Regolith mapping and gold geochemical anomalies in the Siguiri Gold Mine of AngloGold Ashanti, Guinea, West Africa
- Authors: Bah, Boubacar
- Date: 2015
- Subjects: AngloGold Ashanti Ltd. , Regolith -- Guinea -- Siguiri (Region) , Gold mines and mining -- Guinea -- Siguiri (Region) , Geochemical surveys -- Guinea -- Siguiri (Region) , Soil surveys -- Geochemical methods -- Guinea -- Siguiri (Region) , Kriging
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5090 , http://hdl.handle.net/10962/d1019878
- Description: Gold exploration in the laterite terrains of the Siguiri basin (Guinea-West Africa) is discussed in this thesis. It seeks to propose and develop effective and reliable geochemical exploration techniques applied in such laterite terrains. The study is also intended to investigate and provide some geological clues as to why, in some target areas, the reconnaissance test drilling across the geochemical anomalies couldn’t intersect economic gold mineralisation. Targets were generated based on soil geochemical results, some of which were drilled without delivering economic discoveries even on areas with strong and consistent geochemical signatures. To find the failure and define the appropriate methods to be used is the core of the thesis. More importantly, the geological observation is aimed at sourcing and establishing the nature and validity of geochemical anomalies within the license area and their relationship with the underlying lithologies and structural networks. The geological field work conducted during this study is mostly based on regolith and surface geological mapping. The thick laterite cover, deep weathering, bedrock geology, gold geochemistry (the gold geochemical anomalous results are defined according to historical data before 2007), soil formations and variations in climate conditions are emphasized to illustrate the importance of mineral element mobility and dispersion in the weathering profiles. The knowledge and experience in regolith geochemistry and regolith mapping provide the advantage to exploration geologists. The depletion of ore resources and reserves in Siguiri and the continuous decline of the gold price in comparison to the complexity of exploring for gold are demanding more scientific-related thoughts and techniques to be integrated in the available geological, geochemical and geophysical information so as to reduce costs. The integration of good exploration strategy and technique may result in the possibility of making viable discoveries in this highly competitive geological environment where the mineral resources become depleted every day.
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- Date Issued: 2015
Structural controls of gold mineralisation in Seguelen pit of Siguiri gold mine, Guinea
- Authors: Beavogui, Massa
- Date: 2015
- Subjects: AngloGold Ashanti Ltd. , Gold mines and mining -- Guinea -- Siguiri (Region) , Geochemical surveys -- Guinea -- Siguiri (Region) , Geology, Structural -- Guinea -- Siguiri (Region) , Faults (Geology) -- Guinea -- Siguiri (Region) , Folds (Geology) -- Guinea -- Siguiri (Region) , Turbidites -- Guinea -- Siguiri (Region) , Metamorphism (Geology) -- Guinea -- Siguiri (Region) , Hydrothermal alteration -- Guinea -- Siguiri (Region)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5091 , http://hdl.handle.net/10962/d1019879
- Description: The present study provides the results of detailed mapping and analysis of structures encountered in Seguelen pit of Siguiri gold mine, Guinea, where the Siguiri mine is geo-tectonically located in the Baoulé-Mossi domain of Man Shield in West African craton. The gold deposit is hosted in low-grade metamorphic sediments of turbidites sequences which form part of the Lower Proterozoic of Birimian Super group. Three rock formations of Balato, Fatoya and Kintinian underlay the overall pits. The Siguiri gold mine is characterized by the deep weathering profile, developed over the rocks reaching 200 m below the surface in some areas and often capped by the lateritic gravel or duricrust. The rock formations at Seguelen area are characterised by strong bedding monotonously dipping towards SW and trending NW-SE. The lithology of the host rocks has strong control on the disseminated mineralisation throughout the deposit. Two domains of rock formations are clearly distinguished at Seguelen: Fatoya Formation(Ffm) domain ; and Kintinian Formation (Kfm) domain. The two domains are separated by a contact zone of 1.7 m wide parallel to bedding and characterised by the presence of quartz fragments as well as thinly sheeted shale and black shale. This contact zone is identified as disconformity. The major tectonic deformation which has affected the region is known as D2 corresponding to the Eburnean orogeny. The major D2 related structures is the regional thrust striking N-S over an area of 12 km long and 3 km wide and within which corridors all Siguiri gold Mine open pits are located. In the N-S trending structures, there is east-northeast shortening and north-northwest extension. There is pervasive hydrothermal alteration (carbonatization and sideritization) and supergene alteration in the all pits. The hydrothermal alteration attests the intensity of hydrothermal fluid-flow over the host rocks. The hydrothermal fluids flowed along the fractures and within the wall rocks through bedding plans to form numerous auriferous quartz veins bearing disseminated sulphides through chemical reaction between fluids and wall rocks, which are remarkable at Seguelen pit. Three quartz vein sets are distinguished at Seguelen: NNE-SSW quartz vein set NE-SW quartz vein set NW-SE quartz vein set The NE-SW and NNE-SSW quartz veins are often lenticular and associated with the bulk mineralisation.
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- Date Issued: 2015