Exploring Heat Sources Using Gravimetric Data: A Case Study of Magadi Geothermal Prospect, Kenya
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Date
2024-05-17
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Journal of Geoscience and Environment Protection, 2024, 12, 147-161
Abstract
Understanding the location of the subsurface heat sources is crucial for effi
cient geothermal resource exploration and exploitation. This study aimed to
investigate the faults and the depth to heat sources for a geothermal system in
Magadi, southern Rift Valley, through the integration of gravity mapping, 3D
Euler deconvolution, and spectral analysis. Gravity mapping is a powerful
geophysical method widely used to infer subsurface density variations, which
are indicative of geological structures and volcanic intrusions that can be po
tential heat sources. The Volcano-Tectonic and Fluvial-Deltaic Sedimentation
process of the Kenyan rift which encompasses the Magadi basin are responsi
ble for geomorphic and geologic processes in the area. Alkali lava sheets of
Magadi plateau trachytes covered with lacustrine sediments characterize 80%
of the area. Deeper is the Tanzanian craton basement, overlain by Pliocene to
Miocene volcanic and sedimentary rocks. A gravity survey with a data density
of 2.375 stations/km2 produced high-resolution anomaly and total horizontal
derivative maps showing gravity highs between −180 mGals to −174 mGals
along the eastern zone of the study area. A buried major fault trending N-S
was delineated in the mid-upper region of the area by Euler solutions at an
average depth of 350 meters. Deeper features associated with possible volcan
ic dykes and sills gave Euler depth ranges of 0.7 km to 2.2 km. Radial average
spectral analysis showed depth to the top of shallow and deep features at
2.4694 km and 5.827 km respectively. The correlation between gravity ano
malies, geological structures, and present hot springs supports the hypothesis
that volcanic processes have played a significant role in the development of
the geothermal system in the study area.
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DOI: 10.4236/gep.2024.125009