Gold Deposits in North East Africa
The Early Pan-African geological development between about 1200-680 million years ago is documents by a large number of geological and isotopic studies on Precamrian metavolcanic and plutonic rocks exposed in the Arabian-Nubian Shield (ANS). The Arabian-Nubian Shield of NE Africa and Arabia is one of the major orogenic belts formed during the Neoproterozoic assembly of Greater Godwana similar to modern type plate tectonic processes i.e. oceanic island arc/back accretion and microplate (terrane) collision (Stern,1994). The area has been intruded by batholiths and the most predominant rocks in the Red Sea Hills are intrusive rocks, which covers 50%of the surface outcrop.
Most of the African continent has been tectonically stable from orogenic episodes since about 500 million years ago. The Neoproterozoic (Pan African) orogenic episode have led to differentiate the continent into two major features: (i) cratons which have not suffered major orogenic deformation and metamorphism and (ii) mobile belts made up of rocks which are stable since 550 millions ago (Vail, 1985).
The Nubian Shield underlies several Northeastern Africa countries such as Sudan, Ethiopia, Eritrea, Somalia and Egypt. These different areas share a similar geological evolution (accretion of volcanic island arcs) with mineral deposits formed by similar processes (epithermal, mesothermal, VMS gold deposits)
In view of geological and geotectonic setting of the Northeast Africa, it is broadly similar to that of surrounding regions (ie Yemen, Saudi Arabia etc) where Neoproterozoic rocks (low- to high grade meta-sedimentary and meta-volcanic rocks) record a succession of mild collision, which resulted from the successive accretion of island arcs (Reischman. and Kröner, 1994). The earlier generation of gold mineralization in those regions formed in an island arc setting related to the waning stage of tectono volcano activity. Consequently, during Pan African orogeny that induced regional deformation, metamorphism, magmatism, collision of micro plates and crustal thickening, gold has been remobilized and reconcentrated either in the zones of metamorphic permeabilities and in collapse breccias (Hussein, 1999).
Gold mineralization in the North East occurs in different forms corresponding to different geological environment and at least three types are present:
a) Premetamorphic mineralization associated with stratiform massive sulfide deposit, e.g Northeast Sudan.
b) Gold mineralization related to the regional tectono-metamorphic episode. E.g. North East Sudan, West Saudi Arabia.
c) Gold mineralization related to shear zones, e.g. South Ethiopia, West Saudi Arabia, Eritrea, North East Sudan.
According to my knowledge, systematic geological mapping using satellite images/remote sensing, very detailed litho-stratigraphic classification and accurate mineral exploration had not been conducted in some of these countries such as Eritrea and Somalia.
I strongly suggest to conduct a detailed geological and geochemical investigation to find out gold and sulfides metallic, especially over meta-sedimentary and meta-volcanic rocks as I have no doubt that many of the these countries have precious metals including gold, zinc, silver, etc