检索结果-南通市图书馆

Interpretation of locally high gravity anomalies using terrestrial gravity data in Bagodo, North Cameroon

Earth and Planetary Physics 2022年第4期6卷 378-384页

作者： Apollinaire Bouba Kasi Njeudjang Loudi Yap Bouba Saidou Joseph Kamguia tabod charles tabod Department of Physics Higher Teachers’Training CollegeUniversity of MarouaCameroon Department of Quality Industrial Safety and Environment National Advanced School of Mines and Petroleum IndustriesUniversity of MarouaCameroon Research Laboratory in Geodesy National Institute of CartographyYaoundéCameroon Department of Physics Faculty of ScienceUniversity of MarouaCameroon Department of Physics Faculty of ScienceUniversity of Yaounde ICameroon

In this work,we interpreted gravity data to determine the structural characteristics responsible for high-gravity anomalies in Bagodo,North Cameroon.These anomalies had not previously been characterized through a local study.Thus,we undertook a regional-residual separation of the gravity anomalies by using the polynomial method.Geophysical signatures of near-surface small-extent geological structures were revealed.To conduct a quantitative interpretation of the gravity anomalies,one profile was drawn on a residual Bouguer anomaly map and then interpreted by spectral analysis,the ideal body solution,and 2.5-dimensional modeling.Our results showed that the intrusive body in the Bagodo area consists of two trapezoidal blocks.The first and second blocks have roofs approximately 7.5 and 14 km deep,respectively,whereas their bases are approximately 17 km deep.These values are in agreement with those obtained by the ideal body solution,which showed two cells with a density contrast of 0.3 g·cm^(−3) in comparison with the surrounding rocks.The density of this body was estimated to be approximately 3 g·cm^(−3).The topography of these rocks showed that they are basaltic rocks that would have cooled in fracture zones as an intrusion.

关键词： spectral analysis ideal body solution 2.5-dimensional modeling

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Applying Source Parameter Imaging (SPI) to Aeromagnetic Data to Estimate Depth to Magnetic Sources in the Mamfe Sedimentary Basin

引用

International Journal of Geosciences 2024年第1期15卷 1-11页

作者： Eric N. Ndikum charles T. tabod Department of Physics HTTC Bambili The University of Bamenda Bamenda Cameroon Department of Fundamental Sciences Higher Technical Teacher Training College (HTTTC) Bamenda Cameroon Department of Physics University of Yaoundé 1 Yaoundé Cameroon Department of Physics Faculty of Science The University of Bamenda Bamenda Cameroon

Aeromagnetic data over the Mamfe Basin have been processed. A regional magnetic gridded dataset was obtained from the Total Magnetic Intensity (TMI) data grid using a 3 × 3 convolution (Hanning) filter to remove regional trends. Major similarities in magnetic field orientation and intensities were observed at identical locations on both the regional and TMI data grids. From the regional and TMI gridded datasets, the residual dataset was generated which represents the very shallow geological features of the basin. Processing this residual data grid using the Source Parameter Imaging (SPI) for magnetic depth suggests that the estimated depths to magnetic sources in the basin range from about 271 m to 3552 m. The highest depths are located in two main locations somewhere around the central portion of the study area which correspond to the area with positive magnetic susceptibilities, as well as the areas extending outwards across the eastern boundary of the study area. Shallow magnetic depths are prominent towards the NW portion of the basin and also correspond to areas of negative magnetic susceptibilities. The basin generally exhibits a variation in depth of magnetic sources with high, average and shallow depths. The presence of intrusive igneous rocks was also observed in this basin. This characteristic is a pointer to the existence of geologic resources of interest for exploration in the basin.

关键词： Mamfe Basin Aeromagnetic Data Source Parameter Imaging (SPI) Depth to Magnetic Sources

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Geophysical and Geotechnical Investigations of a Landslide in Kekem Area, Western Cameroon

引用

International Journal of Geosciences 2012年第4期3卷 780-789页

作者： Pouyon Dieudonné Epada Ganno Sylvestre tabod charles tabod University of Yaoundé I University of Yaounde I National Civil Engineering Laboratory

