Crustal stacking and expulsion tectonics during continental subduction: P-T deformation constraints from Oman
The northeastern continental margin of Oman in the Saih Hatat region is characterized by high-pressure (HP) chloritoid- or carpholite-bearing metasediments and highly deformed mafic eclogites and blueschists in a series of tectonic units bounded by high-strain ductile shear zones. New data on the up...
| Main Authors: | , , , |
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| Format: | Journal article |
| Language: | English |
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2010
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| _version_ | 1826285680048734208 |
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| author | Agard, P Searle, M Alsop, G Dubacq, B |
| author_facet | Agard, P Searle, M Alsop, G Dubacq, B |
| author_sort | Agard, P |
| collection | OXFORD |
| description | The northeastern continental margin of Oman in the Saih Hatat region is characterized by high-pressure (HP) chloritoid- or carpholite-bearing metasediments and highly deformed mafic eclogites and blueschists in a series of tectonic units bounded by high-strain ductile shear zones. New data on the upper cover units of this HP nappe stack indicate that all of them underwent similar P conditions to the underlying Hulw structural unit (with a cooler exhumation pressure-temperature path). Early SSW directed crustal thickening during ophiolite emplacement created recumbent folds and strong schistose fabrics in these Permian-Mesozoic shelf carbonates and was followed by later NNE dipping normal sense shear zones and normal faults. The Mayh unit shows high strain in a 15-25 km long sheath fold that likely formed at carpholite grade pressures of 8-10 kbar. We show that there are no significant P differences across the Hulw shear zone (upper plate-lower plate discontinuity) or between the overlying Mayh, Yenkit-Yiti, and Ruwi units. Postpeak metamorphic exhumation of the HP rocks was therefore accomplished by bottom-to-SSW (rather than top-to-NNE) active footwall extrusion beneath a fixed, static, passive hanging wall. Footwall uplift beneath these passive roof faults resulted in progressive expulsion of the HP rocks from depths of ∼80-90 km (eclogites) and mainly 30-35 km (blueschists and chloritoid-/carpholite-bearing units) during the Campanian-Early Maastrichtian. Oman thus provides a detailed record of how continental material (thick platform shelf carbonates) progressively jammed a subduction zone and emphasizes the contrasting behavior between cover units and their underlying basement. Copyright 2010 by the American Geophysical Union. |
| first_indexed | 2024-03-07T01:32:27Z |
| format | Journal article |
| id | oxford-uuid:940efe4c-5778-4730-89d9-bfb1937eaf25 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T01:32:27Z |
| publishDate | 2010 |
| record_format | dspace |
| spelling | oxford-uuid:940efe4c-5778-4730-89d9-bfb1937eaf252022-03-26T23:36:35ZCrustal stacking and expulsion tectonics during continental subduction: P-T deformation constraints from OmanJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:940efe4c-5778-4730-89d9-bfb1937eaf25EnglishSymplectic Elements at Oxford2010Agard, PSearle, MAlsop, GDubacq, BThe northeastern continental margin of Oman in the Saih Hatat region is characterized by high-pressure (HP) chloritoid- or carpholite-bearing metasediments and highly deformed mafic eclogites and blueschists in a series of tectonic units bounded by high-strain ductile shear zones. New data on the upper cover units of this HP nappe stack indicate that all of them underwent similar P conditions to the underlying Hulw structural unit (with a cooler exhumation pressure-temperature path). Early SSW directed crustal thickening during ophiolite emplacement created recumbent folds and strong schistose fabrics in these Permian-Mesozoic shelf carbonates and was followed by later NNE dipping normal sense shear zones and normal faults. The Mayh unit shows high strain in a 15-25 km long sheath fold that likely formed at carpholite grade pressures of 8-10 kbar. We show that there are no significant P differences across the Hulw shear zone (upper plate-lower plate discontinuity) or between the overlying Mayh, Yenkit-Yiti, and Ruwi units. Postpeak metamorphic exhumation of the HP rocks was therefore accomplished by bottom-to-SSW (rather than top-to-NNE) active footwall extrusion beneath a fixed, static, passive hanging wall. Footwall uplift beneath these passive roof faults resulted in progressive expulsion of the HP rocks from depths of ∼80-90 km (eclogites) and mainly 30-35 km (blueschists and chloritoid-/carpholite-bearing units) during the Campanian-Early Maastrichtian. Oman thus provides a detailed record of how continental material (thick platform shelf carbonates) progressively jammed a subduction zone and emphasizes the contrasting behavior between cover units and their underlying basement. Copyright 2010 by the American Geophysical Union. |
| spellingShingle | Agard, P Searle, M Alsop, G Dubacq, B Crustal stacking and expulsion tectonics during continental subduction: P-T deformation constraints from Oman |
| title | Crustal stacking and expulsion tectonics during continental subduction: P-T deformation constraints from Oman |
| title_full | Crustal stacking and expulsion tectonics during continental subduction: P-T deformation constraints from Oman |
| title_fullStr | Crustal stacking and expulsion tectonics during continental subduction: P-T deformation constraints from Oman |
| title_full_unstemmed | Crustal stacking and expulsion tectonics during continental subduction: P-T deformation constraints from Oman |
| title_short | Crustal stacking and expulsion tectonics during continental subduction: P-T deformation constraints from Oman |
| title_sort | crustal stacking and expulsion tectonics during continental subduction p t deformation constraints from oman |
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