Macrostructural and microstructural architecture of the Karakoram fault: Relationship between magmatism and strike-slip faulting
A key factor in interpreting the significance of large-scale strike-slip faults in models of continental deformation is an understanding of the temporal relationship between faulting and magmatism. Knowledge of when a strike-slip fault initiated is essential in order to determine its long-term slip...
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| Format: | Journal article |
| Language: | English |
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2007
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| _version_ | 1826274526537711616 |
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| author | Phillips, R Searle, M |
| author_facet | Phillips, R Searle, M |
| author_sort | Phillips, R |
| collection | OXFORD |
| description | A key factor in interpreting the significance of large-scale strike-slip faults in models of continental deformation is an understanding of the temporal relationship between faulting and magmatism. Knowledge of when a strike-slip fault initiated is essential in order to determine its long-term slip rate and its significance in accommodating strain. We review key structural criteria that identify whether magmatism is prekinematic or synkinematic with faulting and apply these criteria to a major Tibet-bounding strike-slip fault. Along the Karakoram fault, in western Tibet, opinion is divided between (1) those advocating that magmatism and shearing were coeval, in which case the youngest U-Pb crystallization age provides a minimum age of shear, and (2) those advocating that magmatism preceded strike-slip shearing, in which case the youngest U-Pb crystallization age provides a maximum age of shear. Fault zone rocks within the central segment of the fault are variably deformed, displaying high- to low-temperature solid-state fabrics. Mylonites indicate subsolidus noncoaxial deformation at temperatures that have not exceeded greenschist - lower amphibolite facies. There is no evidence for submagmatic deformation, and there are no textural or structural indicators that suggest synkinematic magmatism. Consequently, magmatism preceded shearing suggesting that the U-Pb age of proximal leucogranites sets a maximum age for shear. Coupled with a limited offset (<150 km), these data confirm a low long-term slip rate for the Karakoram fault (3-10 mm/yr). Consequently, the fault is unlikely to have played a significant role in accommodating strain during the Indo-Asian collision, and thus its role in suggested extrusion models of deformation is limited. Copyright 2007 by the American Geophysical Union. |
| first_indexed | 2024-03-06T22:44:46Z |
| format | Journal article |
| id | oxford-uuid:5ccbae1f-ba12-4541-bb3a-f5b5aa84a03b |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-06T22:44:46Z |
| publishDate | 2007 |
| record_format | dspace |
| spelling | oxford-uuid:5ccbae1f-ba12-4541-bb3a-f5b5aa84a03b2022-03-26T17:30:21ZMacrostructural and microstructural architecture of the Karakoram fault: Relationship between magmatism and strike-slip faultingJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:5ccbae1f-ba12-4541-bb3a-f5b5aa84a03bEnglishSymplectic Elements at Oxford2007Phillips, RSearle, MA key factor in interpreting the significance of large-scale strike-slip faults in models of continental deformation is an understanding of the temporal relationship between faulting and magmatism. Knowledge of when a strike-slip fault initiated is essential in order to determine its long-term slip rate and its significance in accommodating strain. We review key structural criteria that identify whether magmatism is prekinematic or synkinematic with faulting and apply these criteria to a major Tibet-bounding strike-slip fault. Along the Karakoram fault, in western Tibet, opinion is divided between (1) those advocating that magmatism and shearing were coeval, in which case the youngest U-Pb crystallization age provides a minimum age of shear, and (2) those advocating that magmatism preceded strike-slip shearing, in which case the youngest U-Pb crystallization age provides a maximum age of shear. Fault zone rocks within the central segment of the fault are variably deformed, displaying high- to low-temperature solid-state fabrics. Mylonites indicate subsolidus noncoaxial deformation at temperatures that have not exceeded greenschist - lower amphibolite facies. There is no evidence for submagmatic deformation, and there are no textural or structural indicators that suggest synkinematic magmatism. Consequently, magmatism preceded shearing suggesting that the U-Pb age of proximal leucogranites sets a maximum age for shear. Coupled with a limited offset (<150 km), these data confirm a low long-term slip rate for the Karakoram fault (3-10 mm/yr). Consequently, the fault is unlikely to have played a significant role in accommodating strain during the Indo-Asian collision, and thus its role in suggested extrusion models of deformation is limited. Copyright 2007 by the American Geophysical Union. |
| spellingShingle | Phillips, R Searle, M Macrostructural and microstructural architecture of the Karakoram fault: Relationship between magmatism and strike-slip faulting |
| title | Macrostructural and microstructural architecture of the Karakoram fault: Relationship between magmatism and strike-slip faulting |
| title_full | Macrostructural and microstructural architecture of the Karakoram fault: Relationship between magmatism and strike-slip faulting |
| title_fullStr | Macrostructural and microstructural architecture of the Karakoram fault: Relationship between magmatism and strike-slip faulting |
| title_full_unstemmed | Macrostructural and microstructural architecture of the Karakoram fault: Relationship between magmatism and strike-slip faulting |
| title_short | Macrostructural and microstructural architecture of the Karakoram fault: Relationship between magmatism and strike-slip faulting |
| title_sort | macrostructural and microstructural architecture of the karakoram fault relationship between magmatism and strike slip faulting |
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