Evaluation of geological structures and geothermal resources in the North Tanzania Volcanic area using remote sensing and gravity data analysis
Abstract
Problems Statement and Purpose. Northern Tanzania Volcanic terrain has been a subject of evaluation for geothermal potential in the last four decades. The region is characterized by Neogene to Recent volcanic and tectonic activities. This preliminary study based on remote sensing, water chemistry, gravity data, geological structures and volcanic centers distribution reports the geothermal manifestations identified and discusses the implications on geothermal fluid pathways. Oxygen-hydrogen isotope data from water samples indicate that there were involved in the hydrothermal system.
Tectono-Volcanic Structures. The Northern Tanzania Divergence (NTD) area characterized by Neogene to Recent volcanic and tectonic activities. Recent volcanic and tectonic activities are ash cone and lava dome eruption at the floor of Meru crater a century ago, dyke intrusion and volcanic eruption south of Gelai volcano, and Oldoinyo-Lengai volcano, respectively. Fumarolic activities and hot springs are dominant in a relatively young volcanic area to the north-eastern and northern part of the NTD.
Data and Methods. Shuttle Radar Topography Mission (SRTM), Landsat 8 Operational Land Imager (OLI) image, water isotope analysis and gravity data were used to extract and analyze the surface and subsurface geological lineaments and map the hydrothermal alteration zones in the study area. The hydrothermal alteration is used to evaluate and identify the permeable structures. Analysis and interpretation of the length and trends of extracted lineaments were used to investigate the tectonic evolution. Geological map of a study area was digitized from the existing geological maps and the age of rocks to delineate volcanic activity and associated lineaments based on the age of the lithological domain. Digital image processing was applied to enhance the visual interpretation. Gravity data were used to give insight into the subsurface structure in the study area.
Results and Discussion. The higher δ 18O values and large deviation from meteoric water lines suggest that is due to the interaction of fluids with host rocks at elevated temperatures. These are consistent with open structures that act as conduits for fluid flow. The potential field gravity data reveal a basin-like structure trending in the NNW direction. The gravity data show that the basement units gradually deepen towards the central part and that it is controlled by two main fault systems that trend N-S and NW-SE respectively. The gravity data presented here provides new constraints on the tectonic evolution and geothermal resources of the study area.
Downloads
References
Abdelsalam, M., Stern, R.J., Berhane, W.G. (2000). Mapping gossans in arid environments with Landsat TM and SIR-C images: the Beddaho alteration zone in northern Eritrea. Journal of African Earth Sciences, 30 (4): 903–916. DOI: https://doi.org/10.1016/S0899-5362(00)00059-2
Albaric, J., Déverchére, J., Perrot, J., Jakovlev, A., Deschamps, A. (2010). Contrasted Seismogenic and Rheological Behaviours from Shallow and Deep Earthquake Sequences in the North Tanzanian Divergence, East Africa. Journal of African Earth Sciences, 58 (5): 799–811. DOI: https://doi.org/10.1016/j.jafrearsci.2009.09.005
Ali, A., Pour, A. (2014). Lithological Mapping and Hydrothermal Alteration Using Landsat 8 Data: A Case Study in Ariab Mining District, Red Sea Hills, Sudan. International Journal of Sciences: Basic and Applied Research, 3 (3): 199–208. DOI: https://doi.org/10.14419/ijbas.v3i3.2821
Baker, B.H., Mohr, P.A., Williams, L.A.J. (1972). Geology of the Eastern Rift System of Africa. Geological Society of America, (136) 67. DOI: https://doi.org/10.1130/SPE136
Bilim, F. (2007). Investigations into the tectonic lineaments and thermal structure of Kutahya-Denizli region, western Anatolia, from using aeromagnetic, gravity and seismological data. Physics of the Earth and Planetary Interiors, 165 (3–4): 135–146. DOI: https://doi.org/10.1016/j.pepi.2007.08.007
Björnsson, H. (2010), Understanding jökulhlaups: from tale to theory. Journal of Glaciology, 56 (200), 1002–1010. DOI: https://doi.org/10.3189/002214311796406086
Calvin, W.M., Littlefield, E.F., Kratt, C. (2015). Remote Sensing of Geothermal-Related Minerals for Resource Exploration in Nevada. Geothermics, 53: 517–526. DOI: https://doi.org/10.1016/j.geothermics.2014.09.002
Chavez, P.S., Sides, S.C., Anderson, J.A. (1991). Comparison of three different methods to merge multi-resolution and multi-spectral data: Landsat TM and SPOT panchromatic. Photogrammetric Engineering and Remote Sensing, 56: 459–467.
Dawson, J.B. (1992). Neogene Tectonics and Volcanicity in the North Tanzania sector of the Gregory Rift Valley: contrasts with the Kenya sector. Tectonophysics, 204 (1–2): 81–92. DOI: https://doi.org/10.1016/0040-1951(92)90271-7
Dawson, J.B. (2008). The Gregory Rift Valley and Neogene-Recent Volcanoes of Northern Tanzania. Geological Society of London, 33 (1–91).
