Early Proterozoic crustal evolution in the birimian of Ghana: constraints from geochronology and isotope geochemistry

Taylor, Paul N.; Moorbath, S.; Leube, Alfred; Hirdes, W.

doi:10.1016/0301-9268(92)90086-4

Cited by 222 publications

(174 citation statements)

References 14 publications

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“…This period is divided into two phases. Though there is regional variation, broadly the Eoeburnean (also known as Eburnean I or the Tangaean; 2266-2150 Ma) precedes the Eburnean (2216-1980 (Taylor et al, 1992;Dia et al, 1997;Loh et al, 1999;Allibone et al, 2002;Gueye et al, 2007;Tshibubudze et al, 2009;Hein, 2010;de Kock et al, 2011). The Eoeburnean consists of volcanism, granitoid emplacement and fold, thrust tectonics, and is interpreted by Tshibubudze et al, (2015) to be a single diachronous event across the Birimian.…”

Section: Geological Settingmentioning

confidence: 99%

Discriminating fluid source regions in orogenic gold deposits using B-isotopes

Lambert-Smith

Rocholl

Treloar

et al. 2016

Geochimica et Cosmochimica Acta

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The genesis of orogenic gold deposits is commonly linked to hydrothermal ore fluids derived from metamorphic devolatilisation reactions. However, there is considerable debate as to the ultimate source of these fluids and the metals they transport. Tourmaline is a common gangue mineral in orogenic gold deposits. It is stable over a very wide P-T range, demonstrates limited volume diffusion of major and trace elements and is the main host of B in most rock types. We have used texturally resolved B-isotope analysis

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Section: Geological Settingmentioning

confidence: 99%

Discriminating fluid source regions in orogenic gold deposits using B-isotopes

Lambert-Smith

Rocholl

Treloar

et al. 2016

Geochimica et Cosmochimica Acta

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“…Recent studies have shown that the two units were formed contemporaneously (e.g., Leube et al 1990). On the basis of Sm-Nd isochron and model ages, Taylor et al (1992) constrained the age of Birimian supracrustal rocks of western Ghana to between 2.0 and 2.3 Gyr. Feybesse et al (2006) placed somewhat tighter constraints on the age of these rocks, around 2.10 to 2.15 Gyr.…”

Section: Geological Settingmentioning

confidence: 99%

Petrography, geochemistry, and alteration of country rocks from the Bosumtwi impact structure, Ghana

Karikari

Ferrière

Koeberl

et al. 2007

Meteorit & Planetary Scien

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Abstract-Samples of the country rocks that likely constituted the target rocks at the 1.07 Myr old Bosumtwi impact structure in Ghana, West Africa, collected outside of the crater rim in the northern and southern parts of the structure, were studied for their petrographic characteristics and analyzed for their major-and trace-element compositions. The country rocks, mainly meta-graywacke, shale, and phyllite of the Early Proterozoic Birimian Supergroup and some granites of similar age, are characterized by two generations of alteration. A pre-impact hydrothermal alteration, often along shear zones, is characterized by new growth of secondary minerals, such as chlorite, sericite, sulfides, and quartz, or replacement of some primary minerals, such as plagioclase and biotite, by secondary sericite and chlorite. A late, argillic alteration, mostly associated with the suevites, is characterized by alteration of the melt/glass clasts in the groundmass of suevites to phyllosilicates. Suevite, which occurs in restricted locations to the north and to the south-southwest of the crater rim, contains melt fragments, diaplectic quartz glass, ballen quartz, and clasts derived from the full variety of target rocks. No planar deformation features (PDFs) in quartz were found in the country rock samples, and only a few quartz grains in the suevite samples show PDFs, and in rare cases two sets of PDFs. Based on a total alkali element-silica (TAS) plot, the Bosumtwi granites have tonalitic to quartz-dioritic compositions. The Nb versus Y and Ta versus Yb discrimination plots show that these granites are of volcanic-arc tectonic provenance. Provenance studies of the metasedimentary rocks at the Bosumtwi crater have also indicated that the metasediments are volcanic-arc related. Compared to the average siderophile element contents of the upper continental crust, both country rocks and impact breccias of the Bosumtwi structure show elevated siderophile element contents. This, however, does not indicate the presence of an extraterrestrial component in Bosumtwi suevite, because the Birimian country rocks also have elevated siderophile element contents, which is thought to result from regional hydrothermal alteration that is also related to widespread sulfide and gold mineralization.

