Changing volatile emissions and sources along the Ethiopian Rift
Changing volatile emissions and sources along the Ethiopian Rift
Rift volcanoes are sites of intense volatile emissions. However, major uncertainties remain about the magnitude of rift volatile fluxes, particularly for greenhouse gases (e.g. CO
2) and whether along-rift variations in degassing relate to changing mantle sources and/or rifting processes (i.e. melt production and lithospheric thinning). Here, we investigate CO
2 flux and gas isotopes in Ethiopia; a mature, plume-influenced continental rift. We focus on one of the largest caldera volcanoes, Bora-Baricha-Tulu Moye (BBTM), which is situated in a region of high mantle melt production in the Central Main Ethiopian rift (∼500 km south-west the putative plume head). BBTM gases are characterized by plume-like
3He/
4He values up to 17 R
a (the highest ever observed in Ethiopian Rift fumaroles) and we calculate total magmatic CO
2 flux of 757–901 t d
-1 (making BBTM the largest volcanic CO
2 emitter in the Ethiopian Rift). Using our CO
2 flux measurements, we estimate total CO
2 emissions from Ethiopia’s volcanic systems to be 2500–9200 kt yr
-1 and reveal important along-rift variation in CO
2 flux. High CO
2 flux sectors are found in Central Afar, as well as the Northern and Central Main Ethiopian Rift. These sectors are all regions of high partial melt content (evidenced by low seismic velocity in the underlying mantle) and also show the greatest
3He/
4He values (>14 R
a). Cooccurrence of high mantle melt production, elevated CO
2 emissions and high
3He/
4He demonstrates that in mature continental rifts carbon emissions and plume volatile contributions are particularly elevated in regions of greatest lithospheric thinning and mantle melting.
CO emissions, Ethiopia, He isotopes, Magmatism, Mantle plume, Rift
Melaku, Abate A.
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Teferi, Gemechu
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Mihretie, Takele
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Guðbrandsson, Snorri
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Sinetebeb, Yared
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Ballentine, Chris J.
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Keir, Derek
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Chambers, Emma L.
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Hutchison, William
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15 February 2026
Melaku, Abate A.
e4442c09-7fff-45bd-9dd3-e58137a997c6
Teferi, Gemechu
83c30900-af1b-4a55-bbb7-804e0aaf2f1d
Mihretie, Takele
bb23a5e9-69d3-4b45-a633-17c9429cebce
Guðbrandsson, Snorri
2cfbb8cf-3896-4efc-bdd1-06eec521fbc0
Sinetebeb, Yared
eb53fd41-eb9d-4bf8-a85a-eb4049cfe73e
Ballentine, Chris J.
e5971e2e-9caa-41b7-9071-c5e2c82b4bd7
Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65
Chambers, Emma L.
4226fbb2-4651-4be8-af34-030930bc52d2
Hutchison, William
9c4883ca-24e2-4562-b18a-298475948534
Melaku, Abate A., Teferi, Gemechu, Mihretie, Takele, Guðbrandsson, Snorri, Sinetebeb, Yared, Barry, Peter H., Fischer, Tobias P., Balci, Ugur, Halldórsson, Sæmundur A., Ballentine, Chris J., Hillegonds, Darren J., Keir, Derek, Chambers, Emma L., Stuart, Finlay M. and Hutchison, William
(2026)
Changing volatile emissions and sources along the Ethiopian Rift.
Earth and Planetary Science Letters, 676, [119782].
(doi:10.1016/j.epsl.2025.119782).
Abstract
Rift volcanoes are sites of intense volatile emissions. However, major uncertainties remain about the magnitude of rift volatile fluxes, particularly for greenhouse gases (e.g. CO
2) and whether along-rift variations in degassing relate to changing mantle sources and/or rifting processes (i.e. melt production and lithospheric thinning). Here, we investigate CO
2 flux and gas isotopes in Ethiopia; a mature, plume-influenced continental rift. We focus on one of the largest caldera volcanoes, Bora-Baricha-Tulu Moye (BBTM), which is situated in a region of high mantle melt production in the Central Main Ethiopian rift (∼500 km south-west the putative plume head). BBTM gases are characterized by plume-like
3He/
4He values up to 17 R
a (the highest ever observed in Ethiopian Rift fumaroles) and we calculate total magmatic CO
2 flux of 757–901 t d
-1 (making BBTM the largest volcanic CO
2 emitter in the Ethiopian Rift). Using our CO
2 flux measurements, we estimate total CO
2 emissions from Ethiopia’s volcanic systems to be 2500–9200 kt yr
-1 and reveal important along-rift variation in CO
2 flux. High CO
2 flux sectors are found in Central Afar, as well as the Northern and Central Main Ethiopian Rift. These sectors are all regions of high partial melt content (evidenced by low seismic velocity in the underlying mantle) and also show the greatest
3He/
4He values (>14 R
a). Cooccurrence of high mantle melt production, elevated CO
2 emissions and high
3He/
4He demonstrates that in mature continental rifts carbon emissions and plume volatile contributions are particularly elevated in regions of greatest lithospheric thinning and mantle melting.
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Accepted/In Press date: 7 December 2025
e-pub ahead of print date: 18 December 2025
Published date: 15 February 2026
Keywords:
CO emissions, Ethiopia, He isotopes, Magmatism, Mantle plume, Rift
Identifiers
Local EPrints ID: 508980
URI: http://eprints.soton.ac.uk/id/eprint/508980
ISSN: 0012-821X
PURE UUID: ef4289e2-0309-43f1-99a9-0db3e6815a42
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Date deposited: 09 Feb 2026 17:46
Last modified: 10 Feb 2026 02:50
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Contributors
Author:
Abate A. Melaku
Author:
Gemechu Teferi
Author:
Takele Mihretie
Author:
Snorri Guðbrandsson
Author:
Yared Sinetebeb
Author:
Peter H. Barry
Author:
Tobias P. Fischer
Author:
Ugur Balci
Author:
Sæmundur A. Halldórsson
Author:
Chris J. Ballentine
Author:
Darren J. Hillegonds
Author:
Emma L. Chambers
Author:
Finlay M. Stuart
Author:
William Hutchison
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