TITLE:
The Geodynamic Context of the Cenozoic Volcanism of the Cap-Vert Peninsula (Senegal)
AUTHORS:
Abdoulaye Ndiaye, Papa Malick Ngom
KEYWORDS:
Cenozoic, Alkaline Volcanism, Oceanic Islands Basalts, Cap-Vert Peninsula, Senegalo-Mauritania Basin
JOURNAL NAME:
International Journal of Geosciences,
Vol.5 No.12,
November
27,
2014
ABSTRACT: The
Cenozoic alkaline volcanism of the Senegalo-Mauritania sedimentary basin
presents an episodic long-lasting volcanic activity from the Eocene-Oligocene
boundary up to the Quaternary. Two volcanic episodes are usually distinguished
on stratigraphical grounds: a Miocene one and a Quaternary one separated by a
period of quiescence of several million years corresponding to the main phase
of lateritic weathering. The Tertiary lavas are highly silica-undersaturated
alkaline rocks ranging from nephelinites to basanites. They contain nepheline
and fassaite-type clinopyroxene in their mineralogy. The Quaternary lavas are
more evolved with Hy-normative in comparison to the Tertiary ones; they are
composed of basanites and medium to coarser-grained dolerites. The distribution
of the REE and other incompatible elements are typical of alkaline lavas with
generally strong LREE enrichment without significant Eu anomaly. The Cenozoic
Cap-Vert lavas have OIB (oceanic islands basalts)-affinities as shown by their
relatively radiogenic Nd and unradiogenic Sr characters closed to the HIMU-OIB.
This suggests a HIMU-type end member in the magma sources which is fairly
comparable to those erupted in the Canaries and Cape Verde archipelagoes during
the same period.