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Synchronous N-S and E-W extension at the Tibet-to-Himalaya transition in NW Bhutan

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Synchronous N-S and E-W extension at the Tibet-to-Himalaya transition in NW Bhutan. / Cooper, Frances J; Hodges, Kip V; Parrish, Randall; Roberts, Nick; Horstwood, Matthew.

In: Tectonics, Vol. 34, No. 7, 07.2015, p. 1375-1395.

Research output: Contribution to journalArticle

Harvard

Cooper, FJ, Hodges, KV, Parrish, R, Roberts, N & Horstwood, M 2015, 'Synchronous N-S and E-W extension at the Tibet-to-Himalaya transition in NW Bhutan' Tectonics, vol. 34, no. 7, pp. 1375-1395. https://doi.org/10.1002/2014TC003712

APA

Cooper, F. J., Hodges, K. V., Parrish, R., Roberts, N., & Horstwood, M. (2015). Synchronous N-S and E-W extension at the Tibet-to-Himalaya transition in NW Bhutan. Tectonics, 34(7), 1375-1395. https://doi.org/10.1002/2014TC003712

Vancouver

Cooper FJ, Hodges KV, Parrish R, Roberts N, Horstwood M. Synchronous N-S and E-W extension at the Tibet-to-Himalaya transition in NW Bhutan. Tectonics. 2015 Jul;34(7):1375-1395. https://doi.org/10.1002/2014TC003712

Author

Cooper, Frances J ; Hodges, Kip V ; Parrish, Randall ; Roberts, Nick ; Horstwood, Matthew. / Synchronous N-S and E-W extension at the Tibet-to-Himalaya transition in NW Bhutan. In: Tectonics. 2015 ; Vol. 34, No. 7. pp. 1375-1395.

Bibtex

@article{efa0f85cbd15429390e8754ed64d4661,
title = "Synchronous N-S and E-W extension at the Tibet-to-Himalaya transition in NW Bhutan",
abstract = "Despite ~50 Myr of continuous continent-continent collision, contractional structures in the Himalayan-Tibetan orogen are today limited to the northern and southern margins of the system, while extension dominates much of the interior. On the Tibetan Plateau, Cenozoic E-W extension has been accommodated by strike-slip faults and extensional grabens, while N-S extension at the Tibet-to-Himalaya transition has been accommodated by the South Tibetan fault system (STFS). The genetic relationship between N-S and E-W extension is disputed, although age constraints indicate temporal overlap of at least 7 Myr. In NW Bhutan the two intersect where the STFS basal detachment is cut by the Yadong cross structure (YCS), an extensional half graben that provides a rare opportunity to constrain relative timings. We report U-Pb zircon dates from four STFS footwall leucogranites consistent with episodic magmatism during the middle-late Miocene and in situ U(-Th)-Pb monazite and xenotime dates from three metasedimentary rocks ranging from late Oligocene to middle Miocene. We suggest that amphibolite facies footwall metamorphism was ongoing at the time the basal STFS detachment initiated as a ductile structure in the middle-late Miocene. Late-stage granitic intrusions may reflect footwall melting during extensional exhumation along the STFS, but post-metamorphic and post-intrusion fabrics suggest that most displacement occurred after emplacement of the youngest granites. Some of the oldest YCS-related fabrics are found in a deformed 14 Ma leucogranite, implying middle Miocene ductile deformation. This observation, along with evidence for subsequent brittle YCS deformation, suggests that N-S and E-W extensional structures in the area had protracted and overlapping deformation histories.",
keywords = "South Tibetan fault system, Yadong cross structure, leucogranite, geochronology, zircon, monazite",
author = "Cooper, {Frances J} and Hodges, {Kip V} and Randall Parrish and Nick Roberts and Matthew Horstwood",
year = "2015",
month = "7",
doi = "10.1002/2014TC003712",
language = "English",
volume = "34",
pages = "1375--1395",
journal = "Tectonics",
issn = "0278-7407",
number = "7",

