<p>This study evaluates the geothermal potential of the Akiri Hot Spring (AHS) region, Middle Benue Trough (MBT), Nigeria, using airborne magnetic data. Advanced geophysical processing techniques were employed to analyze the subsurface structures and identify geothermal reservoirs of the region by revealing the fault zones, delineating the lithological variations, and mapping the structural discontinuities critical for assessing thermal energy prospects zones of the region. Qualitatively, the magnetic anomaly map reveals lithological variation with magnetic intensity values ranging − 31.4–117.3 nT. Low magnetic intensity values (< 23.7 nT) were found around the AHS region, while high-intensity values (> 78.2 nT) found in the north and eastern regions. Low Analytic Signal (AS) values (< 0.001 nT/m) were observed around the Akiri region, and they were linked to the alluvial sandstones of the Pliocene age, whereas higher AS values (> 0.007 nT/m) are revealed in the southeastern regions of the research area and it is an indicative of intrusive rock bodies. Quantitative investigation using spectral analysis reveals depth to top <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40517_2025_366_Article_IEq1.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="40" /> </InlineMediaObject> <EquationSource Format="TEX">$\left( {d_{{{\text{top}}}} } \right)$</EquationSource> <EquationSource Format="MATHML"><math> <mfenced close=")" open="("> <msub> <mi>d</mi> <mtext>top</mtext> </msub> </mfenced> </math></EquationSource> </InlineEquation> and depth to centroid <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40517_2025_366_Article_IEq2.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="28" /> </InlineMediaObject> <EquationSource Format="TEX">$\left( {d_{c} } \right)$</EquationSource> <EquationSource Format="MATHML"><math> <mfenced close=")" open="("> <msub> <mi>d</mi> <mi>c</mi> </msub> </mfenced> </math></EquationSource> </InlineEquation> (ranging from 0.587 ± 0.015 to 1.106 ± 0.038 km and 4.830 ± 0.048–6.150 ± 0.044, respectively). The calculated Curie point depth <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40517_2025_366_Article_IEq3.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="40" /> </InlineMediaObject> <EquationSource Format="TEX">$\left( {d_{{{\text{CP}}}} } \right)$</EquationSource> <EquationSource Format="MATHML"><math> <mfenced close=")" open="("> <msub> <mi>d</mi> <mtext>CP</mtext> </msub> </mfenced> </math></EquationSource> </InlineEquation> and heat flow ranges from 8.559 ± 0.046 to 11.380 ± 0.059 km and 124.700–129.6 mW/m<sup>2</sup>, respectively. A three-dimensional model integrating <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40517_2025_366_Article_IEq4.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="27" /> </InlineMediaObject> <EquationSource Format="TEX">$d_{{{\text{top}}}}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>d</mi> <mtext>top</mtext> </msub> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40517_2025_366_Article_IEq5.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="27" /> </InlineMediaObject> <EquationSource Format="TEX">$d_{{{\text{CP}}}}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>d</mi> <mtext>CP</mtext> </msub> </math></EquationSource> </InlineEquation> highlights a heat flow depression in the vicinity of AHS, where <InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40517_2025_366_Article_IEq5.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="27" /> </InlineMediaObject> <EquationSource Format="TEX">$d_{{{\text{CP}}}}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>d</mi> <mtext>CP</mtext> </msub> </math></EquationSource> </InlineEquation> has an average depth of approximately 10.2 km. High heat flow values in the AHS region indicate significant geothermal energy potential, possibly linked to magmatic activity, fault zones, or deep-seated thermal anomalies. Euler deconvolution indicates dominant E–W structural trends, with minor NE–SW orientations. Findings highlight substantial geothermal potential, driven by subsurface anomalies and faulting. This study enhances the understanding of geothermal systems in the MBT and provides a framework for exploring similar volcanic regions across Africa.</p>

Thermal energy assessment and structural modelling of the Akiri Hot Spring region, Middle Benue Trough, Nigeria, using magnetic data sets

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2025年11月12日

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Ayatu Ojonugwa Usman,
Ema Michael Abraham,
Joseph Sunday Nomeh,
Augustine Ifeanyi Chinwuko,
George-Best Azuoko,
Abraham Christipher Udoh

摘要

This study evaluates the geothermal potential of the Akiri Hot Spring (AHS) region, Middle Benue Trough (MBT), Nigeria, using airborne magnetic data. Advanced geophysical processing techniques were employed to analyze the subsurface structures and identify geothermal reservoirs of the region by revealing the fault zones, delineating the lithological variations, and mapping the structural discontinuities critical for assessing thermal energy prospects zones of the region. Qualitatively, the magnetic anomaly map reveals lithological variation with magnetic intensity values ranging − 31.4–117.3 nT. Low magnetic intensity values (< 23.7 nT) were found around the AHS region, while high-intensity values (> 78.2 nT) found in the north and eastern regions. Low Analytic Signal (AS) values (< 0.001 nT/m) were observed around the Akiri region, and they were linked to the alluvial sandstones of the Pliocene age, whereas higher AS values (> 0.007 nT/m) are revealed in the southeastern regions of the research area and it is an indicative of intrusive rock bodies. Quantitative investigation using spectral analysis reveals depth to top $\left( {d_{{{\text{top}}}} } \right)$ $(d_{top})$ and depth to centroid $\left( {d_{c} } \right)$ $(d_{c})$ (ranging from 0.587 ± 0.015 to 1.106 ± 0.038 km and 4.830 ± 0.048–6.150 ± 0.044, respectively). The calculated Curie point depth $\left( {d_{{{\text{CP}}}} } \right)$ $(d_{CP})$ and heat flow ranges from 8.559 ± 0.046 to 11.380 ± 0.059 km and 124.700–129.6 mW/m², respectively. A three-dimensional model integrating $d_{{{\text{top}}}}$ $d_{top}$ and $d_{{{\text{CP}}}}$ $d_{CP}$ highlights a heat flow depression in the vicinity of AHS, where $d_{{{\text{CP}}}}$ $d_{CP}$ has an average depth of approximately 10.2 km. High heat flow values in the AHS region indicate significant geothermal energy potential, possibly linked to magmatic activity, fault zones, or deep-seated thermal anomalies. Euler deconvolution indicates dominant E–W structural trends, with minor NE–SW orientations. Findings highlight substantial geothermal potential, driven by subsurface anomalies and faulting. This study enhances the understanding of geothermal systems in the MBT and provides a framework for exploring similar volcanic regions across Africa.