Kofot - Gerger
The Kofot – Gerger area is ~10 to the NE and E of Himbol village, in the northern half of the license area. It is located about 75km NE, along the regional trend of the Bisha VMS deposit and approximately 60km south of Chalice Gold Mines’ Koka Gold deposit.
The Kofot - Gerger area has seen the most exploration by London Africa during the first year of activity, due to early detection of significant gold and copper. High copper values in particular were initially considered to reflect a potential VMS system; however further work indicates that skarn mineralization is equally likely as a genetic model for the mineralization. The company conducted a 200 m x 200 m grid soil survey of 425 samples, and a gravity survey in the same area. The results of these surveys are given below along with prospecting assay results.
Geology
In the Kofot – Gerger area, volcanic and sedimentary rocks extend 6-12 km wide E-W between the Debir Sala granitic terrain to the east, and granitic terrain to the west. Within the volcanic and sedimentary strata, gabbro complexes, late- to post-tectonic granitic intrusions and associated dikes constitute a significant volume of the bedrock. The volcanic rocks include, from west to east: a mafic volcanic package west of the main prospective trend; an intermediate volcanic zone includes siliciclastic fragmental tuffs, ash tuffs, pyritic dacite flows, and intercalated marble, cherts, carbonaceous shale units up to 50m thick, and a late- to post-tectonic granodiorite intrusion to the east. The general strike of the rock fabric is 20°NE dipping to the East at an angle of 80°.
Magnetite/hematite siliceous iron formation units up to 5 m-thick are present in the Kofot area to the north, whereas Cu- and Au-bearing garnetite units up to 2 m thick are present in the Gerger area to the south, as well as lean iron formation units up to 5 m-thick. Gossans are developed over both garnetite and iron formation, and have malachite at surface in numerous areas. The mafic strata in the vicinity of the garnetite and the iron formations in both the Kofot and Gerger areas and areas in between have moderate chlorite alteration.
In the Gerger area, a late- to post-tectonic granodiroite intrusion is present immediately east of the Cu Au- enriched garnetite and gossan occurrences.
Mineralization
At Kofot, multiple Fe rich gossans and magnetic exhalite horizons were encountered along on a chlorite altered felsic volcanic rocks intercalated with calcareous-sediment package. Significant chlorite alteration can be noted on the West of the main zone. The main zone has intense epidote alteration. East of the main zone is characterized by wide zone of intense sericitization and FeOx alteration with stringer type as well as fracture controlled mineralization.
At Gerger, thin Fe rich gossans, magnetite and garnetite are the characteristic units in the Gerger horizon. Notable malachite rich gossan as well as Garnetite packages ware encountered about 2km south of Kofot. The Gerger Prospect is about 5-10m mineralized zone which was traced for about 3km. The system is intruded by younger grano-diorite unit to the south. Chlorite alteration can be noted on the West of the main zone. The main zone has intense silica alteration and malachite rich stringer- like systems. East of the main zone is intruded with a semi conformable 500m x 3km granodiorite unit. It cuts the main zone to the south.
The geology of the area under consideration is made up of volcaniclastic rocks, meta- sedimentary rocks, syn-tectonic granite and post-tectonic intrusion package. The western part of the target area is occupied by mafic ash tuff. This unit is bounded by 50m thick thinly foliated light yellowish-brown slate unit, to the east. The central part of the area which is characterized by ridge topography and gossan as well as garnetite outcrop is dominated by the chlorite altered ash tuff and less commonly basalt unit. This unit has incorporated a package of meta-sedimentary units (marble, marl, chert and graphitic shale), pyritic dacite flow and epidote altered syn-tectonic granite. At the Kofot locality multiple of hematite-gossan and magnetic exhalite outcrops were encountered. The general strike of the rock fabric is 20°NE dipping to the East at an angle of 80°. The eastern flank of the garnetite formation is bounded by post-tectonic intrusion. Intense silicification and malac hite enrichment was noted in this stratiform layer. The garnetite formation has an outcrop length of about 1.4km and south of it, NNE trending isolated lenses of hematite-gossan outcrop occupies for about 1.2km strike length. This sequence is cut by the younger intrusion along the southern part. The strata are also cut by thin ,70°NW trending quartz veins. East of the stratabound mineralization, at the Gerger area, the geology is dominated by intercalation of chlorite altered intermediate composition volcaniclastic rock and highly deformed hematite-sericite altered syn-tectonic granite with significant stringer mineralization. In addition, 500m east of the garnet bearing stratiform layer, a succession of NNE trending slate, lapilli-tuff, lithic-tuff and mafic tuff horizons stretching from West to East were observed, in about a 120m wide area.
Results
At Kofot, Cu-Au malachite-bearing gossans are in an 800m x 100m area, that is a folded volcanic- exhalite/iron formation sequence. Surface samples taken from the zone have up to 2.26 g/t Au and 3% Cu. The system has coincident Au and Cu anomaly on the surface. At Gerger, malachite rich gossan+ garnetite samples from the surface have up to 4.58g/t Au and 4.5 wt.% Cu. Most of the surface samples have 0.2-0.5 g/t Au.
Gallery