Geophysical and geotechnical surveys were conducted in the Western Cameroon (Kekem area) following a landslide on argillaceous material in order to understand the triggering processes and mechanisms of this landslide and to assess the stability of the slope. The geophysical soundings consisting of vertical electrical soundings with the Schlumberger electrode array configuration were carried out to monitor the behaviour of electrical resistivity in the landslide. Geoelectrical data showed a zone of low resistivity values identified as a clayey sand-filled aquifer. This aquifer played an important role in the triggering process of the landslide. Geotechnical soundings showed that the aquifer had a thickness of 7.0 m. The depth from the landslide crest level to the failure surface reached 3.0 m and 20.6 m. Laboratory tests were then carried out in order to evaluate the cohesion of the soil and the angle of internal friction, and to calculate the safety factor in view of making a stability analysis. The laboratory results exhibited a soil with low consistency, almost doughy. The mean value of the safety factor (1.4) been lower than the slope stability coefficient (1.5), revealed that the slope is unstable, likely to know at any moment a reactivation of the slide. This study showed that electrical soundings coupled with geotechnical surveys are useful tools for the characterization of landslides.

关键词： Landslide Resistivity Argillaceous Material Basal Undercutting Kekem Cameroon

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Crustal structure beneath Cameroon from EGM2008

引用

Geodesy and Geodynamics 2014年第1期5卷 1-10页

作者： Ngatchou Heutchi Evariste Liu Genyou tabod charles tabod Kamguia Joseph Nguiya Severin Tiedeu Alain KE Xiaoping State Key Laboratory of Geodesy and Earth's Dynamics Institute of Geodesy and GeophysicsChinese Academy of Sciences Department of Physics Faculty of ScienceUniversity of Yaoundé I National Institute of Cartography Industrial Engineering Faculty University of Douala Ecole Nationale Supérieure Polytechnique Université de Yaoundé I

We used the Earth Gravitational Model （EGM2008） data sets to analyze the regional gravity anoma- lies and to study the underground structures in Cameroon. We first created a high-resolution Free-Air anomaly database, then corrected the gravity field of the topographic effect by using ETOPO1 DEM with a resolution of 0.01~ to obtain the Bouguer anomaly, then applied a multi-scale wavelet-analysis technique to separate the gravity-field components into different parts of shallow-to-deep origins, and finally used the logarithmic power spectrum technique to obtain detailed images and corresponding source depths as well as certain lateral inho- mogeneity of structure density. The anomalies of shallow origin show successive elongated gravity ＂highs＂ and ＂lows＂ attributable to subsurface Tertiary and lower Cretaceous undulations. Our results are in good agreement with previous investigations.

关键词： Cameroon EGM2008 gravity anomalies wavelet transform power spectrum crustal structure

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Gravity Interpretation of the Cameroon Mountain (West Central Africa) Based on the New and Existing Data

引用

International Journal of Geosciences 2011年第4期2卷 513-522页

作者： Jean Victor Kenfack Jean Marie Tadjou Joseph Kamguia tabod charles tabod Ateba Bekoa 不详

A new gravity survey of the Mount Cameroon area has enabled the definition of four major gravimetric do- mains, which coincide with the recognized structural units. In order to determine the nature of superficial and deep structures in this mountainous zone, new gravity data have been processed. These new gravity data was integrated to existing gravity data to propose the new complete Bouguer anomaly map of the region, and then to show major characteristics of the Bouguer gravity of this area. The interpretation of gravity patterns (bouguer maps) in terms of geological data, shows that the Mount Cameroon zone belongs to a wide positive anomaly;these anomalies display complex gravity domains, which seem to be similar to that due to major structural units in the region and volcanic activity of the mountain. In the mountain active zone in particular (between 2000 and 3800 m of altitude), the new anomalies map shows high gravity anomalies (from 11 to 60 mgal), coupled with low gravity at some stations (in the summit, 4060 m) where gravity anomaly is about –30 mgal. The steep WNW-ESE gravity gradients observed on the gravity maps mark the transition between positive in the south and negative anomalies.

关键词： Mount Cameroon CVL Gravity Anomalies Bouguer Anomalies

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Geoelectric Investigation for Groundwater Exploration in YaoundéArea, Cameroon

引用

International Journal of Geosciences 2012年第3期3卷 640-649页

作者： William Assatsé. Teikeu Philippe Nouck Njandjock Théophile Ndougsa-Mbarga tabod charles tabod Department of Physics Advanced Teachers’ Training College University of Yaounde I P.O. Box 47 Yaounde Cameroon Department of Physics Faculty of Science University of Yaounde I P.O. Box 812 Yaounde Cameroon

