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Dating the geologic history of Oman's Semail ophiolite: insights from U-Pb geochronology

Warren, C; Parrish, Randall R; Waters, D; Searle, MP. 2005 Dating the geologic history of Oman's Semail ophiolite: insights from U-Pb geochronology. Contributions to Mineralogy and Petrology, 150 (4). 403-422. 10.1007/s00410-005-0028-

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Abstract/Summary

Eclogites from the deepest structural levels beneath the Semail ophiolite, Oman, record the subduction and later exhumation of the Arabian continental margin. Published ages for this high pressure event reveal large discrepancies between the crystallisation ages of certain eclogite-facies minerals and apparent cooling ages of micas. We present precise U-Pb zircon (78.95 ± 0.13 Ma) and rutile (79.6 ± 1.1 Ma) ages for the eclogites, as well as new U-Pb zircon ages for trondhjemites from the Semail ophiolite (95.3 ± 0.2 Ma) and amphibolites from the metamorphic sole (94.48 ± 0.23 Ma). The new eclogite ages reinforce published U-Pb zircon and Rb-Sr mineral-whole rock isochron ages, yet are inconsistent with published interpretations of older 40Ar/39Ar phengite and Sm-Nd garnet dates. We show that the available U-Pb and Rb-Sr ages, which are in tight agreement, fit better with the available geological evidence, and suggest that peak metamorphism of the continental margin occurred during the later stages of ophiolite emplacement.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1007/s00410-005-0028-
Programmes: BGS Programmes 2008 > NERC Isotope Geoscience Laboratory
ISSN: 0010-7999
Additional Keywords: Oman, Semail ophiolite, U-Pb geochronology
NORA Subject Terms: Earth Sciences
Date made live: 28 Jul 2009 15:22
URI: http://nora.nerc.ac.uk/id/eprint/7848

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