The Gomoa Mangoase concession covering an approximate area of 75 km2 is situated about 60km southwest of Accra and lies along the Winneba – Kibi gold belt of Ghana.
The geology of the concession comprises mainly northeast trending Birimian greenstones and Birimian volcanoclastic sediments, intruded by basic intrusive (epidiorite, hornblendite) as well as felsic intrusive (Dixcove and Cape Coast type granitroids). Few minor intrusive of quartz, pegmatites and aplite veins are also present.
Gold mineralization is mainly associated with quartz veins within shear zones in the Birimian rocks. The other form of mineralization observed is contact mineralization between different rock unit and between mineralization may also be present.
Exploration work to date on the concession includes: geological mapping, soil geochemistry, ground magnetic survey as well as acromagnetic data interpretation aimed at delineating grounds within the concession that showed economic potential for gold mineralization.
A total of 3043 soil samples including 119 duplicates and 23 standards have been collected by GP Minerals on the concession. As a follow up to a successful soil sampling programme, a total of 31 trenches totaling 2467m were excavated yielding 2751 samples including 284 QAQC's (Standards, Blanks and Duplicates).
Gold bearing veining, related to D4 and D2 structures, are preferentially developed at lithological contacts, where competence contrast exits. It is interpreted that the shear zones within the concession presents discontinuous lenses with a distribution en-chellon pattern.
Regional studies and prospect evaluation work along best known, prolific and least studied structural corridors and mineralized trends in some of the gold belts of Ghana including the Winnebe-Kibi belt, the Asankrangwa Belt and Ashanti Belt suggest that point source gold-in-soil anomalies, low-level soil anomalies (20-55ppb) and weak trench anomalies (low-tenor trench intersections) are most invariably surface depletion phenomenon.
Significant mineralized structures have been intersected at depth in drill holes in several localities along the Obuasi-Central Ashanti Gold regional structures, where surface depletion has been recorded. In several localities within the Winneba-Kibi Belt, low-level (20-200ppb Au) soil anomalies and weak trench anomalies (0.1 – 0.5g/t) have been observed to overlie mineralized structures with significant drill hole intercepts. The low-tenor trench anomalies resulting from near surface leaching of gold have been observed to improve with depth in most cases along the belt.
Six low to medium – level trench mineralized structures defined on the Ahwere anomalous zone of the Gomoa Mangoase concession have been drill tested. These medium-level trench mineralized structures include 300m by an average of 5m mineralized structure with grades including 0.66g/t over 7m and 0.61g/t over 7m.
In February 2013, Gomoa Mining retained the services of Geodita Resources Ltd. to supervise and manage a Reverse Circulation Drilling programme on the Gomoa Mangoase Concession.
As a follow up on the 31 trenches excavated on the Ahwere prospect, 10 Reverse Circulation (RC) holes totaling 1005m were drilled. The objective of the preliminary RC drilling program was to locate mineral
Zones to permit additional trenching and drilling to be carried out on the other delineated soil anomalous zone.
Significant mineralization within the Ahwere prospect has been observed to be associated with a north northeast trending, west-southwest dipping shear zone extending over 300m. this mineralization is hosted within Birimian metavolcanics and occurs within a zone of shearing.
Best intercepts returned from the RC drilling include the following:-
- 1.3 g1tover 13m from 87m in hole GARC 03
- O.9g1tover 24m from 78m in hole GARC 04
- 2.6gttovcr 3m from 31m in bole GARC 05
- O.74g1t over 27m from 29m in bole GARC 07 and
- 2.0gft over 60) from 64m in hole GARC 010
The central zone consisting of two bodies define by holes GARC08 – GARC05 and GARC03 displays a pinch and swell type of mineralization having gold grades of 1m @ 0.6g/t in hole GARC06, swelling to 27m @ 0.74g/t including 4m @ 2.1g/t in hole GARC07, pinching to 2m @ 1.6g/t in hole GARC06 and swelling again to 10m @ 1.1g/t including 3m @ 0.87g/t in hole GARC05 and finally pinches to 2m @ 1.1g/t in hole GARC03.
The south-western zone consist of five parallel bodies with gold grades of 2m @ 0.6g/t, 6m @ 1.1g/t, 6m @ 0.65g/t. 3m @ l.3g/t and 12m @ 1.34g/t all in hole GARC03 The Gomoa Mangoase property hosts types of gold bearing mineralization; the sulphide-carbonated-potassium style (-/-Cu) mineralization and a quartz-free gold style mineralization. Low- tenor trench mineralization as known to increase with depth has been confirmed in several of the holes drilled. Trench GT023 recording 1 m quartz vein at 0.35g/t returned a gold grade of 1.5g/t in drill hole GARC03. In order to understand the geology and structural relationship of the gold mineralization, Geodita recommends investigating the northern and southern extensions of holes GARC010 and GARC003) respectively as they ended in Mineralization. Core drilling should be carried out to help understand the structures associated with the gold mineralization. The other soil anomalisms should be trench and drill tested prior to the shedding off of part of the concession. It is to achieve the above recommendations that Geodita is submitting this terminal report on behalf of Gomoa Mining Enterprise and applying for a one year extension of the current prospecting license.