Subsurface structural control of geothermal resources in a magmatic rift: gravity and magnetic study of the Tulu Moye geothermal prospect, Main Ethiopian Rift

Frontiers in Earth Science

Earth Science

Giacomo Corti¹  Zelalem Demissie²  Kevin Mickus³  Esubalew Yehualaw⁴  Abera Alemu⁵  Ameha A. Muluneh⁶  Wubamlak Nigussie⁷  Yoseph Muhabaw⁸  Derek Keir⁹ 

[1] Consiglio Nazionale Delle Ricerche, Istituto di Geoscienze e Georisorse, Firenze, Italy;Department of Geology, Wichita State University, Wichita, KS, United States;Department of Geosciences, Missouri State University, Springfield, MA, United States;Department of Geothermal Energy, Ministry of Mine and Energy, Addis Ababa, Ethiopia;School of Earth Sciences, Addis Ababa University, Addis Ababa, Ethiopia;School of Earth Sciences, Addis Ababa University, Addis Ababa, Ethiopia;Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Potsdam, Germany;School of Earth Sciences, Bahir Dar University, Bahir Dar, Ethiopia;School of Earth Sciences, Bahir Dar University, Bahir Dar, Ethiopia;Department of Earth and Environmental Sciences, University of Rochester, Rochester, NY, United States;School of Ocean and Earth Science, University of Southampton, Southampton, United Kingdom;Dipartimento di Scienze Della Terra, Università Degli Studi di Firenze, Florence, Italy;

关键词: East African Rift;    gravity/magnetic anomalies;    geothermal resources;    subsurface structure;    Tulu Moye geothermal prospect;   

DOI  :  10.3389/feart.2023.1181533

 received in 2023-03-07, accepted in 2023-07-13,  发布年份 2023

来源: Frontiers

【 摘 要 】

Since the Quaternary, extension and magmatism in the Main Ethiopian Rift (MER) have been mainly focused into narrow magmatic segments that have numerous volcanic centers and caldera collapses that offer favorable conditions for the occurrence of geothermal resources. However, the subsurface structure of the volcanic systems (0–10 km) and their link to the distribution of shallow geothermal resources remain unclear. To investigate the role of subsurface structures on the occurrence of these resources, we conducted gravity and magnetic studies combined with geological constraints within the Tulu Moye Geothermal Prospect (TMGP), one of the current geothermal prospects in the central MER associated with caldera collapses. Gravity data from the Global Gravity Model plus (GGMplus 2013) and ground magnetic data transformed into residual and derivative maps reveal that shallow magmatic intrusions occur under the volcanic centers (Tulu Moye, Bora, and Bericha). Our interpretation along with recent magnetotelluric model suggests that only the intrusion beneath Tulu Moye is currently magmatically active and includes partial melt, consistent with it being a primary heat source for the geothermal system. A new caldera formation model is proposed where the TMGP hosts an older large caldera (about 25 km diameter) within which there are several smaller nested caldera systems associated with the Bora, Bericha, and Tulu Moye volcanoes. Along with existing geologic, seismic, and magnetotelluric studies, our gravity and magnetic analysis indicate the interaction between NNE-SSW (rift-parallel) and NW-SE (cross-rift) trending faults, along with shallow magmatic intrusions and caldera systems, suggesting that such a large geothermal system is possible under these conditions.

【 授权许可】

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Copyright © 2023 Nigussie, Alemu, Mickus, Keir, Demissie, Muhabaw, Muluneh, Corti and Yehualaw.