Determination of the Structural Lineaments in the Kribi-Campo-Ma’an Area from a Multi-Scale Analysis of Gravity Data Using the HGM and Euler 3D Deconvolution Approaches

Abstract

With the aim to produce a detailed structural map and then enhance the geological information of the south-western Cameroon, a field gravity study is carried out in the Kribi-Campo-Ma'an area (SW Cameroon). This study area is assumed to undergo pending active tectonics as witnessed by several earthquakes [1]. Besides, the area has been affected by some shears that gave rise to many major faults including the Kribi-Campo Fault (KCF). This N-S lineament is an active fault corresponding to the NW margin of the CC [2] [3] and related to the development of the Kribi-Campo basin. The gravity data analysis enables to highlight many deeply-seated structural features trending in the NE, NNE, N-S, NNW, NW and E-W directions in this region. The NW-SE trend is more strongly developed than the other identified trends and could have deeply affected the major NNE structure. The NNE-SSW to N-S fractures and faults which are local relays of the Kribi-Campo fault are related to the Kribi shear zone. The fairly good clustering observed on local maxima of the horizontal gradient magnitude enables to suggest that the contacts outlined have vertical to subvertical dips. However, a probable interpretation of these features is that they are vertical to subvertical faults which follow the aforementioned directions. The location of the study area in the gulf of Guinea suggests that it sustains tectonics related both to the equatorial and the south Atlantic oceans opening.How to cite this paper: Clotilde, O.A

Quantitative Interpretation of Gravity Anomalies in the Kribi-Campo Sedimentary Basin (South Cameroon) Based on Spectral Analysis and 2.5D Modelling: Structural Implications

“…[38] also mentioned the occurrence in the region of a strong extensional tectonic event that dates back to the Cretaceous. [8] on delineating the lineaments in south Cameroon obtained a structural map which shows that major tectonic events are responsible for the structural layout of this study zone. Furthermore, [9] presented a 3D model of another intrusive body located at about 40 km to the north of these two bodies.…”

“…[7] on delineating lineaments in the region, highlighted a series of deep and shallow faults traversing the area with a SW-NE dominating orientation. [8] [9] suggested the presence of high density intrusions in the subsurface of this study area from the analysis and interpretation of the maxima of horizontal gradient of the Bouguer anomalies. In presenting the interpreted structural map of the Kribi-Campo basin, [10] highlighted circular contacts indicating boundaries of intrusions in the Lolabe-Campo zone.…”

“…The model obtained highlights discontinuities between interfaces of contrasting densities at depths between 0.6 km, 2.5 km and 3.5 km. A closer look at Figure 7, from its geometrical position to its structural disposition coupled with the already known tectonic activities in the region [8] show that the tectonic events responsible for the emplacement, breaking up and separation of the intrusive igneous body into two bodies could first of all have been as a result of an upward vertical translational tectonic movement followed by an anticlockwise rotational faulting tectonic movement. This is in agreement with the results of [37], which indicate that the relief of the study area generally conserves the imprints of the phenomena of faulting tectonics.…”

“…The larger body on to the right, with a wider extend than the first is confined at depths of 0.6 km and 3.2 km approximately and occupies mainly the middle portion of the profile. The dislocation of the two body could be as a result of the geo-tectonic activities observed in the region which gave rise to various faulting systems[8] [9] [10][37].…”

Gravity study of the Douala sub-basin (Cameroon) using Euler 3D deconvolution, source edge detection (SED) and special function analysis

“…The Douala sedimentary sub-basin which constitutes the upper section of the Douala-Kribi/Campo sedimentary basin is one of the main basins of the Cameroon Atlantic basin located in the Gulf of Guinea. This sub-basin, unlike the adjacent Kribi/Campo sub-basin which has been subject to a number of geophysical studies [1][2][3][4][5][6][7][8][9][10][11][12], has in recent times recorded a few number of geophysical studies like those of [13][14][15]. Using audio magnetotellurics soundings, [12] were able to highlight two blocks with different morphologies on the basement-sedimentary transition zone around the eastern margin of the Douala basin and they as well estimated the total sedimentary thickness at 1.1 km.…”