Endeavour now owning an 80% stake in the Lafigué project, with Société pour le Développement Minier de la Côte d’Ivoire (SODEMI) and the State of Côte d’Ivoire each owning a 10% stake.
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Summary:
The Lafigué deposit resembles a typical shear zone-hosted deposit of the West African Paleoproterozoic greenstone terrane (Man-Leo Shield) and can be associated with the low-sulphide quartz gold deposit model of Laurence J. Drew (Drew, 2003). The deposit is related to the N-S-trending Oumé-Fetekro greenstone belt, and more specifically, to a Birimian age complex of bimodal metavolcanics and meta-volcanoclastic rocks intruded by a series of felsic intrusions. Mineralization is spatially and genetically related to shearing and fluid ingress along zones of competency contrast between different lithologies. There is a further spatial relationship between some mineralization and felsic intrusive bodies. Gold is often free, occurring in quartz-carbonate-tourmaline veins or associated alteration haloes. Zones of shearing and alteration (mineralised or otherwise) can reach 10s of metres thick, pervading the hanging wall and footwall rocks away from recognised lithological contacts.
The Lafigué deposit is a shear-zone hosted gold mineralization, sitting on the eastern side of the Fetekro permit and extends over an area that is 2.2 km long and 1 km wide. The geology is mostly composed of mafic rocks, namely metagabbros/metanorites and metabasalts. A felsic intrusive (granodiorite or tonalite) occurs in the western part of the prospect and several felsic dykes possibly related to the principal body have been observed in various areas. Regional schistosity varies in strike from north to south to N70° with gentle to intermediate/steep dips to the east and south (25°- 65°).
The deposit is formed by a series of stacked mineralised lenses associated with a brittle-ductile shear zone slightly dipping to the SSE. Gold occurs mostly as free electrum within quartz-tourmaline-pyrrhotite-chlorite veins and veinlets.
The Lafigué mineralisation is primarily controlled by an east-northeast-trending brittle-ductile thrust fault dipping 15° to 45° south-southeast. Gold mineralisation occurs as a network of Quartz-Carbonate-Tourmaline-PyritePyrrhotite veins within sheared and altered brittle-ductile deformation zones of variable thickness. The alteration assemblage comprises Biotite-Sericite-Tourmaline-Chlorite-Carbonate and various amounts of disseminated Pyrite and Pyrrhotite (up to 5%). The shear zones show a typical C-S geometry, with the CS at some angle of the S (schistosity) fabric due to shearing. The veins are emplaced in the deformation corridors both along CS and S planes. The shear foliation and most of the veins dip shallowly to the south or south-southeast. QuartzCarbonate-Tourmaline-Pyrite-Pyrrhotite veins occur in the shear zones, show crack-seal textures or have a breccia texture with strongly altered xenoliths of sheared host rock. They appear to dilate the sheared SC foliation of the host rock at various stages of the shearing history, which demonstrate their syn-deformation emplacement (Ciancaleoni, 2018).
At Lafigué, a prominent deformation zone is typically located at the contact zone between a mafic intrusive (gabbro) and mafic volcanics, whereby the contact also occurs with a felsic intrusive at Lafigué North. The shear zones (and associated mineralisation) are better developed at or near lithological contact zones, where competency contrasts favour the localisation of brittle-ductile shearing with a permeability increase and enhanced hydrothermal fluid flow; however, these shear zones also appear in the core of massive intrusive or metavolcanic units.
Mineralisation is often hosted by quartz-carbonate-tourmaline-pyrite-pyrrhotite-gold veins as well as the associated biotite-tourmaline-sericite-chlorite-carbonate alteration zones, where these veins typically exploit the gently dipping brittle-ductile reverse shear zones. Although the quartz-tourmaline lodes commonly host mineralisation at the primary lithological contacts across the Lafigué project area, where quartz veins are barren or low grade, they can form planes of rheological contrast which have focussed auriferous fluids along vein contacts, mineralising the hanging wall or footwall rocks. Gold is also hosted within broader zones of altered, stacked shear zones in the hanging wall (and to a lesser degree, the footwall) of the main lithological contacts. In particular, the entire thickness of the granodiorite body in Lafigué Nord is often mineralised, including disseminated pyrite, pyrrhotite and gold, along with a similar alteration assemblage to that associated with the quartz lodes. In the broader zones of stacked shears, there is a tendency towards higher grades at the footwall contacts which likely accommodated the greatest strain and associated fluid flow.
Mineralization at Lafigué has been interpreted to have a strike length of approximately 2 km, trending eastnortheast and dipping moderately to the south-southeast. Mineralization has been intersected to depths of approximately 440 m below the surface in Lafigué North, which is approximately 700 to 900 m of down-dip extension. The continuity of the mineralization reduces towards Lafigué Centre and to the south and west. The deposit remains open at depth and, in some areas, along strike.