TITLE:
Magnetotelluric Investigation of the Geo-Tectonic Stability of Campo-Ma’an Area in South Cameroon
AUTHORS:
Njingti-Nfor , Owona Angue Marie Louise Clotilde, Kue Petou Rokis Malquaire, Bisso Dieudonné, Piameu Kwagag Jöel
KEYWORDS:
Magnetotelluric, Tectonics, Intrusions, Gravity-Gliding, Upwelling, Compression
JOURNAL NAME:
International Journal of Geosciences,
Vol.8 No.12,
December
19,
2017
ABSTRACT:
The magnetotelluric prospection method has been widely used in Cameroon
not only as a reconnaissance method for geophysical investigations but also to
determine the nature of the subsurface and the structural settings of the various
geological formations in the country that resulted from the global geo-tectonic
movements. The present study is aimed at employing the magnetotelluric
method to provide evidence on major tectonic dislocations which might have
led to the presence of plutonic intrusions in the cratonic structure of the Ntem
Complex as well as determining the nature of the contact between the sedimentary
Campo Basin and the metamorphic cratonic Ntem Complex. The
analyses and interpretations of iso-resistivity maps and geoelectric sections
from magnetotelluric data has enabled us to show that tectonic forces at contact
between the sedimentary Campo Basin and the metamorphic Ntem
Complex were of three different categories: gravity gliding, magmatic upwelling
and lateral compressions. The results of the action of these forces were the
development of vertical and sub-vertical faulting systems at Craton-Sedimentary
Basin contact and subsidence of overburden that appears to have also paved
the way for the setting-up of the Ntem River bed and its flood plains. This
river bed and its flood plains have been characterized as having a sedimentary
deposit depth of 500 m and width of 20 km. Meanwhile, the deep-seated contact
faulting systems within the two identified formations have varied fault
magnitudes with a maximum of 60 km. The relatively high apparently resistivity
values (up to1.0 kΩ•m) for the sedimentary and the very high values for
the metamorphic formations (up to and above 10.0 kΩ•m) suggest that the whole area is at present relatively geo-tectonically stable.