamoutala carbonate-hosted gold deposit, Kedougou-Kenieba Inlier, West Africa
Affiliation: University of Western Australia, Centre for Exploration Targeting, Crawley, West. Aust., Australia
Pages: 49-72
Published: 201701
Text Language: English
Publisher: Economic Geology Publishing Company, Lancaster, PA, United States
References: 68
Accession Number: 2017-023314
Categories: Economic geology, geology of ore deposits
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sect., 3 tables, geol. sketch maps
N12°15'00" - N14°15'00", W12°30'00" - W11°00'00"
Secondary Affiliation: CSIRO, Australian Resources Research Centre, AUS, AustraliaAngloGold Ashanti, AUS, AustraliaLaboratoire Geosciences Environment Toulouse, FRA, France
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Society of Economic Geologists. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201715
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