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Reply to: Comment by Gray, Gregory and Miller on “Structural evolution, metamorphism and restoration of the Arabian continental margin, Saih Hatat region, Oman Mountains”

Searle, MP; Warren, CJ; Waters, DJ; Parrish, Randall R. 2005 Reply to: Comment by Gray, Gregory and Miller on “Structural evolution, metamorphism and restoration of the Arabian continental margin, Saih Hatat region, Oman Mountains”. Journal of Structural Geology, 27 (2). 375-377. 10.1016/j.jsg.2004.07.003

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Abstract/Summary

We welcome discussion of the complex structural interpretation of the HP zone of the Saih Hatat region, Oman. There are two very different models to explain the structures and timing of high-pressure metamorphism in NE Oman. Most geologists working in Oman favour a single, continuous NE-directed subduction to explain the origin and emplacement of the ophiolite and late-stage subduction of the continental margin to form high-pressure eclogite facies metamorphism (full references in Searle et al., 1994, Searle et al., 2003, Searle et al., 2004 and Searle and Cox, 2002). The second model favoured by Gregory et al., 1998, Gray et al., 2000 D.R. Gray, R.T. Gregory and J.M. Miller, A new structural profile along the Muscat–Ibra transect, Oman: implications for emplacement of the Semail ophiolite, Geological Society of America Special Paper 349 (2000), pp. 513–523. Full Text via CrossRefGray et al., 2000, Gray et al., 2004, Gray and Gregory, 2000 and Gray and Gregory, 2003 involves an early (130–95 Ma) nascent SW-dipping subduction zone dipping beneath the passive margin, followed by a flip to NE-directed subduction during ophiolite emplacement. The crux of the arguments centre around the structures in NE Saih Hatat and older (pre-95 Ma) 40Ar/39Ar and Sm/Nd ages from the As Sifah eclogites. At the outset, it is clearly wrong for Gray et al. to claim first recognition of the Saih Hatat fold-nappe. These structures were known for at least 15 years prior to 1998, by numerous geologists working in Oman, and were actually first mapped out at 1:100,000 scale by the BRGM group (map sheets Masqat, Quriat, Fanjah; Le Métour, 1986 and Le Métour et al., 1990). Searle et al. (1994, fig. 5) published photos of some of these structures, although our mapping at that stage was far from complete. The mapping by Miller et al. (2002), while similar to earlier mappings, represents a significant improvement. Although we do disagree in some respects with the mapping of Miller et al. (2002), the mapping was not the point of our disagreement with Gray and his colleagues. We do disagree strongly over two main issues: (1) the interpretation of the structures with respect to early nascent SW-dipping subduction beneath the Oman passive margin, and (2) the timing of HP metamorphism.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1016/j.jsg.2004.07.003
Programmes: BGS Programmes 2008 > NERC Isotope Geoscience Laboratory
ISSN: 0191-8141
Additional Keywords: Ophiolite, Obduction, Subduction, Eclogite, Oman, Restored cross-section
NORA Subject Terms: Earth Sciences
Related URLs:
Date made live: 28 Jul 2009 13:05
URI: http://nora.nerc.ac.uk/id/eprint/7838

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