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Clockwise rotation of the entire Oman Ophiolite occurred in a suprasubduction zone setting

Antony Morris, Matthew Meyer, Mark W. Anderson and Christopher J. MacLeod
Clockwise rotation of the entire Oman Ophiolite occurred in a suprasubduction zone setting
Geology (Boulder) (October 2016) 44 (12): 1055-1058

Abstract

The Oman ophiolite provides a natural laboratory for understanding oceanic lithospheric processes. Previous paleomagnetic and structural investigations have been used to support a model involving rotation of the ophiolite during formation at a mid-oceanic microplate. However, recent geochemical evidence indicates that the ophiolite instead formed in a nascent forearc environment, opening the potential for alternative rotation mechanisms. Central to the conundrum is the contrast between ESE to SE magnetizations and NNW magnetizations from the northern and southern ophiolitic massifs, respectively, attributed previously to either differential tectonic rotations during spreading or complete emplacement-related remagnetization of the southern massifs. Here we report new paleomagnetic data from lower crustal rocks of the southern massifs that resolve this problem. Sampling of a continuous section in Wadi Abyad reveals ENE magnetizations in the dike rooting zone at the top of the lower crust that change systematically downwards to NNW directions in underlying foliated and layered gabbros. This is consistent only with remagnetization from the base upwards, replacing early remanences in layered and foliated gabbros completely but preserving original ENE magnetizations at higher levels. Comparison with new data from Wadi Khafifah provides a positive fold test that shows that this event occurred before late Campanian structural disruption of the regional orientation of the petrologic Moho. These data show that the entire ophiolite experienced large intraoceanic clockwise rotation prior to partial remagnetization, leading to a new tectonic model in which formation, rotation, and emplacement of the ophiolite are all linked to Late Cretaceous motion of Arabia and roll-back of the Oman subduction zone.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 44
Serial Issue: 12
Title: Clockwise rotation of the entire Oman Ophiolite occurred in a suprasubduction zone setting
Affiliation: Plymouth University, School of Geography, Earth and Environmental Sciences, Plymouth, United Kingdom
Pages: 1055-1058
Published: 20161020
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 30
Accession Number: 2017-002990
Categories: Solid-earth geophysicsIgneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Data Repository item 2016351
Illustration Description: illus. incl. geol. sketch map
N23°00'00" - N24°00'00", E57°30'00" - E58°30'00"
Secondary Affiliation: Cardiff University, GBR, United Kingdom
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2022, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201703
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