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Book Chapter

Proterozoic evolution of the Nigeria–Boborema province

By
S. S. Dada
S. S. Dada
Department of Earth Sciences
,
Ajayi Crowther University
,
Oyo, Oyo State
,
Nigeria
(e-mail: ssdada47@yahoo.com)
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Published:
January 01, 2008

Abstract

Structural, geochronological, geochemical and mineralization patterns in the Nigeria–Borborema province of western Africa and NE Brazil reflect a complex Proterozoic evolution culminating in the Neoproterozoic Pan-African/Brasiliano orogenesis (c. 600 Ma). Reworking of the Archaean–early Proterozoic crust produced heterogeneous deformation exemplified by prevalent shears, migmatization, granitization and intrusion of large volumes of granitoids typical of a Himalayan-type thickened crust resulting from continent–continent collision. Dominant north–south to east–west structures, with prominent penetrative fabric and mylonitised wrench faults, refolded, transpressed, or even obliterated older structural trends, which are preserved in nappes of the central Sahara region (NW Africa to Nigeria) and in NE Brazil. Anatexis and recrystallisation were coeval with emplacement of Pan-African granitoids throughout this mobile belt. Bulk chemical modification, especially affecting magmatophile elements and REE patterns, attest to chemical exchange between Archaean basement and Pan-African/Brasiliano rocks. Older crust is present in both regions, including early (3.6–3.5 Ga), mid (3.1 Ga) and late (2.7–2.5 Ga) Archaean, as well as large areas of Palaeoproterozoic rocks reworked by the c. 600 Ma tectono-thermal events. The extent and interpretation of Eburnian/Transamazonian (2.1–2.0 Ga) events have not yet been resolved due to inadequate structural and isotopic data. Litho-structural control of Au, Sn, Nb and Ta mineralization relates to main or late-stage Pan-African deformation.

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Geological Society, London, Special Publications

West Gondwana: Pre-Cenozoic Correlations Across the South Atlantic Region

R. J. Pankhurst
R. J. Pankhurst
British Geological Survey, UK
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R. A. J. Trouw
R. A. J. Trouw
Universidade Federale do Rio de Janeiro
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B. B. de Brito Neves
B. B. de Brito Neves
Universidade de São Paulo, Brazil
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M. J. de Wit
M. J. de Wit
University of Cape Town, South Africa
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Geological Society of London
Volume
294
ISBN electronic:
9781862395428
Publication date:
January 01, 2008

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