Ground Magnetic Mapping of Basement Structures of Maar Lake Tizong and Its Surroundings (Mandji/Wakwa, Adamawa, Cameroon)

Abstract

The Ngaoundéré area, marked by a complex geodynamic context, is characterized by ancient and recent tectonic activities, as well as intraplate volcanism linked to the Cameroon volcanic line (CVL). Ground magnetic mapping is an effective geophysical tool for detecting hidden faults or fractures and magnetic intrusions. The aim of this study is to investigate the basement of the maar Lake Tizong area in the Adamawa Plateau. Ground magnetic survey and eological field work have been carried out. Geological field work reveals that volcanic and granitic formations cropping out in the study area, and the main brittle structures trend NW‐SE. Qualitative and quantitative analyses were performed on magnetic data. Qualitative analysis uses a number of operators and mathematical filters, notably reduction to the equator, regional/residual separation, gradients, analytical signal, and tilt angle derivative. This enabled us to describe the anomalies globally, identify magnetic discontinuities and structures assimilated to fractures and faults, and produce a structural map of the magnetic lineaments. A quantitative analysis involves Euler deconvolution, 2D 3/4 modeling, and the source parameter index methods and makes it possible to assess the shapes and depths of the anomaly causative sources. As a result, the qualitative analysis identified several lineament directions, chiefly ESE‐WNW, ENE‐WSW, NE‐SW, and NW‐SE assimilated to brittle or ductile deformation. Structures trending NE‐SW and ENE‐WSW correlate with the regional fault of Ngaoundéré and are associated with the regional tectonic of the CVL. It revealed a cluster of solutions with depths greater than 100 m in the Mandjir area. These correspond to new magnetic discontinuities indicating the presence of intrusive bodies in the subsoil. However, NW‐SE and WNW‐ESE are linked to the major volcanic lava of Ngaoundéré and the orientation of Vina River. This work shows the presence of discontinuities favorable for fissural volcanism.