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Cameroon Line alkaline magmatism (Central Africa); a reappraisal

Emmanuel Njonfang, Alexandre Nono, Pierre Kamgang, Vincent Ngako and Felix M. Tchoua
Cameroon Line alkaline magmatism (Central Africa); a reappraisal (in Volcanism and evolution of the African lithosphere, Luigi Beccaluva (editor), Gianluca Bianchini (editor) and Marjorie Wilson (editor))
Special Paper - Geological Society of America (June 2011) 478: 173-191

Abstract

Alkaline magmatism along the Cameroon Line has been active for at least 67 m.y. and is currently defined by an almost SW-NE geological lineament (mean value: N30 degrees E). Available petrological, geochemical, and structural data obtained over the last 20 yr lead us to reappraise its mechanism of emplacement. Known as the second most important geological curiosity in Africa, after the East African Rift system, it displays a continental part and an oceanic part, a unique feature in Africa and even in the world. The continental part contains both plutonic and volcanic massifs, and the oceanic part consists only of volcanic massifs. Plutonic rocks as a whole define a complete series of gabbro-diorite-monzonite-syenite-granite type, whereas volcanic rocks display abundant basic (basalt-hawaiite) and felsic (trachyte-phonolite-rhyolite) lavas with very few intermediate ones (mugearite-benmoreite). The formerly entire alkaline nature of these rocks is here ruled out by the discovery of volcanoes with geochemically transitional affinities in some areas of the continental sector. On the other hand, new K-Ar and (super 40) Ar/ (super 39) Ar dates confirm the absence of any age migration associated with the SW-NE linear trend. This lack of steady time-space migration and the SW-NE trend have also been observed in the magmatic provinces of Nigeria and Benue Trough, which share similar geochemical features with the Cameroon Line, and along the NE-SW major igneous lineaments in South Africa. The mechanism of such episodic emplacement of alkaline magmatism can be better explained in terms of complex interactions between hotspots and lithospheric fractures during African plate motion.


ISSN: 0072-1077
EISSN: 2331-219X
Coden: GSAPAZ
Serial Title: Special Paper - Geological Society of America
Serial Volume: 478
Title: Cameroon Line alkaline magmatism (Central Africa); a reappraisal
Title: Volcanism and evolution of the African lithosphere
Author(s): Njonfang, EmmanuelNono, AlexandreKamgang, PierreNgako, VincentTchoua, Felix M.
Author(s): Beccaluva, Luigieditor
Author(s): Bianchini, Gianlucaeditor
Author(s): Wilson, Marjorieeditor
Affiliation: Universite de Yaounde I, Laboratoire de Geologie, Yaounde, Cameroon
Affiliation: Universita di Ferrara, Dipartimento di Scienze della Terra, Ferrara, Italy
Pages: 173-191
Published: 201106
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
ISBN: 978-0-8137-2478-2
References: 98
Accession Number: 2014-002972
Categories: Igneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table, geol. sketch maps
N04°00'00" - N11°00'00", E08°00'00" - E14°00'00"
Secondary Affiliation: University of Leeds, GBR, United KingdomUniversite de Dschang, CMR, CameroonMega Uranium Cameroon, CMR, Cameroon
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201404
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