Ebinger, C.J., Weinstein, A., Oliva, S.J., Roecker, S., Tiberi, C., Aman, M., Lambert, C., Witkin, E., Albaric, J., Gautier, S., Peyrat, S., Muirhead, J.D., Muzuka, A.N.N., Mulibo, G., Kianji, G., Wambura, R.F., Msabi, M., Rodzianko, A.R., Hadfield, R., Illsley-Kemp, F., Fischer, T.P. (2017). Fault-Magma Interactions during Early Continental Rifting: Seismicity of the Magadi-Natron-Manyara Basins. Geochemistry, Geophysics, Geosystems, 18 (10): 3662–3686. DOI: https://doi.org/10.1002/2017GC007027
Fairhead, J.D. (1976). The Structure of the Lithosphere beneath the Eastern Rift, East Africa, Deduced from Gravity Studies. Tectonophysics, 30 (3–4): 269–298. DOI: https://doi.org/10.1016/0040-1951(76)90190-6
Fairhead, J.D. (1980). The Structure of the Cross-Cutting Volcanic Chain of Northern Tanzania and Its Relation to the East African Rift System. Tectonophysics, 65 (3–4): 193–208. DOI: https://doi.org/10.1016/0040-1951(80)90074-8
Foster, A.N., Ebinger, C.J., Mbede, E., Rex, D. (1997). Tectonic development of the northern Tanzanian sector of the East African Rift System. Journal of Geological Society, London, 154: 689–700. DOI: https://doi.org/10.1144/gsjgs.154.4.0689
Franzson, H., Kristjansson, B.R., Gunnarsson, G., Björnsson, G., Hjartarson, A., Steingrimsson, B., Gunnlaugsson, E., Gislason, G. (2005). The Hengill-Hellisheiði Geothermal Field. Development of a Conceptual Geothermal Model. In Proceedings of the World Geothermal Congress, Antalya, Turkey. https://www.geothermal-energy.org/pdf/IGAstandard/WGC/2005/2632.pdf
Himematsu, Y., Furuya, M. (2015). Aseismic Strike-Slip Associated with the 2007 Dike Intrusion Episode in Tanzania. Tectonophysics, 656: 52–60. DOI: https://doi.org/10.1016/j.tecto.2015.06.005
Hutchison, W., Mather, T.A., Pyle, D.M., Biggs, J., Yirgu, G. (2015) Structural controls on fluid pathways in an active rift system: a case study of the Aluto volcanic complex. Geosphere, 11 (3): 542–562. DOI: https://doi.org/10.1130/GES01119.1
Le Gall, B., Nonnotte, P., Rolet, J., Benoit, M., Guillou, H., Mousseau-Nonnotte, M., Albaric, J., Deverchère, J. (2008). Rift Propagation at Craton Margin. Distribution of Faulting and Volcanism in the North Tanzanian Divergence (East Africa) during Neogene Times. Tectonophysics, 448 (1–4): 1–19. DOI: https://doi.org/10.1016/j.tecto.2007.11.005
Leat, P.T. (1991). Volcanological development of the Nakuru area of the Kenya rift valley. Journal of African Earth Sciences, 13 (3–4): 483–498. DOI: https://doi.org/10.1016/0899-5362(91)90111-B
Lee, H., Fischer, T.P., Muirhead, J.D., Ebinger, C.J., Kattenhorn, S.A., Sharp, Z.D., Kianji, G., Takahata, N., Sano, Y. (2016). Massive and Prolonged Deep Carbon Emissions Associated with Continental Rifting. Nature Geoscience, 9 (2): 145–149. DOI: https://www.nature.com/articles/ngeo2622#affil-auth
Loughlin, W.P. (1991). Principal Component Analysis for Alteration Mapping. Photogrammetric Engineering and Remote Sensing, 57 (9): 1163–1169. DOI: https://www.asprs.org/wpcontent/uploads/pers/1991journal/sep/1991_sep_1163-1169.pdf
Ma, Z.J., Gao, X.L., Song, Z.F. (2006). Analysis and tectonic interpretation to the horizontal gradient map calculated from Bouguer gravity data in the China mainland. Chinese Journal of Geophysics, 49 (1): 106–114. DOI: https://doi.org/10.1002/cjg2.816
Mana, S., Furman T., Turrin B.D., Feigenson M.D., Swisher, C.C. (2015). Magmatic Activity across the East African North Tanzanian Divergence Zone. Journal of the Geological Society, 172 (3): 368–389. DOI: https://doi.org/10.1144/jgs2014-07
Mia, M.B., Fujimitsu, Y. (2013). Landsat Thermal Infrared Based Monitoring of Heat Losses from Kuju Fumaroles Area in Japan. Procedia Earth and Planetary Science, 6: 114–120. DOI: https://doi.org/10.1016/j.proeps.2013.01.016
Mitchell, H.B. (2010). Image Fusion: Theories, Techniques and Applications, Springer: Berlin Heidelberg, 247 pp.
