Abstract
The magnetotelluric method has been used in this work to compare the nature of the sedimentary-metamorphic contacts of the Douala and Kribi-Campo sub-basins in Cameroon. The results show that the sedimentary-metamorphic contact zones for the two sub-basins, marked by a subsidence of the low resistivity materials on the sedimentary formations and uplift of the high resistivity materials characterized by intrusive bodies of higher values of resistivity on the metamorphic formations, are structurally similar,. However, the very low values of resistivity of rocks in the Douala sub-basin is suggestive of high porosity, permeability and high level of saline ions dissociation leading to high conductivity. These rocks should be of unconsolidated sediments for the sedimentary formation and gneiss for the metamorphic formation. On the contrary, the very high values of resistivity for rocks in the Kribi-Campo sub-basin indicate the absence of free mobile electrons and ions and low porosity, permeability and non-conductivity. The sedimentary formation of this sub-basin should be composed of limestone and conglomerates rocks with some gneissic and unconsolidated granitic materials. The rocks in the metamorphic formation should be completely granitic in nature. The shallow depth of penetration of only 4 km of telluric current in the Douala sub-basin is enough evidence that the tectonic events responsible for the emplacement of this contact zone were limited to the earth crust. On the other hand, in the Kribi-Campo sub-basin the tectonic events should have originated from within the earth mantle as the depth of penetration of telluric current attains 150 km.
Highlights
Geological Settings 4° 00′N 4° 05′N 10° 00′E 2° 22′N 2° 26′N 9° 57′E 10° 41′E
Profile Y is oriented from West to East with the base station at Mangoulle and profile D is oriented from South to North with a base station at Bonepoupa I
For the purpose of interpretation and following the shape depicted in the maps, the colour codes vary from deep blue to grey for resistivity values ranging from[0] Ωm ≤ ρ ≤ 3 Ωm, from deep green to deep yellow for resistivity values ranging from 3 Ωm < ρ ≤ 18.0 Ωm and from orange to purple for resistivity values ranging from 18 Ωm < ρ ≤ 316 Ωm
Summary
The difficulties faced in the collection of data for the Douala sub-basin were related to the inaccessible nature of the basin due to the mangrove forest and the fact that the frequency range of the ECA resistivity meter is considered too high for the telluric current to penetrate the deep-seated structures given the high conductivity of sedimentary rocks in this area. The principal directions were chosen in the North-South and East-West cardinal directions.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