Yaounde zone is originally characterized by the small number of aquifers and bad renewal capacity. Within the frame-work of the emergency program which aims at supplying the city with drinking water, seventeen Vertical Electrical Soundings (VES) were carried out using Schlumberger configuration in parts of Yaounde (latitude 3o- 5oN and longi- tude 11o-13oE) to determine the nature and thickness of aquifer zone and necessary geoelectrical parameters. Four to five geoelectric layers were delineated from the survey area. The first layer is the topsoil and has resistivity values ranging from 13 - 216 Ω·m and thickness is between 0.1 - 6 m. The second layer made up of clay sand and laterite has resistivity values ranging between 23 and 923 Ω·m and thickness ranged from 1 and 40 m. The third and fourth geoelectric layers consisting of clay and gneiss/migmatite with thickness varying from 1.7 - 63.3 m correspond to an aquifer horizon. Resistivity values of the aquifer ranges from 4 to 9215 Ω·m. The study indicates that average depth of the aquifer is 20 m and average thickness of the aquifer is 55 m. Soundings curves suggest several four layered geoelectrical sections KH, KQ, HK type and some five layered sections of the HKH, KHK types. KH type is dominant and can be used as reference for future studies. The resistivity survey reveals that the parameters obtained through interpretation of VES curves corroborate the litho logs of boreholes from the area.

关键词： Aquifer Geoelectrical Section Vertical Electrical Sounding (VES) Yaoundé

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Estimation of Curie Point Depth (CPD) across the Pan African Belt in Northern Cameroon from Aeromagnetic Data

引用

Open Journal of Earthquake Research 2020年第3期9卷 217-239页

作者： Jean Daniel Ngoh Théophile Ndougsa Mbarga Kevin Mickus Yara Tarek 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 Department of Geography Geology and Planning Missouri State University Springfıeld MO USA Exploration Department Egyptian Petroleum Research Institute Cairo Egypt Faculty of Science University of Bamenda Bambili Cameroon

The depth to the Curie isothermal point (CPD) was estimated using aeromagnetic data from northern Cameroon. The CPD was estimated using a two-dimensional power density spectral analysis of nineteen 30 × 30 km blocks over a series of Neoproterozoic lithologies associated with the Pan African orogeny. The results show that there are two main regions characterized by the CPD analysis: 1) Shallow depths (~6.37 - 10.09 km) which are located in several regions including the northern portions of the study area (toward the regions of Hina Marbak, Gawel and northern Moutouroua), the southeast (Kaele region), the south (Guider) and the southwest (Mayo Oulo), and 2) deeper depths (~10.68 - 13.72 km) are located in the northeast (Mindif) and southwest (southern Moutouroua, Guider and Bossoum). The shallow depths can be related to two tectonic regimes: 1) the West-Central African Rift System with northeast-trending strike-slip faults emanating from the Gulf of Guinea and 2) the Cameroon Volcanic Line. However, the ultimate source of these shallow regions is interpreted to be related to the Cameroon Volcanic Line based on low seismic velocities imaged by recent broadband seismic studies which are concentrated along the northeast-trending strike-slip faults. An additional finding using the CPD depths, a Curie isothermal temperature of 580°C and a one-dimensional heat flow model, was heat-flow values ranging from 105.68 to 227.63 mW/m2, which are above average global heat flow values and are therefore indicative of potential geothermal resources.

关键词： Magnetic Anomaly Spectral Analysis Curie Point Depth Geothermal Gradi-ent Heat Flow

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Subsurface Structural Mapping Using Combined Terrestrial and Grace Gravity Data of the Adamawa Plateau (North-Cameroon)

引用

International Journal of Geosciences 2017年第7期8卷 869-887页

作者： Bouba Apollinaire Kamguia Joseph tabod charles tabod Yap Loudi Nouayou Robert Kande Houetchak Ludovic Oyoa Valentin Department of Physics Higher Teachers’ Training College University of Maroua Maroua Cameroon Department of Physics Faculty of Science University of Yaounde I Yaounde Cameroon National Institute of Cartography Yaounde Cameroon

In order to analyze and determine the geological structures of the Adamawa plateau, the terrestrial gravity data were combined to data computed from GGM02C gravity model. The dense gravity net obtained were further introduced into qualitative and quantitative interpretations. The resulting Bouguer anomaly map obtained from combined data shows NE-SW direction which nearly coincides with the main direction of the fractures affecting the basement in the region and indicates strong gradients marking the presence of discontinuities between heavy and negative gravity anomaly. In order to conduct the quantitative interpretation of the combined gravity data, three profiles were drawn on the residual Bouguer anomaly map and therefore were interpreted using spectral analysis method and 3D density inversion. The knowledge of the depth and density of the geological structures show an uplift of dense rocks under the granite-gneiss substratum. This dense material found in the ENE-WSW direction of the Adamawa Plateau is interpreted as basaltic intrusion probably resulting from tectonic processes. According to this study, the depths of 3.83 km and 9.62 km are the new values of depths obtained for futures investigations in the Adamawa plateau.

