Assessment of the Kiejo-Mbaka geothermal field by three-dimensional geophysical modelling

Rizzello, Daniele; Armadillo, Egidio; Pasqua, Claudio; Pisani, Paolo; Principe, Claudia; Lelli, Matteo; Didas, Makoye; Giordan, Valeria; Mnjokava, Taramaeli; Kabaka, Kato; Lucas, Tumbu; Marini, Luigi

doi:10.1007/s40948-022-00456-5

Cited by 4 publications

(4 citation statements)

References 69 publications

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“…We refer the reader to Chapter 6 in Chave & Jones (2012) for a detailed look at these complicating factors in interpreting MT field data and strategies for deployment. Furthermore, additional considerations should account for the cation exchange capacity (CEC) of clays that can play a crucial role in the electrical conduction of Water Resources Research 10.1029/2023WR035906 shales and shaly sands (Schön, 2015), using other formulations of Archies' law, like the one presented by Waxman and Smits (1968), as found in other studies (Armadillo et al, 2020;Rizzello et al, 2022).…”

Section: Discussionmentioning

confidence: 99%

Groundwater Circulation Within the Mountain Block: Combining Flow and Transport Models With Magnetotelluric Observations to Untangle Its Nested Nature

Gonzalez‐Duque,

Gomez‐Velez,

Person

et al. 2024

Water Resources Research

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Mountains are vital water sources for humans and ecosystems, continuously replenishing lowland aquifers through surface runoff and mountain recharge. Quantifying these fluxes and their relative importance is essential for sustainable water resource management. However, our mechanistic understanding of the flow and transport processes determining the connection between the mountain block and the basin aquifer remains limited. Traditional conceptualizations assume groundwater circulation within the mountain block is predominantly shallow. This view neglects the role of deep groundwater flowpaths significantly contributing to the water, solute, and energy budgets. Overcoming these limitations requires a holistic characterization of the multiscale nature of groundwater flow along the mountain‐to‐valley continuum. As a proof‐of‐concept, we use a coupled groundwater flow and transport model to design a series of numerical experiments that explore the role of geology, topography, and weathering rates in groundwater circulation and their resulting resistivity patterns. Our results show that accumulating solutes near stagnation zones create contrasting electrical resistivity patterns that separate local, intermediate, and regional flow cells, presenting a target for magnetotelluric observations. To demonstrate the sensitivity of magnetotelluric data to features in our resistivity models, we use the MARE2DEM electromagnetic modeling code to perform forward and inverse simulations. This study highlights the potential of magnetotelluric surveys to image the resistivity structure resulting from multiscale groundwater circulation through relatively impervious crystalline basement rocks in mountainous terrains. This capability could change our understanding of the critical zone, offering a holistic perspective that includes deep groundwater circulation and its role in conveying solutes and energy.

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Section: Discussionmentioning

confidence: 99%

Groundwater Circulation Within the Mountain Block: Combining Flow and Transport Models With Magnetotelluric Observations to Untangle Its Nested Nature

Gonzalez‐Duque,

Gomez‐Velez,

Person

et al. 2024

Water Resources Research

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“…In the upper levels of active geothermal systems (temperatures < 200 °C) where low salinity groundwaters or mixed groundwater-geothermal fluids are present, the lowtemperature, high-CEC smectite clays will dominate over the fluid salinity as the main pathway for conduction. At deeper levels in the systems where higher salinity fluids occur and lower CEC illites prevail, clay conductivity will be less of s fsctor [Ussher et al, 2000, Cumming, 2009Cumming and Mackie, 2010;Mũnoz, 2014;Armadillo et al, 2020, Rizzello et al, 2022. Figure 10.…”

Section: Relationships Between Alteration and Resistivitymentioning

confidence: 99%

“…values [Ussher et al, 2000;Cumming, 2009;Cumming and Mackie, 2010;Mũnoz, 2014;Armadillo et al, 2020, Rizzello et al, 2022. A common conceptual model for high-enthalpy geothermal systems with magma penetrating into shallower crustal levels is the presence of a high-conductivity subsurface layer beneath an increasing resistivity layer.…”

Section: Relationships With Temperature Distributionmentioning

confidence: 99%

“…In the discussion take into account that in some systems there is a clear electrical resistivity signature directly associated with fault systems. For instance, in the Chingshui geothermal field [Chang et al, 2014] [Rizzello et al, 2022] in southern Tanzania or at Alalobeda in northern Ethiopia [Rizzello et al, 2021], where faults are revealed in the resistivity MT models by vertical shifts of the bottom of the shallower conductive layers (usually associated with low temperature clay alterations) and eventually confirmed by the gravimetric signatures. In our study area resistance and temperature changes have been created in the study area due to faults.…”

Section: Faults In the Resistivity Sectionmentioning

confidence: 99%

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Focused and Smooth Inversion2D modelling of Magnetotelluric data from the Sabalan Geothermal Field in Northwestern Iran

Hasanalizadeh Kolagari,

Kalateh

2024

Annals of Geophysics

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Magnetotelluric measurements from the Sabalan geothermal field in northwestern Iran have provided clear indications of geothermal reservoirs. This study aimed to identify shallow and deeper conductivity anomalies associated with geothermal systems in the Sabalan area. The magnetotelluric method is widely used for exploring subsurface resources, as it is suitable for detecting subsurface anomalies at significant depths. Based on modeling results, thick conductive layer was found near the surface of the Moil Valley area, where two reservoirs are embedded. The main reservoir, located on the west side of Sabalan volcano, extends from the south and southwest of Sabalan peak to the west and Moil valley. The dimensions of this reservoir are almost twice as large as the estimated volume obtained from previous studies. Another smaller reservoir is located to the north of the peak.

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New MT surveys and 3D resistivity imaging beneath the Ngozi-Rungwe volcanoes at the triple rift junction of the East African Rift System in SW Tanzania: Support for integrated interpretations of geothermal conceptual models

Didas,

Armadillo,

Hersir

et al. 2024

Geothermics

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Assessment of the Kiejo-Mbaka geothermal field by three-dimensional geophysical modelling

Cited by 4 publications

References 69 publications

Groundwater Circulation Within the Mountain Block: Combining Flow and Transport Models With Magnetotelluric Observations to Untangle Its Nested Nature

Groundwater Circulation Within the Mountain Block: Combining Flow and Transport Models With Magnetotelluric Observations to Untangle Its Nested Nature

Focused and Smooth Inversion2D modelling of Magnetotelluric data from the Sabalan Geothermal Field in Northwestern Iran

New MT surveys and 3D resistivity imaging beneath the Ngozi-Rungwe volcanoes at the triple rift junction of the East African Rift System in SW Tanzania: Support for integrated interpretations of geothermal conceptual models

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