The Kekoro area is the most extensively explored of all the Medoro licence areas. The area was explored by the Japanese International Cooperation Agency (JICA) and the Metal and Mining Agency of Japan (MMAJ) from 1991 to 1999 together with the Malian Direction Nationale de la Geologie et des Mines (DNGM). Subsequent infill soil sampling was completed over the area and identified a strong continuous gold soil anomaly in the northern part of the property (the Kekoro A/F target) with values consistently over 100 ppb gold. Further work included Landsat satellite image interpretation and a regional soil sampling program.
In 1998-9, detailed geological mapping was conducted over the target area in the north of the licence. The results revealed a package of metasedimentary units intruded by granodiorite and later dolerite, with the top of the hill composed of an interpreted roof pendant of sediments. A program of sampling then took place within this target area, with 48 ancient artisanal orpillage pits sampled. Results varied from 0.1 to 86 grams per tonne of gold, with mineralised intercepts associated with quartz veins and felsic intrusives. The sampling programme was followed by the drilling of 66 RC holes (4,205 metres in total) and 11 diamond holes (1,800 metres in total). An induced polarization survey was also completed over the same target area, with a total of 13.5 km/lines. Between 2000 and 2004, the property was held by the Japanese company Overseas Mineral Resources Development (OMRD), who completed a gamma ray survey in an attempt to identify the sediment-granodiorite contact. A further drilling program was undertaken to the west of the main target area, with five diamond drill holes (1600 metres in total), RAB drilling (3500 metres in total) and soil geochemistry (2300 samples). None of the methods identified any gold mineralisation. In 2002, OMRD established a joint venture with Randgold Resources to explore the Kekoro area and the bordering zones. Randgold acquired and reprocessed the JICA archive and completed some new soil lines. Randgold also partially followed up with rock chip sampling at three other target areas (the Bagoe River targets), located on the western edge of the present licence. Anomalous values ranging from 0.41 to 41.7 grams per tonne of gold were identified in association with felsic dykes, which are part of the granodioritic magmatic cycle present in the northern sector. The project was dropped in 2004, after Randgold did not find evidence of a Morila-style deposit. The remains of the OMRD camp are still present immediately to the north of the village of Kekoro, to the east of the licence area itself.
There has been no commercial production of gold from the area; however, artisanal workings are present within the property boundaries. In the northeastern part of the licence area, artisanal workings can be observed on the edge of the granodiorite-dolerite hill. The workings straddle the side of the hill, including the area around the site of JICA drill holes KDD4, 5 and KRC48 and down into the valley. The pits are round, approximately 1 m in diameter, and appeared to be exploiting the clay zone as very few bedrock fragments were present within the excavated material.
The Kekoro licence area is located within the Bougouni region of the West African craton, where generally north-south trending belts of Birimian metavolcano-sedimentary and metasedimentary rocks and orogenic granitoids of Early Proterozoic age crop out. The trend of the major structures is northsouth and northeast-southwest, which are related to transcurrent D2 and D3 deformations. The majority of the licence area is covered by Birimian meta-volcano-sedimentary rocks, comprising greywackes, siltstones, conglomeratic volcano-sediments and intercalated schists. The sediments have been intruded by granites, granodiorites and felsic dykes. One such intrusion of granodiorite is present in the northern sector of the property. This was mapped in detail during the JICA exploration program in the late 1990s. The sedimentary units, metamorphosed to graphitic shales, are folded into a series of isoclinal folds. The mapping also suggests the presence of a roof pendant of sediments, which currently makes up the summit of the small topographic hill in the area. In the western part of the property, drilling by Randgold identified a number of felsic porphyry intrusives, related to the episode of granodiorite intrusion. These were also found to occupy the axial planes of isoclinal folds within the volcano-sedimentary units. There are a number of Mesozoic dolerite sills and dykes, which form prominent ridges that form a circular topographic feature which the licence area covers the eastern half of the Sindo area.
