Geological setting and tectonic subdivision of the Neoproterozoic orogenic belt of Tuludimtu, western Ethiopia

Allen, Alistair; Tadesse, Gebremedhin

doi:10.1016/s0899-5362(03)00045-9

Cited by 32 publications

(54 citation statements)

References 34 publications

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“…The study area is found within the Sirkole and Daka domains [22,23]. These consist of alternating gneiss and volcano-sedimentary sequences, interpreted as an imbricated basement-cover thrust-nappe complex.…”

Section: Structural Controls On Metamorphismmentioning

confidence: 99%

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A New Occurrence of (Gold-Bearing) Graphite in the Assosa Region, Benishangul-Gumuz State, W Ethiopia

Bullock¹,

Morgan²

2015

JEASE

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Abstract:The Assosa region of western Ethiopia hosts newly discovered and potentially highly economic graphite-bearing schist units. Due to its unique physical and chemical properties, graphite is quickly becoming an increasingly important economic resource. Graphite occurs over much of the area, and is hosted predominantly by quartz-graphitic schist, quartz-feldspar-mica schist and quartzite. The quartz-graphitic schist covers an area of 37 km 2 , forming steep valleys and ridges across a 190 km long belt.Graphite is texturally-variable within and across units. Crystal habit varies from highly crystalline to irregular flakes. Flake sizes range from amorphous and crystalline small flake to coarse large flake (> 150 µm), with beneficiation of ~ 70% and yield potential of > 95% (froth flotation methods). The license area is already a well-known gold-hosting area, and potentially economic gold deposits occur within the graphite-bearing units. Overall, the site shows excellent geochemical indicators, field observations and historical accounts of high gold content. It is suggested that textural variations may be the product of (1) early in-situ formation during (early-to late-Proterozoic) prograde metamorphism and (2) later vein-type mineralization during retrograde metamorphism. The discovery of graphite in western Ethiopia is the first documented and preliminary studies suggest a high economic potential for the deposits.

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Section: Structural Controls On Metamorphismmentioning

confidence: 99%

“…The contact between the Meta-granitoids and meta-volcanic is tectonic (NE-SW striking Kuluk Shear Zone; Fig. 2) [22,23].…”

Section: Structural Controls On Metamorphismmentioning

confidence: 99%

A New Occurrence of (Gold-Bearing) Graphite in the Assosa Region, Benishangul-Gumuz State, W Ethiopia

Bullock¹,

Morgan²

2015

JEASE

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“…Ayalew and Peccerillo (1998) and Kebede et al (1999) inferred that "late to postkinematic" plutons possessed geochemical signatures of both subduction related and intraplate components. Allen and Tadesse (2003) classified and described the N S trending Tuludimtu Belt, where the area of study of this work lies, into five lithotectonic domains. They interpreted the belts as being a collision of the orogenic belt formed during the assembly of west Gondwana before the final closure of the Mozambique Ocean.…”

Section: Regional Geologymentioning

confidence: 99%

“…A part of the MB is indicated (modified after Abdelsalam and Stern, 1996;Worku and Schandelmeier, 1996). (b) A geological map of part of the Tulu Dimtu orogenic belt in the Ghimbi region (modified after Allen and Tadesse, 2003). Three of the five litho tectonic domains are indicated.…”

Section: Regional Geologymentioning

confidence: 99%

“…The Bikilal Ghimbi gabbro is elliptical in shape, and has a concentric structure, with olivine gabbro in its center and hornblende gabbro and hornblendite at its periphery. The Bikilal Ghimbi gabbro is regarded as a syn to post tectonic intrusion, based on its relationship with the surrounding country rocks (Abraham, 1989;Alemu and Abebe, 2000;Beshawered, 2001;Allen and Tadesse, 2003). Previous studies have regarded the gabbro as being two separate bodies, namely a syn tectonic hornblende gabbro and a post tectonic olivine gabbro.…”

Section: Introductionmentioning

confidence: 99%

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Petrogenesis of the Neoproterozoic Bikilal-Ghimbi gabbro, Western Ethiopia

Woldemichael

Kimura²

2008

Journal of Mineralogical and Petrological Sciences

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The Western Ethiopian Shield is an exposed Neoproterozoic metamorphic belt and forms part of the Arabian Nubian Shield. The metamorphic belt consists of high grade biotite gneisses, low grade volcanogenic sediments, and mafic ultramafic complexes. The Bikilal Ghimbi gabbro is a mafic body surrounded by these gneissic rocks, and is located 440 km west of Addis Ababa. The gabbro is elliptical in shape and covers an area of 350 km 2 . It consists of olivine gabbro in its center and hornblende gabbro and hornblendite at the perimeter. The olivine gabbros are very fresh and undeformed, but hornblende bearing suites have deformational textures. Each rock type can be divided into apatite bearing and apatite free subtypes. The major element geochemistry shows that despite the differences between the olivine and the hornblende gabbros, there is no systematic chemical contrast between the lithotypes except for the fluid mobile elements, suggesting an origin from a common parental magma. Only the perimeter is affected by metasomatism. An estimation of the parental magma composition using the trace element abundance in fresh clinopyroxenes and fresh olivine gabbro bulk rock suggests an intraplate type tholeiite. Crystallization model calculations using a tholeiitic parental magma suggest that the gabbros crystallized in a manner where small amounts of interstitial melt were retained. The apatite bearing varieties are always associated with Mg rich mineral phases, suggesting an origin from the supercooling of replenished basalt into an evolved low temperature magma chamber. The supercooling caused saturation of the apatite in the basalt melt, along with Mg rich crystals, and these later mixed together with the more evolved crystals that had precipitated previously. The intraplate type tholeiitic parental magma suggests plume type magmatism for the origin of the Bikilal Ghimbi gabbro body.

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The Grand Ethiopian Renaissance Dam and the Ethiopian Challenge of Hydropolitical Hegemony on the Nile Basin

Tayie

2018

The Handbook of Environmental Chemistry

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Geological setting and tectonic subdivision of the Neoproterozoic orogenic belt of Tuludimtu, western Ethiopia

Cited by 32 publications

References 34 publications

A New Occurrence of (Gold-Bearing) Graphite in the Assosa Region, Benishangul-Gumuz State, W Ethiopia

A New Occurrence of (Gold-Bearing) Graphite in the Assosa Region, Benishangul-Gumuz State, W Ethiopia

Petrogenesis of the Neoproterozoic Bikilal-Ghimbi gabbro, Western Ethiopia

The Grand Ethiopian Renaissance Dam and the Ethiopian Challenge of Hydropolitical Hegemony on the Nile Basin

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