The Benkanto Seekoto Mining Concession’s area is located on the boundaries of three perimeters operating independent Gold operations referred to respectively ‘ NGARI, ‘ NGARI – SEEKOTO ‘ and ‘ TINKOTO-SOU. These three sites are located at approximately 15 km to the Northwest of Kedougou and cover a total area of 150 HA divided into 50 hectors each. They are defined by the points of coordinates, of UTM WGS 84 p28.
(Fig. 2, 3)
The Perimeter of NGARI : (GIE BENCOUTOU)
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The Perimeter of TINKOTO SOU: (GIE SINING KANG)
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The Perimeter of NGARI SEEKOTO : (GIE BENKANTO)
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The prospecting work was carried out essentially (to more of 80%), in the two perimeters WHICH are TINKOTO SOU and NGARI SEEKOTO and the results of the geochemical testing produced high grades of gold and the areas anomalous, identified.
Fig. 2: Map location of perimeters of prospecting, scale 1 : 100 000.
Fig.3 : Map of the Perimeters that were prospected, scale 1 : 50 000
. Geological and tectonic context
The work of BALOCH (1963, 1966, 1987) has permits to subdivide the training birrimiennes of Eastern Senegal in two super groups willing in bands elongated NNE – SSW with West in (Fig.4, 5) :
The Super Group of Mako has dominant volcanic associated with plutonic and hypo volcanic and inter laminates together with a volcano – detrital to sedimentary. The Super Group of world Dalema has dominant sedimentary formed from training detrital and sillico-carbonate, which has been cut by a volcanic intermediate and is very developed. These formations are associates of the granite supracrustal flush under form of batholiths composites. It is batholiths of Kakadian and from Saraya, put in place respectively in the of super groups of Mako and training World – Dalema. An importance aspect is the presence of granites post-tectonic Calc – alkaline (Tinkoto, Sambarabougou, Mamakhono, Soukouta, etc.), with their processions dykes , which the development place seems intimately related to the process hydrothermal of training the mineralization Gold primary. Perimeters are found in outskirts is of Super Group of Mako. It constitutes the Western part of the button half of Kedougou – Kéniéba region.
Table 4 : estate of sequences litho-structural of super Group of Mako, from the mission Soviet (1972 – 1973).
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Fig. 4: Geological Map and Diouras, Pasmi 2008.
The area of exploration is set in the limit of the anticlinorium from Mako. The limits of this anticlinorium are set to go in areas of faults abyssal :
West is the area of faults deep bordering the shear area of Sabodala where anticlinorium of Mako has a contact tectonics with the batholith of Kakadian. The East, is the area of faults abyssal that fixed the edge West of synclinorium world. The width total of the anticlinorium is estimated at more than 25 Km; its length, after the outcrops of the series of Mako on the geological map, fact more of 60 Km.
Fig. 5 : Context geological perimeters of prospecting, extract of the map to the 1 : 200 000.
This sector, distinguishes three main groups faults:
The faults syntectonic birrimiennes that border main megastructures folded such that the fault components corridors of deformations of Sabodala, Khossanto and World ; These faults are often staked by a dykes of Gabbro, Diorite, porphyry quartz or albitite. The faults post tectonic (post orogenic) sublatitudinales or NW (120 – 160 °), often met by of breccia silicified and sulphurized (oxidized en surface) and of quartz Lode. These areas of faults are very visible on the aerial, photos than that on the ground. Morphologically, they represent a series of sub-parallel faults of shear and opening, which the extensions individual vary of some hundreds of meters to 6 Km in general. The concentration (density) of these faults is much more forte in the areas d’ expansion ofs granite post – tectonic (Mako, Tinkoto, Falombo, Mamakhono, Dendifa, Sambarabougou, etc.), fact which allows to assume a link genetics likely between these structures tectonic and magmatic with the mineralization gold.
In effect, in the limits of area influence of faults post – orogenic NW, especially in limit of the rocks competent such that the diorites, on note very often the development network relatively dense of vein metric to UHF of quartz, quartz – tourmaline, quartz-carbonate accompanied by their processions of Stringer centimetre to millimetre directions and from dips, that can be assimilated to real shears areas or stock works. The faults relatively recent and local, scope limited, which in the most of time complicate the structures cited, in the winning. The long of these accidents tectonic is observed often an amplification of process of remobilization secondary oxidation, and of leaching in the parties little deep of the under – floor.
Features geological and mineralogical.
The sector is located in the limits of a wide corridor of direction deformation, birimian, parallel to that some areas of depth of Sabodala faults. In the Interior of this corridor, is developed with shears-areas, made of veins and Stringer quartz, of different sizes and directions. Area of conjunction of three perimeters is a plain lateritic alluvial and eluvionnaire, where is provided, observe pieces and block vein and Stringer dismantled and decayed.
The study mineralogical, made of the Gold ore by the Pasmi support to gold panning and the laboratory of Director of Mines and of Geology, had obtained the following results:
- The ore Gold is from nature per whitish, greyish, pinkish to Brown.
- It is composed mainly quartz, chlorite, oxides and hydroxides of railway and carbonate.
- content of gold total for the sample analysis by the PASMI was of 4.82 g/t, so than that of different fractions particle size, varied between 1.99 and 15,22 g/t.
- The and crushing the spray of ore quartz had passes without constraint notable. Well that quartz be in general hard and abrasive, the development systems of cracking (microtectonic) in the ore, reduces significantly the efforts of grinding.
Estimation of Resources Probable Gold
A. Resources Gold vein
We have made the estimates of Gold resources only in the area covered by the work exploration by trench and wells, approximately 40% of the surface total of 3 perimeters. The main vein areas taken in account for the calculations, are included in the tables below (table 13 and 14).
Table 13 : Calculation of the surface of vein areas
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Table 14: Estimates of gold resources, next depth
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Formula used : Surface x depth x 2.4 (density of quartz) x content average.
The quantity of Gold vein resources estimated on the base of the interpretation of information collected in the trenches rises to the total to 545,554 Kg.
Gold resources eluvionnaires
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The global Gold resources estimated on the basis of results of analysis and interpretation of two phases of prospecting, amounted to 680,554 Kg .
Potential Real Gold must surely widely exceed this Figure, given that the study area represents approximately 40% of the total surface of 3 perimeters strategy and that the many Stringer Gold centimeter at millimeter are not taken into account unlike evaluation of resource gold.
In table 16, below, is the quote from the campaign of prospecting. Table 16 : quote of the exploration (Phase II).