关键词： GGM02C Adamawa Plateau Bouguer Anomaly 3D Density Model Spectral Analysis

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Understanding the Meaning of the Positive Bouguer Anomaly of Waza (Northernmost Cameroon, Central Africa)

引用

Journal of Geoscience and Environment Protection 2019年第6期7卷 55-65页

作者： Eyike Albert Basseka charles Antoine Lordon Djieto Anatole Eugene Nguimbous-Kouoh Jean Jacques Zanga-Amougou Alain tabod charles tabod Department of Physics Faculty of Science University of Douala Douala Cameroon Department of Earth Science Faculty of Science University of Douala Douala Cameroon Department of Geology Faculty of Science University of Buea Buea Cameroon Department of Gas and Petroleum Exploration Institute of Mines and Petroleum Industries University of Maroua Maroua Cameroon Department of Physics Faculty of Science University of Yaoundé 1 Yaoundé Cameroon

Gravity and magnetic data were analyzed in conjunction with available geological data to determine the origin of observed positive gravity anomaly at Waza and its possible relationship to mafic intrusions. The data analysis includes the construction of a Bouguer gravity anomaly, isostatic residual gravity anomaly, total magnetic gradient and Euler solutions maps, and two and one-half dimensional gravity models. A positive gravity anomaly that occurs in Waza has amplitude of 35 mGal and can be separated into two parts. The top of the disturbing body causing the anomaly cannot be deeper than 4 km. We believe the anomaly is probably caused by a body of basaltic rocks lying at the upper surface of the Precambrian basement and originate from a self-propagating disturbance of magmatic loads on a pre-existing zone of lithospheric weakness. Melt migration might have been aided by tectonic and flexural stresses, such that the intrusion is limited in extent to the melting region of the plume and did not reach the surface. The model calculated to satisfy the observed anomaly consists of a 2.5 Km-thick slab underlain by a 10.5 km deep column. This model is interpreted to represent a sheet or saucer-like mafic intrusion that has a thick deep feeder. Detailed geophysical studies would be necessary to locate any possible economic occurrences.

关键词： Northern Cameroon Waza Bouguer High Total Magnetic Gradient Basaltic Intrusion

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Interpretation of Gravity Anomalies by Multi-Scale Evaluation of Maxima of Gradients and 3D Modelling in Bipindi Region (South-West Cameroon)

引用

International Journal of Geosciences 2014年第12期5卷 1415-1425页

作者： Fidèle Koumetio Donatien Njomo Constant Noutchogwe Tatchum Alain Pierre Kamga Tokam tabod charles tabod Eliezer Manguelle-Dicoum Department of Physics Faculty of Science University of Yaounde I Yaounde Cameroon Department of Physics Faculty of Science University of Dschang Dschang Cameroon Department of Physics University of Bamenda Bamenda Cameroon School of Geosciences University of Witwatersrand Johannesburg South Africa

The gravity maps display, in Bipindi zone, local oval culminations of low anomalies indicative of a presence of intrusive light body in a subsurface but the nature, the form and the position of this body are still unknown. The analyses of established gravimetric anomaly maps, the multi-scale evaluation of maxima of gradients and the quantitative interpretation of residual anomalies by 3D modelling permit characterizing the intrusive light body situated at Bipindi. The multi-scale evaluation of maxima of gradients shows that the modelling of the intrusive light body of Bipindi can be done without the problem of interference of anomalies from different sources. The 3D model of Bipindi zone shows two dissymmetrical blocks of the same type of rock with a density contrast of -0.095 g·cm-3 in comparison with the density of the surrounding metamorphic rocks. The two blocks are at a distance about 3 km from one to another. The upper surfaces of these blocks lie at a depth between 1 and 2 km. Their lower surfaces have two landings;one lies at a depth of about 8 km and another at a depth about 14 km. A consideration of the density of the modelled body, of the ranges of densities of specific rocks present in the general region indicates that the body may be composed of nepheline syenites. The intrusive body of Bipindi is situated in a senestral shear zone. The area situated between the two blocks of this intrusive body may be indicated for a detail study in the domain of mineral research.

关键词： Gravity Anomalies Maxima of Gradients Residual Anomalies Modelling

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：