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| Titel |
Morphometric and magmatic evolution at the Boset-Bericha Volcanic Complex in the Main Ethiopian Rift |
| VerfasserIn |
Melanie Siegburg, Thomas Gernon, Jonathan Bull, Derek Keir, Rex Taylor, Casey Nixon, Bekele Abebe, Atalay Ayele |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250138173
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| Publikation (Nr.) |
 EGU/EGU2017-1109.pdf |
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| Zusammenfassung |
| Tectono-magmatic interactions are an intrinsic feature of continental rifting and break up in
the Main Ethiopian Rift (MER). The Boset-Bericha volcanic complex (BBVC) is one of the
largest stratovolcanoes in the MER (with a total area of ∼870 km2), with volcanism largely
occurring over the last ∼2 Myr. Despite the fact that 4 million people live within 100 km of
the volcano, little is known about its eruptive history and how the volcanic system interacts
with rift valley tectonics. Here, we present a detailed relative eruption chronology combined
with morphometric analyses of different elements of the volcanic complex and
petrological analyses to constrain morphometric and magmatic evolution at the BBVC.
Additionally, tectonic activity has been characterised around the BBVC, all based on
field observations and mapping using high-resolution digital elevation data. The
BBVC consists of the Gudda Volcano and the younger Bericha Volcano, two silicic
eruption centres located along the NNE-SSW trending rift axis. The fault population
predominantly comprises distributed extensional faults parallel to the rift axis, as well as
localised discrete faults with displacements of up to 50 m in the rift centre, and up to
200 m in the NE-SW trending border fault system. Multiple cones, craters and
fissure systems are also oriented parallel to the rift axis, i.e. perpendicular to the
minimum compressive stress. The eruption history of BBVC can be differentiated into 5
main eruption stages, subdivided into at least 12 eruptive phases with a total of 128
mappable lava flows. Crosscutting relationships of lava flows provide a relative
chronology of the eruptive history of the BBVC, starting with pre-BBVC rift floor
basalts, pre-caldera and caldera activity, three post-caldera phases at the Gudda
Volcano and two phases forming the Bericha Volcano. At least four fissure eruption
phases occurred along the rift axis temporally in between the main eruptive phases.
Morphometric analyses indicate a total corrected volume of eruptive material at the
BBVC of ∼36 km3. The magmatic and morphometric evolution of the BBVC is
spatially and temporally complex, showing a bimodal distribution of effusive basalts
towards explosive peralkaline trachytic and rhyolitic lavas for the Gudda and Bericha
Volcano, respectively, with rare intermediate lavas from fissure eruptions. Preliminary
geochemical data suggest that fractional crystallisation may have played an important role
in driving magmatic evolution the BBVC. This study emphasises the important
role of tectono-magmatic interactions in the evolution of a continental rift system. |
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