}

RIS - suitable for import to EndNote

TY - JOUR

T1 - Synchronous N-S and E-W extension at the Tibet-to-Himalaya transition in NW Bhutan

AU - Cooper, Frances J

AU - Hodges, Kip V

AU - Parrish, Randall

AU - Roberts, Nick

AU - Horstwood, Matthew

PY - 2015/7

Y1 - 2015/7

N2 - Despite ~50 Myr of continuous continent-continent collision, contractional structures in the Himalayan-Tibetan orogen are today limited to the northern and southern margins of the system, while extension dominates much of the interior. On the Tibetan Plateau, Cenozoic E-W extension has been accommodated by strike-slip faults and extensional grabens, while N-S extension at the Tibet-to-Himalaya transition has been accommodated by the South Tibetan fault system (STFS). The genetic relationship between N-S and E-W extension is disputed, although age constraints indicate temporal overlap of at least 7 Myr. In NW Bhutan the two intersect where the STFS basal detachment is cut by the Yadong cross structure (YCS), an extensional half graben that provides a rare opportunity to constrain relative timings. We report U-Pb zircon dates from four STFS footwall leucogranites consistent with episodic magmatism during the middle-late Miocene and in situ U(-Th)-Pb monazite and xenotime dates from three metasedimentary rocks ranging from late Oligocene to middle Miocene. We suggest that amphibolite facies footwall metamorphism was ongoing at the time the basal STFS detachment initiated as a ductile structure in the middle-late Miocene. Late-stage granitic intrusions may reflect footwall melting during extensional exhumation along the STFS, but post-metamorphic and post-intrusion fabrics suggest that most displacement occurred after emplacement of the youngest granites. Some of the oldest YCS-related fabrics are found in a deformed 14 Ma leucogranite, implying middle Miocene ductile deformation. This observation, along with evidence for subsequent brittle YCS deformation, suggests that N-S and E-W extensional structures in the area had protracted and overlapping deformation histories.

AB - Despite ~50 Myr of continuous continent-continent collision, contractional structures in the Himalayan-Tibetan orogen are today limited to the northern and southern margins of the system, while extension dominates much of the interior. On the Tibetan Plateau, Cenozoic E-W extension has been accommodated by strike-slip faults and extensional grabens, while N-S extension at the Tibet-to-Himalaya transition has been accommodated by the South Tibetan fault system (STFS). The genetic relationship between N-S and E-W extension is disputed, although age constraints indicate temporal overlap of at least 7 Myr. In NW Bhutan the two intersect where the STFS basal detachment is cut by the Yadong cross structure (YCS), an extensional half graben that provides a rare opportunity to constrain relative timings. We report U-Pb zircon dates from four STFS footwall leucogranites consistent with episodic magmatism during the middle-late Miocene and in situ U(-Th)-Pb monazite and xenotime dates from three metasedimentary rocks ranging from late Oligocene to middle Miocene. We suggest that amphibolite facies footwall metamorphism was ongoing at the time the basal STFS detachment initiated as a ductile structure in the middle-late Miocene. Late-stage granitic intrusions may reflect footwall melting during extensional exhumation along the STFS, but post-metamorphic and post-intrusion fabrics suggest that most displacement occurred after emplacement of the youngest granites. Some of the oldest YCS-related fabrics are found in a deformed 14 Ma leucogranite, implying middle Miocene ductile deformation. This observation, along with evidence for subsequent brittle YCS deformation, suggests that N-S and E-W extensional structures in the area had protracted and overlapping deformation histories.

KW - South Tibetan fault system

KW - Yadong cross structure

KW - leucogranite

KW - geochronology

KW - zircon

KW - monazite

U2 - 10.1002/2014TC003712

DO - 10.1002/2014TC003712

M3 - Article

VL - 34

SP - 1375

EP - 1395

JO - Tectonics

T2 - Tectonics

JF - Tectonics

SN - 0278-7407

IS - 7

ER -