The Gourma Project is located within the Fada N’Gourma Greenstone Belt, 250km east of Ouagadougou and only 80 km south-southwest of Niger’s largest gold deposit, the 50,000 ounce per annum Samira Hill gold mine (1.9 million ounce project). The Project consists of six contiguous permits (Diabatou, Tyara, Foutouri Boutouanou, Tyabo and Kankandi) that cover a total area of approximately 1,300 km² (Figure 9). The Tyabo and Kankandi permits were acquired by Boss in January 2015 and, at Gryphon’s election, became part of the joint venture agreement.
Figure 9: Gourma Project Location Map
Boss was the first modern explorer on the property and completed a detailed aeromagnetic survey and extensive, mostly broad spaced reconnaissance style geochemical work involving several methods including soil, auger and rock chip sampling between 2010 and 2013. Work by Gryphon to date includes a regolith terrain and aeromagnetic interpretation, detailed BLEG stream sampling and selective lateritic lag sampling in areas where drainage geochemistry is an unreliable geochemical prospecting method, as well as 8525 soil samples plus preliminary shallow auger drilling which has returned a peak result of 27.5 g/t Au in saprolite.
Multi-element drainage and laterite sample assays have been received from the four original joint venture permits and the newly acquired Tyabo and Kankandi Tenements. The BLEG stream and lag results confirm the Gourma shear zone (GSZ) to be associated with some highly anomalous gold-in-drainage results. The stream analysis results also identified areas with very low background commodity and pathfinder element concentrations which are therefore areas where no more work is necessary making the task of reducing tenure, when necessary, something which can be achieved with confidence.
Figure 10: Gourma Project Geology and Prospects Overview.
Observations and samples obtained during these field visits are assisting with geological understanding, including recognition and understanding of the mineralisation styles and associated pathfinder elements, as well as the potential controls to mineralisation. This work will continue and will complement the exploration being undertaken. The small efficient exploration team are rapidly working towards generating high quality drill targets across the large land package.
Gourma Shear Zone
With the addition of the Tyabo and Kankandi Permits, the Gourma Project now includes approximately 60km of a gold bearing crustal shear which has received very little modern exploration. Along the shear there are numerous artisanal workings. Geochemical sampling by Boss utilised both soil and auger geochemistry, identifying a number of prospects which received various levels of follow-up but no substantial drilling. The Bongori South prospect returned historic rock chips to 41.0g/t, 19.2 g/t and 12.0g/t gold. 12km to the east the Foutori Prospect returned peak rock chip results of 21.6 g/t, 11.4 g/t and 4.7 g/t gold.
BLEG stream sediment sampling was undertaken on the recently acquired Tyabo and Kankandi permits. The QA/QC data was verified and found to be extremely precise. The drainage results are encouraging with robust and strongly anomalous areas identified within the Kankandi permit at the Wourouwou and Djinta prospects on the Gourma Shear Zone.
Soil sampling was conducted over Djinta, Wourawou, Bongi, Fouanbori, Lotta, Sefatendo, Gariaga and Tambiga prospects. 3438 samples were submitted to the lab and a further 2080 read by pXRF seeking indications of potential pathfinder elements, lithological discriminators or alternative commodity elements returning peak results to 13.5 g/t Au from the Sefatendo-Tambouanou (S-T) Prospect.
Gariaga-Diabatou Trend – Multiple Targets
The Gariaga-Diabatou mineralised trend extends southwest onto the recently acquired Tyabo permit. There are numerous bedrock and eluvial gold workings along the trend, extending over a strike length exceeding 10km. Mineralisation on the trend is interpreted to be on the eastern flank of an antiform which represents a bounding shear zone. Quartz tourmaline veins are more common close to the interpreted contact.
First pass drilling by Boss in 2012 returned best aircore results of 3m @ 11.3g/t gold and 14m @ 2.1g/t gold from Gariaga, and 14m @ 2.1g/t gold and 12m @ 2.8 g/t gold from the Diabatou Prospects. The aircore drilling at Diabatou remained in saprolite to an end of hole depth of 80m.
Gariaga is hosted in mafic schist and extends to the southwest beyond a contact with metasediments. Common to both prospects is mineralisation associated with quartz tourmaline veins. The metasediments comprise foliated volcanic sandstone and phyllite, carbonaceous shale and deeply weathered feldspathic semi-schist with lesser amounts of feldspar porphyroblastic schist. There is a quartz rich sandstone (quartz arenite) containing conglomeratic bands in the south west portion of the trend. Mineralisation in all three trends consists of grey, glassy to smokey quartz veins and disseminated mineralisation associated with shearing and silicified zones. This style of mineralisation represents a highly prospective target for hosting broad zones of mineralisation. The disseminated and silicified zones are strongly associated with sericite and pyrite alteration with some malachite and chalcopyrite observed along the trend.
Phased soil sampling has continued at the S-T prospect on the eastern Boutouanou permit and the Gariaga prospect on the Diabatou permit, returning a peak soil of 13.5 g/t Au. The S-T prospect occurs within a northwest trending corridor of intrusive units where rock chipping from artisanal workings has returned historical results up to 42g/t gold. A modest soil anomaly is being outlined extending for around 4km which will allow auger testing once areas across the Gourma project are able to be objectively prioritised.
At Gariaga prospect, soil sampling has continued with a single spur line to the east, following up on anomalous lag samples collected by Gryphon in 2014, returning 1.59g/t Au.
Figure 3: Gariaga – Diabatou Trend.
Foutouri, Lotto, Tambouana, Boutounou – Eastern Target Areas
A number of prospects with high grade surface mineralisation had previously been identified by Boss in the east and southeast of the project. In the far southeast of the tenement package the Sefatendano and Tambouana Prospects are present in northwest striking structures within sheared and altered granite and in gabbro respectively. The high grade veins in the gabbro were sampled by Boss returning peak results of 42.4 g/t, 35.6 g/t and 12.2g/t gold. The prospects are associated with strong gold-in-drainage responses. A soil geochemical program has been completed covering the strike extent and probable source of the multiple drainage anomalies; results pending.
Also of significance are the Lotto-Tampora Prospects where Boss returned best rock chips of 55.3 g/t, 19.7 g/t and 14.2 g/t gold from laminated quartz veins. Sampling by Gryphon at Lotto has returned a best rock chip result of 19.7 g/t gold. The soils responses to date have been weak, but the drainage geochemistry supports a decision to undertake further work in the area.