The Dandoko Project covers 134km2 within the Kenieba Inlier of west Mali in close proximity to numerous world class gold deposits including B2Gold’s 5.15Moz Fekola gold project 30km to the west and Randgold’s 12.5Moz Loulo Gold Mine 50km to the north-northwest.
Dandoko is underlain by Proterozoic Birimian meta-volcanic and meta-sedimentary sequences. A series of dominant NNE-trending faults, displaced by a second set of ESE-trending faults, have been mapped or interpreted from aeromagnetic data. Oklo considers that the NNE-trending structures are splays emanating from the Senegal-Mali Shear Zone (â€œSMSZâ€), a regional NNW-trending strike-slip fault that plays an important role in controlling gold mineralisation in the region. The SMSZ is extensively mineralised and hosts no fewer than six major gold deposits for an endowment estimated at greater than 40Moz, including Sadiola (13.5Moz) and Loulo (12.5Moz).
Previous exploration work in the area, largely undertaken by Compass Gold Corporation from 2010 to 2012, comprised mapping, soil sampling, pitting and trenching, which together with the commissioning of an airborne magnetic and radiometric survey, delineated a number of prospects.
Reconnaissance reverse circulation (â€œRCâ€) drilling in late 2013 and early 2014 provided strong encouragement and the Company completed a further 73 aircore (â€œACâ€) holes during 2015 testing multiple targets at the Disse, Selingouma and Diabarou prospects with considerable success. Detailed RC and diamond core drilling has been ongoing during 2016 with the primary objective of outlining an open pit resource at Diabarou.
The Diabarou gold-in-soil anomaly covers an area of 1.2km north-east x 1.0km east-west. Artisanal workings within the northern portion of the anomaly have revealed gold-bearing quartz veins of up to 3m in thickness extending over 600m.
Previous drilling was restricted to the fringes of the artisanal workings and returned significant intersections of 12m at 1.50g/t gold and 20m at 1.44g/t gold in 2013. A total of 45 in-situ samples collected from the base of the artisanal workings returned numerous high grade gold results (up to 68.3g/t gold).
Further RC drilling of the artisanal workings commenced in late 2015 and to date has returned several outstanding intersections, including:
- 29m at 10.42g/t gold;
- 6m at 53.77g/t gold;
- 3m at 110.3g/t gold;
- 28m at 3.90g/t gold;
providing support for the prospect’s open pit potential.
The gold mineralisation at Diabarou is hosted in a sequence comprising volcaniclastic tuff and graphitic greywacke intruded by diorite and dolerite. The mineralised zones correspond with extensive brecciation and hydrothermal alteration associated with an interpreted fault structure.
Two phases of alteration are observed. An early phase comprising sericite-silica-pyrite-hematitic carbonate and a later phase characterised by quartz-carbonate-pyrite-arsenopyrite-albite-tourmaline associated with visible gold. The earlier phase of alteration has similar assemblages to those observed and documented at the nearby significant gold discoveries of Gounkoto and Fekola, which are located approximately 40km northwest and 30km west of Diabarou respectively.
Resource definition and exploration drilling is continuing at Diabarou targeting two styles of gold mineralization:
- Bonanza grade gold associated with quartz veins; and
- Large gold systems associated with alteration zones.
AC drilling over the southern extent of the anomaly is ongoing, exploring for additional zones of bedrock gold mineralization.
At Disse, artisanal workings extend for over 880m with a coincident gold-in-soil anomaly and dump samples of up to 16.25g/t gold. Previous RC drilling by Oklo along a single traverse (3 holes) returned significant results including 16m at 2.30g/t gold.
A program of 23 AC holes completed during 2015 tested for strike extensions to the gold intersections below the artisanal workings on approximately 100m spaced traverses. Significant intersections included 21m at 5.67g/t Au and 3m at 12.80g/t Au. Drilling also intersected a second parallel structure located approximately 500m to the north on a recently opened artisanal trend, with 3m at 4.38g/t gold returned from one hole.
Based on these encouraging results, the Company intends to undertake a further drilling at Disse.
The Selingouma prospect comprises a series of open ended gold-in-soil anomalies extending over 6km with peak values of up to 0.45g/t gold. Previous reconnaissance auger and limited RC drilling intersected wide zones of hydrothermal alteration associated with elevated gold and highly elevated arsenic.
An IP geophysical survey completed over the northern 600m extent of the Selingouma anomaly outlined an interpreted sinistral oriented structure with potential dilational zones associated with surface gold anomalism. Oklo completed 30 vertical AC holes over the geophysical anomaly during 2015 and intersected encouraging bedrock gold mineralization including 18m at 1.75g/t Au.
An extensive program of AC drilling to provide initial coverage over the southern portion of the anomaly is planned for 2016.