TITLE:
3D Modelling from New and Existing Gravity Data of an Intrusive Body in the Northern Part of Kribi-Campo Sub-Basin in Cameroon
AUTHORS:
Kue Petou Rokis Malquaire, Owona Angue Marie Louise, Njingti Nfor, Manguelle-Dicoum Eliezer
KEYWORDS:
Kribi-Campo Sub-Basin, Gravity Data, 3D Modelling, Spectral Analysis, Residual Anomaly
JOURNAL NAME:
International Journal of Geosciences,
Vol.8 No.8,
August
22,
2017
ABSTRACT: A new gravity survey was carried out in the northern part of the onshore Kribi-
Campo sub-basin in Cameroon. The data were incorporated to the existing
ones and then analyzed and modeled in order to elucidate the subsurface
structure of the area. The area is characterized in its north-western part by
considerably high positive anomalies indicative of the presence of a dense intrusive
body. We find, 1) from the analysis of the gravity residual anomaly
map, the high positive anomalies observed are the signature of a shallow
dense structure; 2) from the multi-scale analysis of the maxima of the horizontal
gradient, the structure is confined between depths of 0.5 km and 5 km;
3) from the quantitative interpretation of residual anomalies by spectral analysis,
the depth to the upper surface of the intrusive body is not uniform, the
average depth of the bottom is h1 = 3.6 km and the depths to particular sections
of the roof of the intrusion are h2 = 1.6 km and h3 = 0.5 km; 4) and the
3D modeling gives results that are suggestive of the presence of contacts between
rocks of different densities at different depths and a dense intrusive igneous
body in the upper crust of the Kribi zone. From the 3D model the dense
intrusive igneous block is surrounded by sedimentary formations to the
south-west and metamorphic formations to the north-east. Both formations
have a density of about 2.74 g/cm3. The near surface portions of this igneous
block lie at a depth range of 0.5 km to 1.5 km while its lower surface has a
depth range of 3.6 km to 5.2 km. The shape of the edges and the bottom of the
intrusive body are suggestive of the fact that it forms part of a broader structure
underlying the Kribi-Campo sub-basin with a great influence on the sedimentary
cover.