Landform-regolith mapping in the West African context

Sawadogo, Boureima; Bamba, Ousmane; Chardon, Dominique

doi:10.1016/j.oregeorev.2020.103782

Cited by 7 publications

(4 citation statements)

References 33 publications

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“…In Eastern Adamaoua, rugged erosional terrains with average slope gradient of ~4 to 5 % between wide domains of pediplains (Fig. 1b) also portray hillslope erosion that preferentially occurred on inherited litho-structural discontinuities (see also Sawadogo et al, 2020). Landscape physical rejuvenation was also previously observed in western highlands of Cameroon (Momo Nouazi et al, 2019) on Mid-Miocene basalts and trachytes, and possibly occurred during a period (i.e., Pliocene) of mechanical (clastic) erosion (Tchouatcha et al, 2010).…”

Section: Landscape Erosion Signatures From the Composite Lateritic We...supporting

confidence: 56%

Erosion mode and history of Eastern Adamaoua landscapes (Cameroon): Superimposed lateritic weathering of granites and basalts

Momo

Beauvais

Nguemo

et al. 2023

CATENA

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Section: Landscape Erosion Signatures From the Composite Lateritic We...supporting

confidence: 56%

Erosion mode and history of Eastern Adamaoua landscapes (Cameroon): Superimposed lateritic weathering of granites and basalts

Momo

Beauvais

Nguemo

et al. 2023

CATENA

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“…Gold exploration in weathered and covered terrains commonly relies on analysing surface or shallowly collected soil samples that may or may not have a direct genetic relationship with the underlying basement. Comprehensive characterisation of the regolith landscape is required, especially regarding the relictual, erosional or depositional nature of the regolith surface (Butt et al, 2000;Arhin and Nude, 2009;Sawadogo, 2020). The distinction between in situ and transported material within deep weathering profiles may rely on several types of observation at different scales.…”

Section: Implications For Gold Explorationmentioning

confidence: 99%

“…When exposed, iron duricrusts may prove helpful for geochemical vectoring as the formation of lateritic residuum may lead to gold remobilisation and enrichment (Anand et al, 2019). Such an approach requires discriminating purely residual duricrusted surfaces (lateritic residuum; from duricrusts developed on glacis (ferricrete; Sawadogo et al, 2020) through field-based investigations, including regolith mapping and textural observations. Investigations conducted on the truncated, in situ deep weathering profile at Achman Giraud highlight no significant dispersion of gold from the mineralised veins in saprolite and lower mottled horizons, although the dispersion may be more pronounced in the overlying residual latosol.…”

Section: Implications For Gold Explorationmentioning

confidence: 99%

Diversity of supergene gold expressions and implications for gold targetting in an equatorial regolith (AMG's Couriège Exploration Prospect, French Guiana)

Combes

Teitler

Eglinger

et al. 2021

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The Couriège prospect (French Guiana) provides key examples of the diversity of gold distribution related to supergene processes. The nature of gold in two contrasted weathering profiles is examined as a function of the weathering lithofacies. The autochthonous profile hosts weathered Au-bearing quartz veins whereas the pediment profile is enriched in free gold issued from dismantled gold-bearing quartz veins. The gold distribution is controlled by: (i) the preservation of primary gold as free gold in both transported and autochthonous horizons and as electrum inclusions in detrital pyrite, and (ii) the formation of secondary gold through dissolution/precipitation processes, expressed as gold spherulites on free gold grain surface, Ag-depleted rim around transported free gold grains and Ag-depleted gold micro-inclusions hosted by oxidised autochthonous pyrite. Gold enrichment through supergene chemical processes remains limited within the truncated autochthonous profile. A new conceptual model is proposed for the area, defining the role of chemical and physical processes in gold endowment, and accounting for the geomorphological context. The overall evolution includes (i) deep weathering and peneplenation, (ii) dismantlement and transport of lateritic material, and (iii) development of a latosol cover. This study highlights that gold exploration in tropical environments must consider the residual vs transported nature and the inheritance of targeted pedogenic horizons.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5476187

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“…The exploration for gold in weathered and covered terrains commonly relies on sampling and analyzing in situ material [12]. A detailed characterization of the regolith is required in order to be er comprehend the physico-chemical changes along the profile and distinguish remobilized material from that developed in place [13,50,79,80]. The data presented in this study suggest that gold remained in the solid form during its dispersion, owing to its chemical stability.…”

Section: Implication To Gold Exploration In the Regolithmentioning

confidence: 89%

Soil Geochemistry Combined with Particulate Gold Microchemistry Provides Evidence of Eluvial Gold Genesis and Anthropogenic Hg Use in Eastern Cameroon Goldfields

Vishiti,

Suh,

Ngatcha

et al. 2024

Minerals

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The identification of trace element anomalies in soils has been proven to assist semi-mechanized small-scale gold operations. This study employs soil geochemistry combined with the microchemical signature of particulate gold from the Batouri goldfield to (1) vector possible gold-endowed lithologies introducing particulate gold into the overlying regolith, and (2) assess anthropogenic Hg used in purification of both primary and alluvial/eluvial gold by artisans. The soil geochemistry shows irregularly distributed anomalies of elevated Cu especially in the saprolite soil layer. Whereas in the lateritic soil layer, a Au-Ag-Hg metal association is reported for the first time in this gold district and could be linked to anthropogenic Hg used in gold recovery. Particulate gold recovered from the soil varies in shape from euhedral and irregular to sub-rounded, indicating a proximal lode source. The gold grains range in size from nano-particles to >300 µm and are Au-Ag alloys. The gold particles reveal inclusions such as quartz, silicate, zircon and ilmenite suggesting that the grains were dislodged from quartz veins within the granitic basement. Systematic variation in the microchemical signature of the gold grains is suggestive of spatial and temporal evolution of the mineralizing fluid. These results are consistent with investigations from similar geologic settings worldwide and validate the combined utility of gold fingerprinting and pathfinder elements in soil to examine deposit genesis in other gold districts globally.

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Landform-regolith mapping in the West African context

Cited by 7 publications

References 33 publications

Erosion mode and history of Eastern Adamaoua landscapes (Cameroon): Superimposed lateritic weathering of granites and basalts

Erosion mode and history of Eastern Adamaoua landscapes (Cameroon): Superimposed lateritic weathering of granites and basalts

Diversity of supergene gold expressions and implications for gold targetting in an equatorial regolith (AMG's Couriège Exploration Prospect, French Guiana)

Soil Geochemistry Combined with Particulate Gold Microchemistry Provides Evidence of Eluvial Gold Genesis and Anthropogenic Hg Use in Eastern Cameroon Goldfields

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