Characterization of the Heat Source of Butajira Geothermal Field Ethiopia: Noble Gas Approach
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Date
2019-05-05
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Addis Ababa University
Abstract
Butajira geothermal prospect is found in the Central Main Ethiopian Rift (CMER) near the western escarpment where thermal manifestations such as hot springs are aligned along NNE/SSW direction with surface temperature reaching up to 86◦c are located. Hydrothermal alteration materials in the area, the chemistry of the fluids, the source of heat that drives the geothermal system as well as the sub surface reservoir temperature is not well defined. The main objective of this study is to provide constraints on the heat source and to estimate the reservoir temperature using volatile elements like helium as well as to estimate reservoir temperature using cation geothermometers. As a result sub surface temperature exceeding 150◦c is obtained using Na-K geothermometer and the measured ratio of 3He/4He shows broadly consistent value of 2.3Ra indicating 12% of plume signature and 88% of crustal origin referring to a very high crustal contamination probably derived from well evolved stagnant magma chamber at relatively shallow depth.
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Keywords
Characterization, Heat Source, Butajira Geothermal Field, Ethiopia, Noble Gas Approach