On the tectonics and metallogenesis of West Africa: a model incorporating new geophysical data

Geoexploration
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Abstract

The gold, diamond and manganese deposits of Ghana have attracted commercial interest, but appropriate geophysical data to delineate the tectonic setting of these and other deposits have been lacking until recently. Recent gravity surveys, however, now cover about 75% of the country. When used in a synthesis of the sometimes contradictory existing theories about the geology and metallogenesis of West Africa, the available gravity, magnetic, and seismic data lead to a preliminary tectonic model that postulates rifting at the time of the (1800-2000 m.y. old) Eburnean orogeny and is consistent with the occurrences of mineral deposits in the region. In this model, diamond-bearing kimberlites formed during the commencement of rifting during the Eburnean orogenesis. Later emplacement of kimberlites was associated with the initiation of Mesozoic rifting of Gondwanaland. Primary gold vein deposits were probably formed by the migration of hydrothermal fluids (associated with the formation of granitoids) into dilatant zones, such as rift-related faults and anticlinal axial areas, toward the end of the Eburnean orogeny. At this time, the major concordant granitoids were formed, with smaller plutonic granitoids forming on the fringes of the concordant masses as partial melting fractions of the latter. Sedimentary manganese deposits were formed along the margins of rift lakes toward the end of the orogeny.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title On the tectonics and metallogenesis of West Africa: a model incorporating new geophysical data
Series title Geoexploration
DOI 10.1016/0016-7142(82)90027-8
Volume 20
Issue 3-4
Year Published 1982
Language English
Publisher Elsevier
Contributing office(s) Earth Resources Observation and Science (EROS) Center
Description 33 p.
First page 295
Last page 327
Other Geospatial Africa
Online Only (Y/N) N
Additional Online Files (Y/N) N