The Pan-African Trans-Saharan Belt in the Hoggar Shield (Algeria, Mali, Niger): A Review

Boullier, Anne-Marie

doi:10.1007/978-3-642-84153-8_5

Cited by 19 publications

(13 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The Hoggar-Iforas belt, which has been studied for more than 40 years, is a reference area to describe the Pan-African geodynamic evolution in West Africa (Boullier, 1991). Available detailed mapping, together with reliable geochronological data (Black et al, 1979;Caby, 1970Caby, , 1987 were used to produce a model for Pan-African orogenic behavior in this part of Africa.…”

Section: The Hoggar-iforas Beltmentioning

confidence: 99%

Pan-African tectonic evolution and glacial events registered in Neoproterozoic to Cambrian cratonic and foreland basins of West Africa

Deynoux

Affaton

Trompette³

et al. 2006

Journal of African Earth Sciences

144

View full text Add to dashboard Cite

Section: The Hoggar-iforas Beltmentioning

confidence: 99%

Pan-African tectonic evolution and glacial events registered in Neoproterozoic to Cambrian cratonic and foreland basins of West Africa

Deynoux

Affaton

Trompette³

et al. 2006

Journal of African Earth Sciences

144

View full text Add to dashboard Cite

“…The ocean closed at $600 Ma, when subduction of oceanic lithosphere formed the TransSaharan orogenic belt (Boullier, 1991;Caby and Monie, 2003), which includes the Iforas orogen (Dostal et al, 1994) and the Dahomeyides (Attoh et al, 1997).…”

Section: Regional Geology Of North Africamentioning

confidence: 99%

“…The largest part of the Tuareg shield is the Hoggar massif, which contains a complex sequence of fault slices apparently assembled by right-lateral transpression during Late Neoproterozoic time (Caby et al, 1989;Boullier, 1991;Black et al, 1994). Crystalline parts of the massif range from Archean through the Mesoproterozoic and include mainly ortho-and paragneisses, with some blocks metamorphosed to granulite facies (Caby, 1996).…”

Section: Regional Geology Of North Africamentioning

confidence: 99%

Tectonic significance of Late Neoproterozoic granites from the Tibesti massif in southern Libya inferred from Sr and Nd isotopes and U–Pb zircon data

Suayah

Miller

et al. 2006

Journal of African Earth Sciences

View full text Add to dashboard Cite

“…The Amesmessa district lies in a major lithospheric structure (Boullier 1991) which behaved as a ductile strike-slip fault, under upper greenschist facies metamorphic conditions (biotite subfacies), during late Pan African tectonics. The shear zone acted as a pathway for magmas which originated either from crustal (felsic magmas), upper mantle (marie magmas) or deepseated (carbonatite) sources; the felsic dike complex includes gabbro-pyroxenite bodies and rare carbonatite lenses.…”

Section: Tectonic Evolution Of the Shear Zonementioning

confidence: 99%

Gold mineralization in the West Hoggar shear zone, Algeria

Ferkous

Leblanc

1995

Mineral. Deposita

View full text Add to dashboard Cite

Abstract. The Amesmessa gold prospect is located along a vertical N-S-trending crustal-scale ductile shear zone; stretching lineations are subhorizontal. This major shear zone is a Late Pan African dextral strike-slip fault of the Pharusian Belt of the Tuareg Shield (Algeria). The Amesmessa shear zone is asymmetric: strong thermal and deformational gradients are present along its western border where biotitic ultramylonites are in contact with a rigid Archean complex (In Ouzzal block), whereas there is a progressive gradation, through mylonite then protomylonite, to the Proterozoic gneiss of the Eastern block which displays co-axial Pan African structures. The Amesmessa shear zone is characterized by the presence of a felsic dike complex emplaced during shearing, and forming the most important parent material for ultramylonites. Basic magmas and carbonatites also intruded within the shear zone. The gold-rich quartz veins are located within the ultramylonitic western part of the shear zone. These N-S-trending laminated quartz veins formed during the late increments of shearing (plastic/brittle transition), by repeated syntectonic hydraulic fracturing atong zones of rheological contrast parallel to foliation. The ore mineral association (pyrite, galena, native gold, sphalerite) crystallized in the deformed quartz matrix along late shear planes. Undeformed E-W trending banded quartz veins are present in the mylonitic eastern part of the shear zone; their gold content is low and no native gold has been observed. A strong hydrothermal alteration resulted in the development (along the walls of the N-S gold-bearing quartz veins) of a 5-m-wide carbonate-sericite-albite-pyrite secondary mineral association which implies an important CO2 supply and moderate temperature conditions. There is no alteration halo around the E-W quartz veins. Ultramylonites, hydrothermally altered rocks and quartz veins display similar REE patterns characterized by strong LREE enrichments. Shear-related fluids could be likely parental fluids for the Amesmessa gold mineralization and the associated hydrothermal alteration. Hydrothermal fluids were drawn into dilation zones and filled opening fractures along the main planar discontinuity of the most deformed rocks. The supply of CO2 may come from a deep-seated source as suggested by the presence of carbonatite dikes in the shear zones and the existence of CO2-H20-rich fluid inclusions in quartz. The location of the gold-bearing quartz veins in the western part of the shear zone can be explained by the presence of strong thermal and rheological gradients.Shear zone-hosted vein-type gold deposits are economically important in Archean shields and occur for example in Canada Colvine et al. 1988), Australia (Groves and Phillips 1987) and Southern Africa (Foster and Wilson 1984;Viljoen 1984). These vein-type gold deposits include mainly native gold associated with pyrite and/or arsenopyrite in a quartz gangue; their wall-rocks, which are generally derived from ultramafic-mafic greenstone-belt material, ...

show abstract

The Pan-African Trans-Saharan Belt in the Hoggar Shield (Algeria, Mali, Niger): A Review

Cited by 19 publications

References 44 publications

Pan-African tectonic evolution and glacial events registered in Neoproterozoic to Cambrian cratonic and foreland basins of West Africa

Pan-African tectonic evolution and glacial events registered in Neoproterozoic to Cambrian cratonic and foreland basins of West Africa

Tectonic significance of Late Neoproterozoic granites from the Tibesti massif in southern Libya inferred from Sr and Nd isotopes and U–Pb zircon data

Gold mineralization in the West Hoggar shear zone, Algeria

Contact Info

Product

Resources

About