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Title: The magnetic evolution of Dabbahu Volcano and the 2010 eruption of Erta Ale, Afar, Ethiopia
Author: Field, Lorraine Patricia
ISNI:       0000 0004 2713 0630
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2011
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The development of magmatism during the transition from continental rifting to sea-floor spreading remains poorly understood as most rifted margins are now inactive and buried beneath thick sediments. Dabbahu and the basaltic Erta Ale volcanoes situated within the actively rifting Afar region of northern Ethiopia, offer a unique opportunity to address this problem. The nature of rhyolitic volcanism, the sub-volcanic system, and their relationship to basaltic magmas involved in dyking events is investigated at Dabbahu volcano and forms the main subject of this study. The evolution of the volcano is constrained through 9 new 40Ar/39Ar dates and geochemical analysis of 93 samples, supplemented by a new geological map. Dabbahu has been active for over 65,000 years, erupting basalts through to evolved pantellerites. Modelling shows the evolved magmas were derived through protracted (>80%) fractional crystallisation. A shallow magma storage region (1-5 km) is confirmed through melt inclusion analysis, and further constrained with seismic and InSAR data. However, it is proposed that this region is a temporary site of pre-eruptive storage for evolved products and the site of differentiation lies at depth within the crust (14-20 km). Field evidence indicates that magmas were not erupted in fractionation sequence and mixing between cogenetic magmas is recorded on all scales. The input of new magma may have been a key eruption trigger at Dabbahu throughout its history, as was the case in the most recent 2005 eruption at the Da’Ure vent following dyke injection. Erta Ale is a basaltic shield within the most northerly magmatic segment of the same name, and contains one of the world’s longest lived lava lakes. An overview of the events of the November 2010 eruption in this remote area has been constructed through a combination of ground observation and remote sensing. Analysis of zero age lavas provides new insights into this unique volcano
Supervisor: Blundy, Jon Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available