| The Early Pan-African geological development | | | | Northeast Africa, it is broadly similar to that of |
| between about 1200-680 million years ago is | | | | surrounding regions (ie Yemen, Saudi Arabia etc) |
| documents by a large number of geological and | | | | where Neoproterozoic rocks (low- to high grade |
| isotopic studies on Precamrian metavolcanic and | | | | meta-sedimentary and meta-volcanic rocks) record a |
| plutonic rocks exposed in the Arabian-Nubian Shield | | | | succession of mild collision, which resulted from the |
| (ANS). The Arabian-Nubian Shield of NE Africa and | | | | successive accretion of island arcs (Reischman. and |
| Arabia is one of the major orogenic belts formed | | | | Kröner, 1994). The earlier generation of gold |
| during the Neoproterozoic assembly of Greater | | | | mineralization in those regions formed in an island arc |
| Godwana similar to modern type plate tectonic | | | | setting related to the waning stage of tectono |
| processes i.e. oceanic island arc/back accretion and | | | | volcano activity. Consequently, during Pan African |
| microplate (terrane) collision (Stern,1994). The area | | | | orogeny that induced regional deformation, |
| has been intruded by batholiths and the most | | | | metamorphism, magmatism, collision of micro plates |
| predominant rocks in the Red Sea Hills are intrusive | | | | and crustal thickening, gold has been remobilized and |
| rocks, which covers 50%of the surface outcrop. | | | | reconcentrated either in the zones of metamorphic |
| Most of the African continent has been tectonically | | | | permeabilities and in collapse breccias (Hussein, 1999). |
| stable from orogenic episodes since about 500 million | | | | Gold mineralization in the North East occurs in |
| years ago. The Neoproterozoic (Pan African) orogenic | | | | different forms corresponding to different geological |
| episode have led to differentiate the continent into | | | | environment and at least three types are present:a) |
| two major features: (i) cratons which have not | | | | Premetamorphic mineralization associated with |
| suffered major orogenic deformation and | | | | stratiform massive sulfide deposit, e.g Northeast |
| metamorphism and (ii) mobile belts made up of rocks | | | | Sudan.b) Gold mineralization related to the regional |
| which are stable since 550 millions ago (Vail, 1985). | | | | tectono-metamorphic episode. E.g. North East Sudan, |
| The Nubian Shield underlies several Northeastern | | | | West Saudi Arabia.c) Gold mineralization related to |
| Africa countries such as Sudan, Ethiopia, Eritrea, | | | | shear zones, e.g. South Ethiopia, West Saudi Arabia, |
| Somalia and Egypt. These different areas share a | | | | Eritrea, North East Sudan. |
| similar geological evolution (accretion of volcanic island | | | | According to my knowledge, systematic geological |
| arcs) with mineral deposits formed by similar | | | | mapping using satellite images/remote sensing, very |
| processes (epithermal, mesothermal, VMS gold | | | | detailed litho-stratigraphic classification and accurate |
| deposits) | | | | mineral exploration had not been conducted in some |
| In view of geological and geotectonic setting of the | | | | of these countries such as Eritrea and Somalia. |