The Divole East Project consists of 28km2 of tenements located on the Boromo-Poura Shear Zone. The Boromo Belt hosts several major gold deposits, including the historic Poura gold mine which produced 0.75Moz of gold at an average grade of ~15g/t Au. The Divole East Project was acquired due to its favourable geological setting on the Boromo-Poura Shear Zone and significant gold mineralisation identified in artisanal workings.
Detailed regolith mapping of the Divole East lease areas was used to guide initial geochemical exploration. Areas amenable to soil sampling were sampled over parts of the Divole East project and shallow auger drilling was completed in areas with transported cover to augment soil geochemistry information.
Soil samples were collected initially on 400m x 40m spacing over amenable areas, with infill to 200m x 40m spacing undertaken in the gold anomalous zones. The most significant gold anomalies were located along the western edge of the project, coincident with artisanal workings, and the eastern half of the Divole East fold structure (Figure 1).
Figure 1: Divole East simplified geology map and geochemical sampling results
In March 2017, 10 diamond drill holes (total of 1,962m) were completed on 160m spaced sections to test the significance of gold mineralisation associated with the Divole Main artisanal workings (Figure 2). Gold mineralisation (+1g/t Au) was intersected in eight of the drill holes, with mineralisation associated with a shear zone which may intersect the main north-south structure mined in the artisanal site at the southern end of the workings.
Better drill intersections include:
- DDH002 –9m at 4.3g/t Au from 48m in highly altered silicified rocks, including 1.0m @ 29.2g/t Au from 52m and 1.0m @ 8.3g/t Au from 56.9m;
- DDH003 – 7.5m @ 1.6g/t Au from 65m, including 8m @ 7.8g/t Au from 70.0m;
- DDH006 – 9m @ 2.1g/t Au from 102.2m and 10.6m @ 1.2g/t Au from 120.8m; and
- DDH010 – 10m @ 0.7g/t Au from 71m and 8m @ 1.7g/t Au from 125m.
Figure 2: Diamond drilling locations at Divole Main Prospect
Figure 3: Core from DDH-02, 48-58m depth averaging 4.3g/t Au
Figure 4: Divole East ground magnetic image (1VD) over simplified geology
On the southern limb of the Divole East fold structure, a distinctly laminated quartz vein at least 180m long and extending under concealment to the north and south has been mapped and examined from artisanal workings. This laminated vein style is commonly associated with very high-grade mineralisation, as evidenced at Roxgold Inc.’s (TSE: ROXG) Yaramoko deposit, 90km south-west of Divole, that hosts a laminated vein grading >16g/t Au.
A reverse circulation (RC) drilling programme has been completed with 24 holes drilled for 2,385m (average depth 99m). The drill holes were designed to test continuity of the previously identified high-grade Divole Main prospect and the newly identified Divole East fold structure (Figure 5). The drilling samples have been sent to Ouagadougou for assaying and Arrow expects to receive the results in early September 2019.
Figure 5: Divole East fold structure detailed geology, structure and artisanal workings
with 2017 diamond drilling and proposed RC drill collars
Targeting work by Arrow highlighted the regional Boromo-Poura Shear Zone interpreted along the western flank of the Boromo greenstone belt, and a distinct strike change from N-S to NNE evident in the Divole West area. Regional magnetic data suggested the presence of unmapped greenstone belt stratigraphy in this favourable structural setting.
Arrow completed initial field work in early 2017, with a surface and auger geochemical approach used to confirm the geological interpretation and identify geochemically “live” structures in the project area.
Initial soil sampling on 800m x 80m east-west lines was undertaken in December 2017 (Figure 6), with a coherent 3km long NNE-striking gold anomaly identified parallel to and just east of the interpreted position of the Poura Shear Zone. Subsequent infill sampling on 200m x 40m lines confirmed a strong coherent gold-in-soil anomaly with values up to 400ppb Au (0.4g/t Au). Between the two soil highs is a topographic low representing a palaeo-drainage area where soil sampling is unlikely to provide an effective test and aircore drilling is required to test areas of thicker transported cover.
Figure 6: Divole West Regional geology and structure with soil sampling result
Figure 7: Divole West geology and significant auger drilling results
Auger sample assays up to 6,140ppb Au (6.1g/t Au) in hole DIVWAUG0038 were received over the southern lobe of the soil anomaly. Assays from holes over the northern lobe of the soil anomaly returned values up to 4,398ppb Au (4.4g/t Au) associated with quartz veined saprolite in hole DIVWAUG005 and 3,579ppb Au (3.6g/t Au) in hole DIVWAUG142. The auger drilling results suggest an array of northerly trending mineralised structures off the main NE-NNE trending Poura Shear Zone.
A 2,500m RC drilling programme is planned for 4Q 2019 at Divole West to test the high-grade auger results along the 2km anomalous zone on structures east of the Boromo-Poura Shear Zone.