مجله ژئوفیزیک ایران

مجله ژئوفیزیک ایران

Qualitative and quantitative interpretation of high-resolution gravity data of Ewekoro, Southwest Nigeria using source parameter imaging and Euler deconvolution techniques

نوع مقاله : مقاله پژوهشی‌

نویسندگان
1 Associate Professor, Department of Physics, (Geophysics Unit), Federal University of Agriculture, Abeokuta, Nigeria
2 M.Sc. Graduate, Department of Physics, Federal University of Agriculture Abeokuta, Nigeria
3 Professor, Department of Physics, (Geophysics Unit) Federal University of Agriculture Abeokuta, Nigeria
4 Professor, Department of Environmental Management & Toxicology, Federal University of Agriculture Abeokuta, Nigeria
5 Lecturer, Department of Physics, Sikiru Adetona College of Education, Science and Technology, Omu-Ajose, Nigeria
چکیده
Geoscientists are interested in investigating the subsurface mineral resources such as crude oil through exploration of the Earth's subsurface. The availability and extent of these important commercial minerals can be ascertained by the characteristics of their geophysical properties through a geophysical survey in the area under investigation. Gravity method is a non-destructive geophysical method primarily used for locating the presence of solid minerals. This research work is aimed at using data coordinate interpolation techniques to extract information from aerogravity data obtained over Ewekoro in order to estimate the depth of the overburden thickness of the geological contact of the observed causative potential field anomaly. Hence, Source Parameter Imaging (SPI) and Euler deconvolution methods were applied on airborne gravity data of Ewekoro in both qualitative and quantitative approaches. The airborne gravity data sheets 260 and 279 acquired by the Bureau Gravimetrique International (BGI), through the Earth Gravity Model (EGM08) in 2008 were used. The raw gravity data recorded in digital format of X, Y and Z representing latitude, longitude and the Bouguer gravity values, respectively, were exported into Oasis Montaj software for qualitative and quantitative analysis. The datasets were gridded using the minimum curvature algorithm. Regional-residual separation was carried out to remove low frequency anomalies from the total field by applying a high-pass filter in sharpening the edges of the anomaly and enhancement. A Two-Dimensional Fast Fourier Transform (2D FFT) filtering technique was used in computing different derivative grids. The interpolated gravity map revealed a decrease in anomaly from SW to NE of the study area, with an anomaly range of 15–19 mGal. The SPI revealed a depth range of 235–698 m with the deeper gravity source concentrated in the central region and shallower source discovered in the SE of the study area. The 3D Euler depth estimates corresponding to Structural Index (SI) = 0 applied to the gravity data revealed a depth range of 132–692 m with a scattered Euler solution trending in NW, NE and SSE of the study area. The results for both methods indicate an average correlation in terms of their depths. The investigation revealed Bouguer anomaly thickness of Ewekoro trends in the SW–NE with significant depth for mineral exploration. The heterogeneity of the subsurface of the study area and the overburden thickness of Ewekoro trending in the NNE–NNW with an appreciable depth to harbour mineral resources were established.
 
کلیدواژه‌ها

موضوعات


عنوان مقاله English

Qualitative and quantitative interpretation of high-resolution gravity data of Ewekoro, Southwest Nigeria using source parameter imaging and Euler deconvolution techniques

نویسندگان English

Gideon Oluyinka Layade 1
Emmanuel Oluwatoyin Bamidele 2
Victor Makinde 3
Babatunde Saheed Bada 4
Hazeen Owolabi Edunjobi 5
1 Associate Professor, Department of Physics, (Geophysics Unit), Federal University of Agriculture, Abeokuta, Nigeria
2 M.Sc. Graduate, Department of Physics, Federal University of Agriculture Abeokuta, Nigeria
3 Professor, Department of Physics, (Geophysics Unit) Federal University of Agriculture Abeokuta, Nigeria
4 Professor, Department of Environmental Management & Toxicology, Federal University of Agriculture Abeokuta, Nigeria
5 Lecturer, Department of Physics, Sikiru Adetona College of Education, Science and Technology, Omu-Ajose, Nigeria
چکیده English

Geoscientists are interested in investigating the subsurface mineral resources such as crude oil through exploration of the Earth's subsurface. The availability and extent of these important commercial minerals can be ascertained by the characteristics of their geophysical properties through a geophysical survey in the area under investigation. Gravity method is a non-destructive geophysical method primarily used for locating the presence of solid minerals. This research work is aimed at using data coordinate interpolation techniques to extract information from aerogravity data obtained over Ewekoro in order to estimate the depth of the overburden thickness of the geological contact of the observed causative potential field anomaly. Hence, Source Parameter Imaging (SPI) and Euler deconvolution methods were applied on airborne gravity data of Ewekoro in both qualitative and quantitative approaches. The airborne gravity data sheets 260 and 279 acquired by the Bureau Gravimetrique International (BGI), through the Earth Gravity Model (EGM08) in 2008 were used. The raw gravity data recorded in digital format of X, Y and Z representing latitude, longitude and the Bouguer gravity values, respectively, were exported into Oasis Montaj software for qualitative and quantitative analysis. The datasets were gridded using the minimum curvature algorithm. Regional-residual separation was carried out to remove low frequency anomalies from the total field by applying a high-pass filter in sharpening the edges of the anomaly and enhancement. A Two-Dimensional Fast Fourier Transform (2D FFT) filtering technique was used in computing different derivative grids. The interpolated gravity map revealed a decrease in anomaly from SW to NE of the study area, with an anomaly range of 15–19 mGal. The SPI revealed a depth range of 235–698 m with the deeper gravity source concentrated in the central region and shallower source discovered in the SE of the study area. The 3D Euler depth estimates corresponding to Structural Index (SI) = 0 applied to the gravity data revealed a depth range of 132–692 m with a scattered Euler solution trending in NW, NE and SSE of the study area. The results for both methods indicate an average correlation in terms of their depths. The investigation revealed Bouguer anomaly thickness of Ewekoro trends in the SW–NE with significant depth for mineral exploration. The heterogeneity of the subsurface of the study area and the overburden thickness of Ewekoro trending in the NNE–NNW with an appreciable depth to harbour mineral resources were established.

کلیدواژه‌ها English

Potential field
gravity
Bouguer
mineral
depth
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