Mollel, G.F., Swisher, C.C., Feigenson, M.D., Carr, M.J. (2008). Geochemical Evolution of Ngorongoro Caldera, Northern Tanzania: Implications for Crust-Magma Interaction. Earth and Planetary Science Letters, 271 (1–4): 337–47. DOI: https://doi.org/10.1016/j.epsl.2008.04.014
Mshiu, E.E., Gläßer, C., Borg, G. (2015). Identification of hydrothermal paleofluid pathways, the pathfinders in the exploration of mineral deposits: A case study from the sukumaland greenstone belt, Lake Victoria Gold Field, Tanzania. Advances in Space Research, 55(4): 1117–1133. DOI: https://doi.org/10.1016/j.asr.2014.11.024
Nabighian, M.N. (1972). The Analytic Signal of Two-Dimensional Magnetic Bodies with Polygonal Cross-Section: Its Properties and Use for Automated Anomaly Interpretation. Geophysics, 37 (3): 507–517. DOI: https://doi.org/10.1190/1.1440276
Nabighian, M.N. (1974). Additional Comments on the Analytic Signal of Two-Dimensional Magnetic Bodies with Polygonal Cross-Section. Geophysics, 39 (1): 85–92. DOI: https://doi.org/10.1190/1.1440416
Nzaro, M.A. (1970). Geothermal Resources of Tanzania. Geothermics, 2 (2): 1039–1043. DOI: https://doi.org/10.1016/0375-6505(70)90412-8
Pilkington, M. (2007). Locating geologic contacts with magnitude transforms of magnetic data. Journal of Applied Geophysics, 63 (2): 80–89. DOI: https://doi.org/10.1016/j.jappgeo.2007.06.001
Phillips, J.D. (1997). Potential-Field Geophysical Software for the PC, version 2.2. USGS, Open-File Report 97-725. DOI: https://doi.org/10.3133/ofr97725
Phillips, J.D., Hansen, R.O., Blakely, R.J. (2007). The use of curvature in potential-field interpretation. Exploration Geophysics, 38 (2): 111–119. DOI: https://doi.org/10.1071/EG07014
Pour, A. B., Hashim, M., Genderen, J. (2013). Detection of Hydrothermal Alteration Zones in a Tropical Region Using Satellite Remote Sensing Data: Bau Goldfield, Sarawak, Malaysia. Ore Geology Reviews, 54: 181–196. DOI: https://doi.org/10.1016/j.oregeorev.2013.03.010
Rosenberg, M. (2017). Volcanic and Tectonic Perspectives on the Age and Evolution of the Wairakei-Tauhara Geothermal System. PhD Thesis, Victoria University of Wellington, New Zealand, 258–263. DOI: http://hdl.handle.net/10063/6436
Rymer, H., Brown, G.C. (1986). Gravity Fields and the Interpretation of Volcanic Structures: Geological Discrimination and Temporal Evolution. Journal of Volcanology and Geothermal Research, 27 (3–4): 229–254. DOI: https://doi.org/10.1016/0377-0273(86)90015-6
Saadi, N.M., Watanabe, K. (2008). Lineaments extraction and analysis in Eljufra area, Libya. Journal of Applied Remote Sensing, 2 (1), 023538. DOI: https://doi.org/10.1117/1.2994727
Sabins, F. (1997). Remote Sensing Principles and Interpretation, 3rd ed.; W.H. Freeman & Co: New York, 494 pp.
Sandwell, D.T., Smith W.H.F. (2009). Global marine gravity from retracked Geosat and ERS-1 altimetry: Ridge Segmentation versus spreading rate. Journal of Geophysical Research: Solid Earth, 114 (B1): B01411. DOI: https://doi.org/10.1029/2008JB006008
Sandwell, D.T., Garcia, E., Soofi, K., Wessel, P., Smith, W.H.F. (2013). Toward 1-mGal Accuracy in Global Marine Gravity from CryoSat-2, Envisat, and Jason-1. The Leading Edge, 32 (8): 892–899. DOI: https://topex.ucsd.edu/sandwell/publications/144.pdf
Sandwell, D.T., Müller, R.D., Smith, W.H.F., Garcia, E., Francis, R. (2014). New global marine gravity model from CryoSat-2 and Jason-1 reveals buried tectonic structure. Science, 346 (6205): 65–67. DOI: https://doi.org/10.1126/science.1258213
Simiyu, S.M., Keller, G.R. (1997). An Integrated Analysis of Lithospheric Structure across the East African Plateau Based on Gravity Anomalies and Recent Seismic Studies. Tectonophysics, 278 (1–4): 291–313. DOI: https://doi.org/10.1016/S0040-1951(97)00109-1
Ulusoy, İ. (2016). Temporal Radiative Heat Flux Estimation and Alteration Mapping of Tendürek Volcano (Eastern Turkey) Using ASTER Imagery. Journal of Volcanology and Geothermal Research, 327: 40–54. DOI: https://doi.org/10.1016/j.jvolgeores.2016.06.027
Wilkinson, P., Mitchell, J.G., Cattermole, P.J., Downie, C. (1986). Volcanic Chronology of the Men-Kilimanjaro Region, Northern Tanzania. Journal of the Geological Society, 143 (4): 601–605. DOI: https://doi.org/10.1144/gsjgs.143.4.0601
This work is licensed under a Creative Commons Attribution 4.0 International License.
