Isotopic geochemistry (O, Sr, Pb) of the Golda Zuelva and Mboutou anorogenic complexes, North Cameroun; mantle origin with evidence for crustal contamination

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doi: 10.1016/0012-821X(82)90042-5
Authors:Jacquemin, Hervé; Sheppard, Simon M. F.; Vidal, Philippe
Author Affiliations:Primary:
Univ. Nancy, Lab Petrol., Vandoeuvre, France
Univ. Rennes, France
Volume Title:Earth and Planetary Science Letters
Source:Earth and Planetary Science Letters, 61(1), p.97-111. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0012-821X
Publication Date:1982
Note:In English. 51 refs.; illus. incl. 41 anal., 4 tables, geol. sketch maps
Summary:The annular (6-8 km diameter) Golda Zuelva and Mboutou anorogenic complexes are composed of a suite of alkaline plutonic rocks ranging from olivine-gabbro to amphibole- and biotite-granite. For the latter there are two overlapping centres; in the former, the plutonic rocks are associated with a later hawaiite-to-rhyolite suite. A Rb/Sr whole-rock isochron gives an age of 66 + or - 3 m.y. for the Golda Zuelva granites with an initial 87Sr/86Sr ratio of 0.7020, demonstrating that plutonism and volcanism were contemporaneous and probably cogenetic. For Golda Zuelva and the N Mboutou centre the isotopic ratios (O, Sr and Pb) support a mantle origin for the initial magmas. Unlike Sr isotopes, the O-isotopic ratios of the granitic end-members of Golda Zuelva (approx 7.5) indicate crustal contamination. For the younger S Mboutou centre, the isotopic data indicate more extensive magma-crust interaction, with Pb-isotopic ratios more markely displaced from the oceanic volcanic field. The low-18O granites probably record a magmatic process with subsequent minor post-magmatic alteration effects. The major- and trace-element systematics between the N and S Mboutou centres are directly comparable. The evolution of the magmas was dominated by fractional crystallization and progressive crustal contamination processes. [P.Br.]
Subjects:Absolute age; Acidic composition; Alkalic composition; Alkaline earth metals; Cenozoic; Complexes; Crust; Dates; Fractional crystallization; Genesis; Geochemistry; Igneous rocks; Intrusions; Isotopes; Lead; Magmas; Mantle; Metals; O-18/O-16; Oxygen; Plutonic rocks; Pollution; Rb/Sr; Ring complexes; Sr-87/Sr-86; Stable isotopes; Strontium; Tertiary; Volcanic rocks; Volcanism; Africa; Cameroon; West Africa; Golda Zuelva; Mboutou; Ratios
Coordinates:N100000 N120000 E0150000 E0100000
Abstract Numbers:83M/3203
Record ID:1983014109
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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