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“…In the reconstruction proposed by Ledru et al (1994) the Guaianese belts probably align with central and eastern belts of the West African Craton (Figure 8), though the alignment is not straight. In the African belts, the medium-grade Dabakalian metamorphic complex and lower-grade volcano-sedimentary associations of a similar age are found (Boher et al, 1992;Taylor et al, 1992;Hirdes et al, 1996;Hirdes and Davis, 1998).…”

Section: Eburnean Greenstone-granite Belts In the West African Cratonmentioning

confidence: 75%

Paleoproterozoic greenstone-granite belts in Northern Brazil and the former Guyana Shield - West African Craton province

McReath

Faraco

2006

Geol. USP, Sér. cient.

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The mainly meta-volcano-sedimentary Vila Nova Group and associated granites constitute separate belts, which form part of a large paleoproterozoic (mainly rhyacian) province in the Guyana Shield of which northern Brazil forms a part, and the West African Craton. In Brazil the southwestern Serra do Ipitinga and Serra Tumucumaque-Serra do Navio belts have no obvious geometrical extensions in the Guyanas or Venezuela, and may represent deposits formed at penecontemporaneous passive continental margins and ocean floor spreading centres. To the Northeast the Serra Lombarda-Tartarugalzinho and Oiapoque belts are continuations of Guianese belts. In the former the igneous rocks have geochemical characteristics of suprasubduction environments. Belts in the Guyana Shield and West African Craton have many similar features. The megaprovince evolved in a number of stages, which may have started at about 2.3 Ga, and continued with diminished activity after 2.11 Ga. Both major juvenile additions and (possibly minor) reworking of earlier crust contributed to the growth of the province. The major transcurrent deformation, responsible for the present structure of the belts, probably occurred during the later stages of evolution of the province, but metamorphism and deformation are registered even in the oldest rocks.Palavras-chave: terrenos paleoproterozóicos de greenstones e granitos; Escudo das Guianas; Norte brasileiro; Craton Oeste-Africano. RESUMOO Grupo Vila Nova, predominantemente meta-vulcanossedimentar e os granitos associados constituem cinturões que formam parte de uma grande província paleoproterozóica (predominantemente riaciana) localizada no Escudo Guianense do qual o Norte brasileiro faz parte, e no Craton Oeste-Africano. No Brasil identificam-se ambientes tectônicos diferenciados para os diferentes cinturões. No sudoeste da província os cinturões da Serra de Ipitinga, e da Serra de Tumucumaque ao Serra do Navio não encontram extensões geometricamente claras nas Guianas e Venezuela, e talvez representem depósitos penecontemporâneos formados em margens continentais passivas e bacias oceânicas. Seguindo para nordeste, os cinturões da Serra Lombarda até Tartarugalzinho e Oiapoque são continuações de cinturões presentes nas Guianas. Naquele, as características geoquímicas, tanto das rochas máficas metavulcânicas como das félsicas plutônicas posteriores, apontam para origens em zonas de supra-subducção. Os cinturões guianenses e oeste-africanos apresentam muitas feições e características semelhantes. A evolução da megaprovíncia ocorreu por etapas, desde talvez 2,3 Ga com atividade em diminuição depois de 2,11 Ga. Adições crustais, tanto juvenis quanto por retrabalhamento de crosta antiga, contribuíram para o crescimento da megaprovíncia. É provável que a deformação maior de transcorrência, responsável pela estrutura atual dos cinturões, ocorresse em fase tardia da evolução, embora mesmo as unidades mais antigas sejam deformadas e metamorfizadas.

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Early Proterozoic crustal evolution in the birimian of Ghana: constraints from geochronology and isotope geochemistry

Cited by 222 publications

References 14 publications

Discriminating fluid source regions in orogenic gold deposits using B-isotopes

Discriminating fluid source regions in orogenic gold deposits using B-isotopes

Petrography, geochemistry, and alteration of country rocks from the Bosumtwi impact structure, Ghana

Paleoproterozoic greenstone-granite belts in Northern Brazil and the former Guyana Shield - West African Craton province

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