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Magmatic evolution and crustal accretion of the northern Oman-United Arab Emirates ophiolite

Lilly, Richard Mark. 2006. Magmatic evolution and crustal accretion of the northern Oman-United Arab Emirates ophiolite. PhD Thesis, Cardiff University.

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Abstract

The Magmatic Evolution and Crustal Accretion of the northern Oman-U.A.E. ophiolite The Oman-United Arab Emirates (U. A.E.) ophiolite is the largest and best-preserved ophiolite complex in the world and has assumed critical importance in guiding ideas as to the functioning of mid-ocean ridge magma chambers and accretion of lower crust formed at a fast-spreading ridge. The portion of the ophiolite within the United Arab Emirates has received much less study than that within the Sultanate of Oman, particularly with regard to its magmatic evolution. Fieldwork has been conducted in co-operation with the British Geological Survey on the ophiolite sections in the U.A.E. Geochemical and field characteristics of these plutonic and extrusive units provide important constraints on the influence subduction-related fluids have on crustal accretion processes. Initial VI magmatic events exhibit a MORB-like composition and record mid-ocean ridge accretion processes which relate to modern crust, forming from steady-state magma chambers. The Khawr Fakkan Block provides the first 'true' MORB mantle source signature to be documented in the Oman-U.A.E. ophiolite, which represents pre-subduction zone influenced oceanic crust and applies constraints to the mechanisms and timing of subduction initiation and propagation. These primary events were followed by V2 magmatic events in a supra subduction zone (SSZ) setting, with plutonic magmatism localised predominantly along major faults. Each subsequent magmatic event exhibits an increase in the subduction related component to the mantle source. The V2, SSZ, magmatic period of the northern Oman-U.A.E. ophiolite can be regarded as an embryonic volcanic arc, which ceased magmatism and was obducted before reaching maturity. The northern Oman-U.A.E. ophiolite records the transition from spreading- to subduction-related volcanism in a SSZ setting within a marginal (fore-arc) basin, representing the change from steady-state to plutonic magmatism. The SSZ signature increases to the north spatially and temporally.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Earth and Ocean Sciences
Subjects: Q Science > QE Geology
ISBN: 9781303204692
Date of First Compliant Deposit: 30 March 2016
Last Modified: 12 Feb 2016 23:15
URI: http://orca.cardiff.ac.uk/id/eprint/56058

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