TITLE:
Geoelectric Structure of the Crust along the Mbere Trough (South Adamawa) from Audio-Magnetotelluric Data
AUTHORS:
Ludovic Houetchak Kande, Joseph Kamguia, Jean Marie Tadjou, Robert Nouayou
KEYWORDS:
Adamawa; Trough; Fault; Resistivity; Pseudo-Section; Geoelectric Section
JOURNAL NAME:
International Journal of Geosciences,
Vol.4 No.8,
October
28,
2013
ABSTRACT: The South Adamawa trough represents a major structure
associated to the tectonic activity in the Adamawa region. The Mbere and the
Djerem troughs represent the eastern and the western parts of the South Adamawa trough respectively. The
audio-magnetotelluric (AMT) method is used to study the Mbere trough and to bring
out tectonic features that affect the basement of this region during the
Cretaceous. From analysis and interpretation of AMT data, based on pseudo-section
and geoelectric section, two geologic models are constructed across the trough
at Belel and Nyambaka. Those models bring more information on the sediments
thickness and the borders faults of the trough compared to previous
studies. The results shows that the Mbere trough is dissymmetric, and bounded
on its northern side by an intra-gneissic fault and on its southern side by two
faults with at least one considered as a faulted contact between the granitic
and gneissic rocks. The sediments filling of the trough are consist mainly of
conglomerates on which lay sandstones. The thickness of these sediments is
about 2060 m at Belel and decreases to about 1800
m at Nyambaka, with a low sandstones thickness, which does
not exceed 360 m.
The basement consists of granite in the South of the trough and gneiss in the North, with
resistivity more than 10,000 Ω.m. The Moho is located between 25 and 35
km in the South Adamawa region.