University of Twente Student Theses


Investigating Singo Granite anomaly in Kiboga, Central Uganda, using aeromagnetic and remote sensing data

Alade, Omotola Olufadekemi (2011) Investigating Singo Granite anomaly in Kiboga, Central Uganda, using aeromagnetic and remote sensing data.

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Abstract:The use of aeromagnetic survey as geophysical exploration technique has tremendously grown over the past few years. The study involves analysis of Aeromagnetic data and other remote sensing data sets in collaboration with field work to study the Singo granite in Kiboga area, Central Uganda. Geological mapping and magnetic susceptibility measurements were acquired during the field work. Aeromagnetic analysis was performed using Oasis Montaj software and several filtering techniques were executed i.e. analytical signal, vertical derivative, horizontal derivative, tilt derivative and 3D Euler deconvolution was used to characterize the magnetic sources. In addition, along three geological cross sections Potent software was used to model the Singo granite and its physical properties. The magnetic susceptibility measured along several walking traverses using a Kappa meter showed highly variable readings (0.01, 0.05, 0.23 and 1.19); similarly the measurements obtained in the areas covered by Singo granite have huge variations ranging from 0.03 to 5.72. However, on map deduced from aeromagnetic survey, areas covered by the metasediments are reflected by relatively low magnetic anomaly that is laterally extensive, the trace of outermost margin of the Singo granite is expressed by high frequency magnetic sources. The results from the SRTM DEM and Aster show that the drainage pattern is structurally controlled and filtering techniques (Oasis Montaj) indicate that NW-SE dykes are the dominant in the study area and they cut all the geological formations. In addition, the presence of echelon shaped deflections is an indication that this area is tectonically active. 3D Euler deconvolution results show magnetic sources as either linear features or clustered. The linear sources are oriented in either NW-SE or NE-SW, with NW-SE being widely distributed. Most of these magnetic sources are confined in the zone between 300-400 m but some at the boarders of the Singo granite are localized within shallow depths (100-200m). Further, the sub-parallel NE-SE is cut by the NW-SE linear structures, indicating a strong persistence of the NW-SE linear structures. Geologically, the NE-SW marks the Singo granite which majorly has no sources except along its outer margins and where it is cut through by the NW-SE linear structures. This indicates that the granite intrusion is much older than the faulting mechanism. The margin along the Singo granite possibly indicates lateritic material (alteration products i.e. tourmaline and hematite) marking the contact between the Singo granite and the host rock. The clustered but isolated magnetic sources are rather deep seated (500m) and have a rather poorly defined E-W trend. From 2D modelling in Potent, it is clear that the magnetic susceptibility of the metasediments is very low ranging from 0 to and 0.0005 whereas that of the granite is relatively slightly higher stable 0.003. These susceptibility values have the same order of magnitude for all the three profiles. From the potent, the source of magnetic anomaly at the periphery was determined. Keywords: Singo granite, aeromagnetic data, magnetic susceptibility, 3D Euler deconvolution, modelling.
Item Type:Essay (Master)
Faculty:ITC: Faculty of Geo-information Science and Earth Observation
Programme:Geoinformation Science and Earth Observation MSc (75014)
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