Adjacent to Avocet Mining’s Inata 4.6 Million Oz Gold Deposit
Regionally Avocet Mining’s (LON:AVM) Inata Gold Deposit’s 4.6 million ounces is part of the Bélahouro group of licences and is located in the western portion of the Djibo Birimian Greenstone Belt. The belt comprise of intermediate to mafic volcano sedimentary successions and syn to post-kinematic granite and gabbro intrusions that has undergone regional lower greenschist metamorphism and lately intruded by dolerite and felsic- porphyry rocks.
The Inata Gold Deposit is localised within a NS-striking shear zone with an overall strike extent of 6 kilometres from Inata North to Inata Far South with additional sub-parallel shears hosting ore bodies in the eastern footwall at the northern end (Sayouba extending 350m). The southern Minfo East West trend is now extending (trend now extends) over 1.5 km from main Minfo main to Minfo East and continues further East with the Filio and Ouzeni trend.
The shear zone is localised within a steeply dipping, foliated and isoclinally-folded sequence of carbonaceous shales sandwiched between similarly foliated mafic volcanic rocks and noncarbonaceous siltstones.
The zone of shearing is intruded by fine-grained quartz-feldspar porphyry dykes that have been emplaced during the mineralising event, as evidenced by the shearing of some porphyries and the stoping of shear veins by the intrusions. Dyke widths are highly erratic from centimeters to meters wide and are oriented along the shear structure and in flat zones cutting across the shear. Graphitic shears have been mapped striking parallel to the shear zone. Gold mineralisation is commonly associated with sheeted and sheared quartz–carbonate–sulphide veining, albite-carbonate-sulphide veinlets and extensional quartz-sulphide veins. Earlier quartz-carbonate veins can be boudinaged, folded, or brecciated. Gold is also associated with sulphide-haematite breccia. There are two main structural directions that control gold mineralisation; steep west dipping NNE-SSW trending faults and flatter NE-SW trending bedding directions.
Gold is present as free grains and inclusions in pyrite disseminated in the alteration halo around quartz-carbonate-albite veins. Pyrite is the dominant sulphide present as veins, fracture fillings and localized disseminations adjacent to veins although minor amounts of chalcopyrite, galena, pyrrhotite, arsenopyrite, bornite, and tennantite are also present. Gold associated with pyrite is largely developed within fractures in pyrite grains, rarely larger than 50 microns, and is non-refractory.
The gold resource estimate for the Inata area is summarized in Table 4 shown below. The estimate was based on a cut off of 0.5 gram per tonne gold and was prepared in accordance to the JORC code 2004 edition.
TABLE 6 – Inata Mineral Resources
|Area||Category||Tonnes (MT)||Gold grade|
The foregoing geologic descriptions were taken almost verbatim from “Competent Persons Report (CPR) Avocet Mining PLC West African Projects Burkina Faso and Guinea” prepared by G. Fahey FAusIMM, MAIG, K.Bannister ARMIT, FAusIMM (CP), T.Gibbons FAusIMM (CP) dated September 27,2013.