The property has been quite extensively explored over the past 10 years by DNGM, JICA and OMRD, with exploration activities including soil surveys, IP surveys, geological mapping, drilling and Landsat interpretation.
In 1998-9 JICA drilled 66 RC holes (4,205 metres in total) and 11 diamond holes (1,800 metres in total). The drilling revealed 22 mineralised sections with gold grades of 1 gram per tonne or more over several metres. The highest grade interval was a 1 metres section at 19.95 grams per tonne, and the thickest mineralised interval was 35 metres at 2.23 grams per tonne. The mineralisation was associated with the contact between the granodiorite and the metasediments within isoclinal fold structures and in the saprock above such structures.
A further drilling program was undertaken in 2000-2001 by OMRD, with five diamond drill holes (1600 metres in total) over an IP anomaly to the west of the Kekoro A/F target drilled. The results did not return any gold mineralisation. In the same period, three diamond drill holes were drilled on the Kekoro F target, which revealed an interval of 10 metres @ 0.6-1.0 grams per tonne of gold in each of the holes at different depths, with a further three intersects in one hole at 2 metres @ 2.1, 3 metres @ 3.7 and 4.7 metres @ 1.6 grams per tonne of gold.
The Kekoro licence area is bounded to the north and the east by research permits held by Moro Sarl. To the south, on the eastern half of the southern boundary, the research permit for the Dionkala licence area is held by New Mining. On the western half of the southern edge and the entire western edge of the Kekoro licence area, the property is bordered by the Kougourouna East licence area, the research permit for which is held by Barrick Gold Corporation. The multi-million ounce Morila mine, owned by Randgold (40%), AngloGold Ashanti (40%) and the Republic of Mali (20%) is located 30 km southeast of Kekoro. It is hosted by a similar package of Birimian volcan-sedimentary rocks intruded by granites, granodiorites and monzogranites that are present in the Kekoro licence area. Morila is a mesothermal shearzone-hosted deposit and mineralisation is characterised by silica-feldspar alteration and sulphide mineralisation including arsenopyrite, pyrrhotite, pyrite and chalocopyrite. In 2005, the Morila mine produced 650,000 oz of gold.
The Kekoro South licence is located within a large zone of Birimian metagreywackes and metasediments, with a number of dolerite bodies that form a circular physiographic feature across the licence area and to the east. In addition, there is a body of granodiorite in the northern part of the licence area. In terms of mineralisation, the Kekoro South area differs from most of the other licence areas in that gold is present as disseminations located at fold axes and is hosted by, or is proximal to, granodioritic stocks. Mesothermal lode quartz vein systems, characteristic of the other areas, are also present. Five types of mineralisation have been identified and include disseminated arsenopyrite and pyrite in volcano-sediments, disseminated pyrite in granodiorite, arsenopyrite and pyrite in strong calc-silicate alteration zones, the contact between felsic porphyry and granodiorite or sediments, and quartz veins. The mineralisation style and host rock lithologies are similar to that at the nearby Morila mine. The mineralisation appears to be concentrated at the apexes of isoclinal folds within the metasediments, in close proximity to the granodiorite stock. The granodiorite is associated with elevated gold value, with values constantly greater than 100 ppb. This is considered to make the granodiorite a likely source of gold in the system, particularly in the disseminated deposits around the contact between the granodiorite and the folded metasediments. Previous drilling work has identified a number of well mineralised intercepts, with 22 intersections in the holes drilled by JICA containing gold grades greater than 1 g/t over several metres. This known mineralisation, plus the known current artisanal production and the anomalous soils, make the area around the granodiorite in the northern part of the licence area particularly prospective (the Kekoro A/F target). However, there have been several exploration programs that have concentrated on this area without progressing to a production stage. Randgold dropped the licence after it failed to find a Morila-type deposit. Preliminary targets are the Kekoro A/F zone around the granodiorite, the Bagoe River anomalies and the other gold soil anomalies included within the dolerite "circle".