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Inferring the Subsurface Basement Depth and the Contact Locations from Aeromagnetic Data over Loum-Minta Area (Centre-East Cameroon)

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International Journal of Geosciences 2018年第7期9卷 435-459页

作者： Jean Aimé Mono Theophile Ndougsa-Mbarga Marcelin Bikoro Bi-Alou Jean Daniel Ngoh olivier ulrich owono Postgraduate School of Sciences Technologies & Geosciences University of Yaoundé I Yaoundé Cameroon Basical Sciences Teaching Department of Advanced Technical Teacher Training School University of Douala Douala Cameroon Department of Physics Advanced Teacher’s Training College University of Yaoundé I Yaoundé Cameroon Department of Earth Sciences Faculty of Science University of Maroua Maroua Cameroon

The present study aims to estimate the basement depth and contact locations, deduced from the available aeromagnetic data. The total intensity aeromagnetic (TMI) map was first corrected by the application of the reduction to equator technique. Different edge detection processes, for example, tilt angle derivative (TDR) and its total horizontal derivative (HD_TDR) as well as 3D-Euler deconvolution can determine the edges of these sources. These techniques were carried out on the aeromagnetic data of Minta region (the study area). A correlation was noticed between these techniques indicating that both of them can be attributed in delineating the general structural framework of the area. The aeromagnetic data analysis enables to highlight many deeply-seated structural features trending in the E-W, ENE-WSW and NE-SW directions in this region. The E-W trend is more strongly developed than the other identified trends. Moreover that, two depth methods were applied: analytic signal (AS) and source parameter imaging (SPI). They reflected similar results for estimating the basement depths. From both of them the depth ranges from 150 to 2800 m. Five methods (TDR, HD_TDR, 3D-Euler deconvolution, AS and SPI) for locating magnetic sources indicated that the depth of the basement rocks ranged between 150 and 3000 m as the average range. Also, the comparative study among the 2D magnetic modeling was established by one profile constructing.

关键词： Power Spectrum Multiscale Analysis (THDR_TDR AS) Euler Deconvolution SPI Basement

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Evidence of Structural Facts Inferred from Aeromagnetic Data Analysis over the Guider-Maroua Area (Northern Cameroon)

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International Journal of Geosciences 2017年第6期8卷 781-800页

作者： Jean Daniel Ngoh Théophile Ndougsa Mbarga Stéphane Patrick Assembe Arsène Meying olivier ulrich owono Tabod Charles Tabod Postgraduate School of Science Technology and Geosciences University of Yaoundé I Yaoundé Cameroon Department of Physics Advanced Teachers’ Training College University of Yaoundé I Yaoundé Cameroon School of Geology and Mining Engineering University of Ngaoundéré Meiganga Cameroon Faculty of Science University of Bamenda Bambili Cameroon

In this study, we performed some filters to highlight geological structures and/or features which are found in the igneous rocks, between the latitudes 9°45'N to 10°45'N and longitudes 13°15'E to 14°30'E. The application of the first vertical derivative (FVD) and the horizontal gradient magnitude (HGM) on a total magnetic data over the study area has led to put in evidence: 1) geological features as geological boundaries, faults, dykes, folds on the FVD map;2) abundant aeromagnetic lineaments probably fractures, dykes and contacts, ex-hibit a conjugate relationship suggesting a near NE and NW tectonic trends;3) existence of a possible prominent near E-W compression, characterized by a possible dextral displacement of geological formations by the shear movements;4) and the magnetic signature of the country rocks.

关键词： Magnetic Gradient Reduction to the Equator First Vertical Derivative Horizontal Gradient Magnitude Lineament Tectonic Trend

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Combination of Tilt-Angle and Euler Deconvolution Approaches to Determine Structural Features from Aeromagnetic Data Modeling over Akonolinga-Loum Area (Centre-East, Cameroon)

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International Journal of Geosciences 2017年第7期8卷 925-947页

作者： Justine Yandjimain Théophile Ndougsa-Mbarga Arsène Meying Marcelin Bikoro Bi-Alou Paul Claude Ngoumou Stéphane Patrick Assembe Jean Daniel Ngoh olivier ulrich Igor owono-Amougou Postgraduate School of Sciences Technologies & Geosciences University of Yaoundé I Yaoundé Cameroon Department of Physics Advanced Teacher’s Training College University of Yaoundé I Yaoundé Cameroon Department of Applied Geophysics Geology and Mining Exploitation College University of Ngaoundéré Ngaoundéré Cameroun Department of Earth Sciences Faculty of Science University of Maroua Maroua Cameroon Department of Physics Faculty of Science University of Bamenda Bambili Cameroon

