首页|~(40)Ar/~(39)Ar dating of basaltic dykes swarm in Western Cameroon: Evidence of Late Paleozoic and Mesozoic magmatism in the corridor of the Cameroon Line

~(40)Ar/~(39)Ar dating of basaltic dykes swarm in Western Cameroon: Evidence of Late Paleozoic and Mesozoic magmatism in the corridor of the Cameroon Line

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  • Elsevier
~(40)Ar/~(39)Ar ages of three basalt dykes that intrude the Precambrian basement in the southern continental part of the Cretaceous Cameroon Line are presented. Specimen were sampled at Dschang, Maham and Kendem (Cameroon). The ages obtained are 421.3 ± 3.5 Ma (Dschang), 404.22 ± 3.51 Ma (Maham), and 192.10 ± 7.45 Ma (Kendem). The Dschang and Maham samples yield a relatively undisturbed spectrum while the Kendem sample shows an excess of argon but with plateau ages in the frame of the Mesozoic. Plateau ages at Dschang, Maham and Kendem represent more than 80% of the total ~(39)Ar released and are interpreted as emplacement ages. ~(40)Ar/~(39)Ar dating results confirm Devonian and Jurassic K/Ar ages obtained from similar dykes of the same region. Geochemically, the basalt dykes are subalkaline in composition with 45-50 wt.% SiO_2. Incompatible trace elements and rare earth elements are lower than that of the Cameroon Line basalts. Overall geochemical characteristics of the basalt dykes much more closely resemble those of tholeiites of the Benue Through in Nigeria that are interpreted as related to the opening of the Atlantic Ocean. The combination of ~(40)Ar/~(39)Ar ages, major, trace and rare earth elements geochemistry data demonstrate a magmatic phase that is significantly older and different of that of the Cretaceous Cameroon Line and younger than the dominantly granitic Neoproterozoic to early Paleozoic magmatism in the region. These findings offer new clues for a better understanding of the tectonic history of the region, particularly the origin of the Cameroon Line and Africa-South America pre-drift reconstitutions.

CameroonBasalt dykesPaleozoicMesozoicCameroon LineWest Gondwana

Jean Pierre Tchouankoue、Nicole Armelle Simeni Wambo、Armand Kagou Dongmo、Xian-Hua Li

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Department of Earth Sciences, University of Yaounde I, P.O. Box 812, Yaounde, Cameroon,State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, 19 Beitucheng West Road, Beijing 100029, China

Department of Earth Sciences, University of Ngaoundere, P.O. Box 454, Ngaoundere, Cameroon

Department of Earth Sciences, University of Dschang, P.O. Box 67, Dschang, Cameroon

State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, 19 Beitucheng West Road, Beijing 100029, China

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2014

10.1016/j.jafrearsci.2014.01.006

Journal of African earth sciences

Journal of African earth sciences

AHCI
ISSN：0899-5362
年,卷(期)：2014.93(May)
  • 13
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