Petrogenesis of gold-hosting Neoproterozoic syenite from the Tulu Kapi area, western Ethiopia

Warkisa, Geleta; Asrat, Asfawossen; Omitogun, A A; Oljira, Temesgen

doi:10.1016/j.jafrearsci.2021.104145

Cited by 1 publication

(5 citation statements)

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“…According to (Blades et al, 2015) the Arabian Nubian Shield Neoproterozoic basement complex is composed of a variety of supra-crustal and plutonic intrusive rocks that developed in the Tonian volcanic arc setting. The pre-, syn-, and post-tectonic plutonic intrusive rocks of varying composition have intruded the Arabian Nubian Shield of Western Ethiopian Neoproterozoic basement rocks (Warkisa et al, 2021) (Warkisa et al 2021). In view of (Blades et al, 2015(Blades et al, , 2019Warkisa et al, 2021) the Western Ethiopian Shield is originated during the east and west Gondwana collision and evidence for a complete tectonic cycle, island-arc, and arc-accretion activities.…”

Section: Geological Setting Of Western Ethiopian Shieldmentioning

confidence: 99%

“…The pre-, syn-, and post-tectonic plutonic intrusive rocks of varying composition have intruded the Arabian Nubian Shield of Western Ethiopian Neoproterozoic basement rocks (Warkisa et al, 2021) (Warkisa et al 2021). In view of (Blades et al, 2015(Blades et al, , 2019Warkisa et al, 2021) the Western Ethiopian Shield is originated during the east and west Gondwana collision and evidence for a complete tectonic cycle, island-arc, and arc-accretion activities. As studied by (Ayalew, 1997;Ayalew et al, 1990;Ayalew and Peccerillo, 1998) the Western Ethiopian Shield consists of Baro, Birbir, and Geba Domains (Fig.…”

Section: Geological Setting Of Western Ethiopian Shieldmentioning

confidence: 99%

“…The presence of albite indicates dynamic environment thereby suggesting low-grade regional metamorphism. The metabasalt of the Megele area is characterized by mineral assemblage: Prh + Ab +Act + Opx + Aug + Qtz + Amp (Warkisa et al, 2021).…”

Section: Petrography and Metamorphismmentioning

confidence: 99%

“…According to (Tadesse et al, 2003) most economic metallic mineral deposits are known to be found in this Neoproterozoic basement complex, including precious metals like Au, Pt, PGE, Ni, Ta, base metals, industrial minerals, and gemstones (i.e., ruby, emerald, sapphire, garnet), and decorative dimension stones. Several studies suggested that the tectonic and thermal evolution of Ethiopia's Juvenile Neoproterozoic volcano-sedimentary terranes of low-grade metamorphic belts and associated granitoid intrusions is primarily responsible for these metallic and nonmetallic mineral resources (Tadesse et al, 2003;Warkisa et al, 2021). Even though the geology of Western Ethiopia is still not well understood, different studies have been conducted in the region from different perspectives.…”

Section: Introductionmentioning

confidence: 99%

“…Western Ethiopian Shield is classified into Arabian Nubian Shield which comprises of Neoproterozoic low-grade metamorphic rocks and Mozambique belt includes moderate-to-high-grade gneisses (Kazmin, 1971;Kazmin et al, 1978;Kebede et al, 1999). Furthermore, detailed studies have been conducted in specific parts of the area focusing on geotectonic evolutions (Ayalew and Johnson 2002), petrology, geochemistry, and tectonic settings (Kebede et al, 1999;Alemu and Abebe, 2007;Warkisa et al, 2021). The Asosa area in the Western Ethiopian Shield which is the focus of this study has been one of the targeted areas for placer gold mining by artisanal workers since the 1930s (Bullock and Morgan, 2018).…”

Section: Introductionmentioning

confidence: 99%

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Petrogenesis of the Neoproterozoic rocks of Megele area, Asosa, Western Ethiopia

Oljira

Okunlola²,

Olatunji³

et al. 2022

Earth sci. res. j.

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The Western Ethiopian Shield is underlain by volcano-sedimentary terranes, gneissic terranes, and ophiolitic rocks intruded by different granitoid bodies. The Megele area is part of Western Ethiopian Shield and consist of a low-grade volcano-sedimentary zone that has been intruded by mafic (dolerite dyke) and granitoid intrusions (granodiorite, diorite, granite gneiss). To establish the origin of the distinctive lithologies of the locality and evaluate its mineral potential, petrological, petrographical, and geochemical characterization of these rocks were carried out. Hence, the lithological, geochemical, and petrogenetic features of the Neoproterozoic granitoid intrusives and associated metavolcanic, were illustrated through a combination of field mapping, petrological, and geochemical analysis. The petrological result obtained from the thin section analysis of the granitoids and metabasalt from Megele area indicates that, these rocks has been metamorphosed from lower green-schist facies to lower amphibolite facies as denoted by mineral assemblages such as albite + muscovite + prehnite+ quartz and actinolite + hornblende + epidote + garnet. The major and trace element geochemical analysis of granodiorite, diorite, and granite gneiss revealed that the rocks in the studied area were mainly calc-alkaline and peraluminous in nature in the SiO2 versus Na2O+K2O and A/NK versus A/CNK, the details of the results on the major and rare elements are stated in the result section respectively. The granitoids are S-type granites revealed silica saturated rock formed at the volcanic arc subduction (VAG) to syn-collisional (syn-COLD) tectonic setting by fractionation of LREE-enriched, HREE-depleted basaltic magma with considerable crustal input. This basaltic magma seems to be generated from the LREE-enriched, HREE-depleted mantle. In conclusion, the metabasalt is sub-alkaline (tholeiitic), metaluminous bodies generated at mid-oceanic ridge tectonic setting by partially melting of HREE-depleted and LREE-enriched basaltic magma. The magma sources are associated with the reworked sediment-laden crustal slabs from the subduction zone and resulted in S-type granitoid.

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