Aeromagnetic data for center-east Cameroon between the latitudes 3.5° to 4.5°N and longitudes 12° to 12.5°E are used to further study the subsurface area of this part of the geological Province of Central Africa and the Congo Craton. The GIS and GEOSOFT v6.5 softwares are used to treat the data. This analysis enabled us to explore our study area from surface right to the base. The Tilt Angle method is used to delineate geological structures and to estimate the depth. The Euler’s deconvolution method is used to estimate the specific depth of structural contacts. We estimate the northern boundary of the Congo Craton and southern boundary of the Pan-African starting from 3°7'N of West to 3°75'N of East. Its depth is estimated around 2.6 km for deep and 0.1 km for shallow while the direction is WSW-ENE and the NW slope varies from 30° to 60°. We obtain that main and minor lineaments exist throughout, from the surface to the base of the area with their principal direction being SW-NE. We also obtain the vertical gradient contact and the quasihorizontal contact. This is proof of the subduction of the Pan-African belt under the Congo Craton due to the intense collision which caused the rejuvenation of the crust. The main consequence of this collision is the formation of pudding and fold structures, beginning from the superficial part right to the base and which caused the intrusion of schistose, chlorite-schist, quartzite in the micaschist and the intrusions of gneiss and garnetiferous schist in the migmatite. In our study, we highlight the presence of 37 major and 523 minor lineaments that localize the circulation of minerals. The probable slope of the lineaments in the northern part of the region varies from 30° to 60° in a SE direction while in the southern part, and it varies from 30° to 60° in a NW direction.

关键词： Tilt-Angle Euler Deconvolution Lineaments Fault Gradient Akonolinga-Loum

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2.5D Modelling of Aeromagnetic Data and their Mining Implications over the Ngaoundere Area (Adamawa Province, Cameroon)

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International Journal of Geosciences 2019年第2期10卷 173-192页

作者： Meying Arsène Gouet Daniel Hervé Ndougsa Mbarga Theophile Ndam Njikam Mouhamed owono Amougou olivier ulrich Igor School of Geology and Mining Engineering University of Ngaoundere Meiganga Cameroon Department of Petroleum Mining & Groundwater Resources Exploration Faculty of Mines and Petroleum Industries University of Maroua Maroua Cameroun Department of Physics Advanced Teacher’s Training College University of Yaoundé I Yaoundé Cameroon Postgraduate School of Science Technologies & Geosciences University of Yaoundé I Yaoundé Cameroon

This study is based on the analysis and interpretation of aeromagnetic data using version 8.4 of the Geosoft Oasis Montaj Software, to map the subsurface or deep geological structures that affected the geological formations of the Ngaoundere area. The use of the standard aeromagnetic methods made it possible to draw up the maps of the residual magnetic field reduced to the equator (RTE), the horizontal gradient (HG), the analytical signal (AS) and that of the Euler solutions (ED) to find the main magnetic facies corresponding to these structures. The geological formations of the studied area thus appear to be intensely fractured by a NE-SW (N45°E) and ENE-WSW (N70°E) main orientation fault system, the depth of which has been estimated by combining the three-analytical methods HG, AS and ED. Advanced magmatic map analysis revealed dikes associated with vertical faults in the studied area. The development of an interpretative geological map taking into account the basic geology, the deep faults, the identified dikes and the mineralization index made it possible to extract a correlation between geological structures and mineralization of the studied area. The 2.5D modelling of two magnetic profiles plotted on the reduced residual map at the equator was performed to approximate the geometry and depth of the dikes sector, which are potential sources of mineralization here.

关键词： Aeromagnetic Data Analytical Methods Faults Mineralization 2.5D Modelling

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2.5D Crustal Models Derived from Analytical Polynomial Separation Technique and Spectral Analysis of Gravity Data with Their Probable Gold Mineralization Migrations (Batouri, SE-Cameroon)

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Advances in Remote Sensing 2021年第1期10卷 1-24页

作者： Ngoumou Paul Claude Assembe Stephane Patrick owono Amougou olivier ulrich Igor Meying Arsene Yandjimaing Justine Ngoh Jean Daniel Pepogo Man-Mvele Augustin Didier School of Geology and Mining Engineering University of Ngaoundere Meiganga Cameroon Postgraduate School of Technology Science and Geoscience University of Yaoundé I Yaoundé Cameroon Department of Physics Faculty of Science University of Bamenda Bambili Cameroon Department of Physics Faculty of Science University of Yaoundé I Yaoundé Cameroon

Geophysical surveying is crucial in the investigation of mineral resources in poorly exposed areas such as SE-Cameroon, a region known for its gold mineral potential. In this paper, gravity survey is carried out in the Batouri area, SE-Cameroon based on land gravity data from the Centre-south Cameroon. Therefore, an analytical polynomial separation program, based on least-square fitting of a third-degree polynomial surface to the Bouguer anomaly map, was used to separate the regional/residual components in gravity data. This technique permitted to better understand the disposition of the deep and near surface structures responsible of the observed anomalies in the Batouri area. Spectral analysis and 2.5D modelling of two profiles P1 (SW-NE) and P2 (N-S) selected from the residual anomaly map provided depths to basement. These depths constrain the gravity models along the profiles, indicating a variable thickness of the sedimentary infill with an approximate anomaly of -33 mGal. The 2.5D model of the basement shows a gravity body, with a signature suggesting two close and similar masses, which characterize the quartz-bearing formations associated here to granite and gneiss. Our work highlights a main heavy gravity: Gwé-Batouri anomaly, containing the major part of auriferous deposits located along the NE-SW direction. Further, three tectonic sub-basins bounded by normal faults have been highlighted at Guedal, Gwé, and Bélimban, in the south of Guedal-Bélimban depression. They are associated with the extension tectonics, more or less vertical tangential cuts and accidents that have affected the r

关键词： Gravity Anomaly SE-Cameroon Polynomial Technique Spectral Analysis 2.5D Modelling Gold Mineralization Batouri Area

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