Three-dimensional hydrostratigraphical modelling supporting the evaluation of fluoride enrichment in groundwater: Lakes basin (Central Ethiopia)

Ghiglieri, Giorgio; Pistis, Marco; Bekele, Afework; Azagegn, Tilahun; Engidasew, Tesfaye Asresahagne; Pittalis, Daniele; Soler, Albert; Barbieri, Manuela; Navarro-Ciurana, Dídac; Carrey, Raúl; Puig, Roser; Carletti, Alberto; Balia, Roberto; Haile, Tigistu

doi:10.1016/j.ejrh.2020.100756

Cited by 12 publications

(3 citation statements)

References 23 publications

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“…S7). In agreement with the conceptual hydrogeological model of the area by (Ghiglieri et al, 2020) C1 can be interpreted as a fully saturated aquifer system within pyroclastics (ignimbrites) and basalts, where water from the rift shoulders flows into the rift valley.…”

Section: Doisupporting

confidence: 79%

“…In agreement with the conceptual hydrogeological model of the study area by Ghiglieri et al (2020), the conductor C1 images a shallow layer of pyroclastics and lavas that has been classified as a fissured aquifer. Considering reported groundwater electrical conductivities in the area , the most widely distributed observed bulk conductivities within C1 (σ = 0.1 − 0.2 S/m) would require an unreasonably large fluid fraction within C1 (see SI: Text S6.2).…”

Section: C1: Aquifer/sediment Unitsupporting

confidence: 78%

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The interplay of rifting, magmatism and formation of geothermal resources in the Ethiopian Rift constrained by 3-D magnetotelluric imaging

Dambly

Samrock

Grayver

et al. 2022

Preprint

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The Main Ethiopian Rift (MER) is accompanied by extensive volcanism and the formation of geothermal systems, both having an imminent impact on lives of millions of local inhabitants. Although previous studies from the region found evidence that asthenospheric upwelling and associated decompression melting provide melt to magmatic mush systems that feed the tectonovolcanic segments in the rift valley, no geophysical model imaged these regional and local scale transcrustal structures within a single comprehensive 3-D model. To fill this gap, we combined regional and local magnetotelluric data sets to obtain the first multi-scale 3-D electrical conductivity model of the central MER. The model clearly images a magma ponding zone with up to 7 vol.% melt at the base of the crust in the western part of the rift, its connection to Aluto volcano via a tectonically controlled transcrustal magmatic mush system and how the melt, stored at shallow crustal depths, supplies heat for Aluto's geothermal system. Our model provides evidence that different volcano-tectonic lineaments in the rift valley share a common melt source, which has been debated in the past. The presented multi-scale model provides new constraints as well as geologic insights into the melt distribution below the rift and will facilitate future geothermal developments and volcanic hazard assessments in the MER.

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Section: Doisupporting

confidence: 79%

Section: C1: Aquifer/sediment Unitsupporting

confidence: 78%

The interplay of rifting, magmatism and formation of geothermal resources in the Ethiopian Rift constrained by 3-D magnetotelluric imaging

Dambly

Samrock

Grayver

et al. 2022

Preprint

View full text Add to dashboard Cite

show abstract

“…Following the conceptual hydrogeological model of the study area (Ghiglieri et al., 2020), the conductor C1 images a shallow layer of pyroclastics and lavas that has been classified as a fissured aquifer. Considering reported groundwater electrical conductivities with a mean of 0.3 S/m in the area (Burnside et al., 2021), the most widely distributed observed bulk conductivities within C1 ( σ = 0.1–0.2 S/m) would require an unreasonably large fluid fraction within C1 (see Text S6.2 in Supporting Information S1).…”

Section: Resultsmentioning

confidence: 99%

Insights on the Interplay of Rifting, Transcrustal Magmatism and Formation of Geothermal Resources in the Central Segment of the Ethiopian Rift Revealed by 3‐D Magnetotelluric Imaging

et al. 2023

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The East African Rift system (EARS) is a prominent continental rift that shaped the landscape of East Africa, including the East African Plateau, rift valleys and numerous volcanoes. Rifting and rift-related volcanism in East Africa played a role in early human evolution (King & Bailey, 2006) and to this date affect the life of humans due to volcanic hazards (Biggs et al., 2021), but also by providing rift-associated natural resources, including geothermal energy resources (Benti et al., 2023;Burnside et al., 2021). A large number of studies, especially in the northern part of the EARS, which includes the Main Ethiopian Rift (MER), have provided a wealth of information Abstract The Main Ethiopian Rift is accompanied by extensive volcanism and the formation of geothermal systems, both having a direct impact on the lives of millions of inhabitants. Although previous studies in the region found evidence that asthenospheric upwelling and associated decompression melting provide melt to magmatic systems that feed the tectono-magmatic segments in the rift valley, there is a lack of geophysical models imaging these regional and local scale transcrustal structures. To address this challenge, we use the magnetotelluric method and image subsurface electrical conductivity to examine the magmatic roots of Aluto volcano, quantify and interpret the melt distribution in the crust considering established concepts of continental rifting processes and constrain the formed geothermal system. Specifically, we combined regional (maximum 30 × 120 km 2 ) and local (15 × 15 km 2 ) magnetotelluric data sets and obtained the first multi-scale 3-D electrical conductivity model of a segment of the central Main Ethiopian Rift. The model unravels a magma ponding zone with up to 7 vol. % melt at the base of the crust (30-35 km b.s.l.) in the western part of the rift and its connection to Aluto volcano via a fault-aligned transcrustal magma system. Melt accumulates at shallow crustal depths (≥4 km b.s.l.), thereby providing heat for Aluto's geothermal system. Our model suggests that different volcano-tectonic lineaments in the rift valley share a common melt source. The presented model provides new constraints on the melt distribution below a segment of the rift which is important for future geothermal developments and volcanic hazard assessments in the region.Plain Language Summary Continental rifting is a fundamental process of plate tectonics that breaks continents apart to ultimately form new oceans. The landscape of the Main Ethiopian Rift is characterized by abundant volcanism and hot springs, which indicate the presence of geothermal resources formed by magmatic heating of subsurface fluids. Here we present a new 3-D subsurface electrical conductivity image of the magmatic system and geothermal reservoir beneath the Aluto volcano in the Main Ethiopian Rift. The model allows us to estimate the amount and distribution of magmatic melt. This is the first model that provides a high-resolution image of the entire magmatic system below a centr...

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Fluoride Contamination in Groundwater—A Review

Chaudhuri,

Sahoo,

Debsarkar

et al. 2024

Environmental Science and Engineering

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Three-dimensional hydrostratigraphical modelling supporting the evaluation of fluoride enrichment in groundwater: Lakes basin (Central Ethiopia)

Cited by 12 publications

References 23 publications

The interplay of rifting, magmatism and formation of geothermal resources in the Ethiopian Rift constrained by 3-D magnetotelluric imaging

The interplay of rifting, magmatism and formation of geothermal resources in the Ethiopian Rift constrained by 3-D magnetotelluric imaging

Insights on the Interplay of Rifting, Transcrustal Magmatism and Formation of Geothermal Resources in the Central Segment of the Ethiopian Rift Revealed by 3‐D Magnetotelluric Imaging

Fluoride Contamination in Groundwater—A Review

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