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Title: Plumes, plums and the fate of oceanic plates
Author: Prytulak, Julie
ISNI:       0000 0004 2736 8569
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2008
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This thesis investigates processes controlling melting beneath ocean islands. Specifically, the physical nature and resulting melting behaviour of the mantle source is addressed by novel approaches. This thesis ranges in scope from broad global perspectives (Chapter 2) to specific investigation of single volcanic edifices (Chapter 4, 5). In particular, I use the moderately incompatible major element titanium (chapter 2) and U-series isotopes (chapter 3, 4, 5) to address mantle melting. Examination of global OIB Ti concentrations, reveals that the source region of most OIB require addition of ~ 1 0% or less recycled mafic oceanic crust. Analytical methods for U-series measurement have been refined (Chapter 3). Detailed examination of one OIB locality (Pico, Azores, Chapter 4) reveals that recycled crust cannot directly contribute to the lavas. Instead, recycled crust must be 'distilled' through the overlying mantle by interaction of eclogitic melts with the surrounding peridotite. At the eventual onset of peridotitic melting, the source carries an enriched signature reflecting mafic crustal addition, but no record of its disparate melting behaviour. Finally, investigation of Sao Miguel, Azores enforces the notion that recycled lithologies do not exert major control on source melting behaviour. This is illustrated by the lack of correlation between the wide range of long-lived isotopic compositions and U-series isotopes. Indeed, the greatest range of suggested primary U-series signatures on Sao Miguel occurs in lavas with the same long-lived isotopic composition.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available