TITLE:
Petrology and Geodynamic Context of Metabasic Rocks of Nemba Complex in the West Congo Fold Belt (Republic of Congo)
AUTHORS:
Louis Marie Joachim Djama, Ulrich Verne Matiaba Bazika, Florent Boudzoumou, Kinga Mouzeo
KEYWORDS:
West Congo, Neoproterozoic, Tholeiite, Andesitic Basalts, Basalts, MORB, Continental Rocks
JOURNAL NAME:
International Journal of Geosciences,
Vol.9 No.1,
January
12,
2018
ABSTRACT: The West Congo belt contains Paleoproterozoic and Neoproterozoic Units
which are deformed during Panafrican event. The Neoproterozoic Unit contains
rift and post rift deposits. The rift formation is made of metabasite, volcanic
and volcano-sedimentary rocks. The metabasite constitutes the Nemba Complex
which is considered put into place in a continental or oceanic context.
Samples from Nemba Complex collected along the “Congo ocean railway realignment”
are analyzed. Major elements indicate a low potassic subalkaline affinity
of the samples. Classification diagrams based of major elements shows
that the rocks are a tholeiitic serie constituted of andesitic basalts, sub-alkaline
andesitic basalts and a sub-alkaline to alkaline basalts. Some samples with a
calc-alkaline signature indicate a crustal contamination. The traces elements
plots indicate that the rocks are the MORB. The spectrum of multi-elements is
characteristic of continental rocks with a lithospheric origin. This is an
agreement with many works on the Nemba Complex and the alkali plutons
and acid volcanic rocks associated which attribute there a rift context.