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21 results on '"Getaneh, Worash"'

12. Stratigraphy and eruptive history of Gedemsa caldera volcano, Central Main Ethiopian Rift

Author

Bedassa, Gemechu, Ayalew, Dereje, Getaneh, Worash, Fontijn, Karen, Emishaw, Luelseged, Melaku, Abate A., Tadesse, Amdemichael, Demissie, Zelalem, Swindle, Andrew, Chamberlain, Katy J., Bedassa, Gemechu, Ayalew, Dereje, Getaneh, Worash, Fontijn, Karen, Emishaw, Luelseged, Melaku, Abate A., Tadesse, Amdemichael, Demissie, Zelalem, Swindle, Andrew, and Chamberlain, Katy J.

Abstract

Gedemsa caldera is a peralkaline volcanic depression located in the Central sector of the Main Ethiopian Rift. An integrated volcanological study of stratigraphic sections was carried out in order to constrain the eruptive history of Gedemsa caldera volcano (GCV), Ethiopia. Textural analyses on plagioclase crystals together with field observations shed light on magma chamber processes feeding the volcanic complex. A multi-vent eruption is ascribed to the pre-caldera volcanic products, as can be seen from the varying caldera wall sequences comprising lavas and pyroclastic deposits. At least three major caldera-forming eruptions are identified producing: 1) a lower ignimbrite, 2) extensive pumice fall and pyroclastic density current deposits, and 3) an upper ignimbrite exposed in different areas of the caldera, indicating a sector collapse. We identified 20 individual pyroclastic deposits found outside and within the caldera that erupted after the climactic caldera collapse. The most recent volcanic activity at Gedemsa is characterized by rhyolitic lava domes and pyroclastic deposits from eruptions through numerous vents aligned with WNW-ESE pre-existing cross-cutting structures. Macrocryst disequilibrium textures such as fine-scale oscillatory zoning (FOZ), sieve textures, glomerocryst, and synneusis indicate that magma reservoir is characterized by repeated magma injection, convection flows, and mixing., SCOPUS: ar.j, info:eu-repo/semantics/published

Published
2023

13. The influence of parent rock, mining and processing technologies on the industrial quality of kaolin concentrate –case study from Bombowha kaolin, Ethiopia

Author

W/Mariam , Tilahun and Getaneh, Worash

Subjects
Ethiopia, Kaolin Concentrate, Mining, Wet Processing
Abstract

Bombowha kaolin deposit is a primary deposit formed mainly through weathering of granite and pegmatite. This research was designed to evaluate the influence of parent material, mining practices and processing technology on the quality of processed kaolin. Geochemical, mineralogical, and technological properties of kaolin were analyzed and field observations conducted to evaluate the influence. Samples of the parent rocks, kaolin deposit, Run-Of-Mine, and processed kaolin were analyzed for their geochemistry, mineralogy and physical properties. Results show that the kaolin derived from pegmatite has better quality (high alumina, low silica, better plasticity, low coloring elements and others) than the granite-derived one. The poor quality of the granite-derived kaolin is ascribed to its incomplete kaolinization as evidenced by the presence of minor halloysite. The geochemical analysis of the Run-Of-Mine shows close similarity to that of the parent granite demonstrating severe dilution during mining, hauling and storage of kaolin ore. The high pit-wall angle (80-85°), the rheologically weak overburden, old excavation machinery and unsystematic delineation of mineable portion of the deposit contributed to high level of dilution. The properties of processed kaolin show the wet processing method brought substantial improvement in the quality of the kaolin (Al2O3 increased by nearly 98% and SiO2 decreased by 36% with respect to the Run-Of-Mine). Had the feed kaolin ore not been diluted, the kaolin concentrate would have been better than what is achieved through the adopted processing method. Systematic mine design, selective mining, and graded stockpiling of kaolin ore are advised for better quality kaolin concentrate.

Published
2022
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21. Evaluation of a Smectite Adsorption-Based Electrostatic System to Decontaminate F − Rich Thermal Waters.

Author

Fanari, Fabio, Lodi, Matteo Bruno, Getaneh, Worash, Fanti, Alessandro, Desogus, Francesco, and Valera, Paolo

Subjects
GEOTHERMAL resources, SMECTITE, ELECTROMAGNETIC fields, WATER springs, MONTMORILLONITE, CONSUMPTION (Economics), FLUORIDES
Abstract

Several studies have shown the presence of fluoride levels much higher than the 1.5 mg/L threshold concentration recommended by WHO in the spring waters and wells of the Ethiopian Rift Valley. Available defluoridation techniques can be costly, present complicated technical aspects, and show limited effectiveness. Therefore, it is necessary to devise innovative, sustainable, and effective solutions. This study proposes an alternative method of intervention to the known techniques for removing fluoride from water, particularly suitable for smaller rural communities. In particular, in this work, the possibility to use electromagnetic fields as a physical method for removing the excess fluoride was investigated. The study was carried out by developing a multiphysics model used for studying and envisaging the design of a device. In this framework, the combination of this approach with the use of highly reactive smectite clay was numerically studied. The results obtained, although preliminary, indicate that the proposed system could significantly impoverish the waters of the Rift Valley from fluoride, with the consequence of obtaining a resource suitable for human consumption, in particular for rural communities. However, further theoretical investigations and experimental phases will be necessary to achieve the desired results. [ABSTRACT FROM AUTHOR]

Published
2022
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