| Title | Multi-dimensional and Geological Interpretation on Resistivity Imaging of Geothermal Systems in Kiejo-Mbaka SW Tanzania. Using Magnetotellurics Data: 2-D and 3-D Inversions and Comparison |
|---|---|
| Authors | Lucas B TUMBU, Ngereja M MGEJWA |
| Year | 2020 |
| Conference | World Geothermal Congress |
| Keywords | Multi-dimensional/Geology, MT 2-D and 3-D inversions, Kiejo-Mbaka geothermal field. |
| Abstract | This study is aiming at becoming acquainted with the resistivity method and different ways of performing multi-dimensional interpretation of magnetotellurics (MT) data for deep-lying subsurface investigations. The aim of modeling magnetotellurics data using all the two interpretational techniques is to compare results and establish which resistivity anomalies stand out irrespective of the dimensional inversion used. In this study results from 2-D and 3-D inversions are modeled and compared. The 3-D inversion, however, reveals much more consistent details than the 2-D inversions, confirming that the resistivity structures in the area are highly three-dimensional. All the inversion runs produced a resistive central body surrounded by conductive anomalous bodies. Four alteration zones have been inferred from different resistivity iso-surface, three conductive alteration zones inferred from the 10 Ωm iso-surface, and can be referred as low-T alteration zones. Two of them affect in the Mbaka fault foot wall, in the ridge eastern side of the Mbaka escarpment, another low-T alteration zone is located beneath the river plain SE of the Mbaka escarpment. A fourth alteration zone has been identified from the 50 Ωm iso-surface, probably correlated with a N-S fault passing near Lufundo manifestations; this zone could be related to high-T alteration. The assumption that, all the alteration zones should have affected the metamorphic basement has to be considered as per the available geological map. |