Assessment of the geothermal potential of Lake Baringo area using magnetic method
ABSTRACT Ground magnetic survey in Lake Baringo area was carried out to examine underlying geology in relation to anomalies in the magnetic field of the earth arising from the magnetic properties of subsurface lithology. This has been done to delineate areas associated with high temperature reservoir in the study area and establish if it relates with the occurrence of geothermal manifestations. The field stations were selected carefully along a profile in the study area and were positioned using Global Positioning System (GPS). The profile and station separation was set at about 800m and 500m respectively. The vertical magnetic field intensities were then measured using Flux Gate magnetometer. Data reduction was done to correct for diurnal and geomagnetic variations. Surfer 8.0 software was then used for gridding and to plot contour map to establish the anomaly signature of the area. Qualitative and quantitative interpretations has been done using the reduced vertical magnetic field intensity. Qualitative interpretation from the magnetic intesity contour map of the area showed that NE region is more dominated by long-wavelength component, that could be caused by deeper sources of magnetic anomalies. The Euler deconvolution method has been effectively used in estimating depth to the top of magnetic bodies. 2D Euler solutions revealed subsurface faulting activities and the presence of fluid-filled zones within the survey area which are marked by the absence of magnetic sources. Quantitative interpretation by forward modeling using Mag2dc software, has been used along selected profiles in the study area. The average modeled depth for the near surface magnetic anomaly sources of the area is 86.57m, while that of the deep seated anomaly sources is 349.25m. The bodies display susceptibility as high as 0.5301 SI units to as low as –0.841 SI units. The models show extensive lava flows. They are interpreted to be basaltic sills and dykes of different types based on geologic unit of the area. They may be possible heat source causing a thermal anomaly in the area west of Lake Baringo and such may have been magmatic intrusive that remained at the subsurface.