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DOI | 10.1016/j.tecto.2020.228641 |
Extrusion kinematics of UHP terrane in a collisional orogen: EBSD and microstructure-based approach from the Tso Morari Crystallines (Ladakh Himalaya) | |
Dutta D.; Mukherjee S. | |
发表日期 | 2021 |
ISSN | 00401951 |
卷号 | 800 |
英文摘要 | Several extrusion mechanisms have been proposed to explain the occurrences of ultra-high pressure (UHP) rocks at collisional margins. Here we assess the suitability of the channel flow model of extrusion for the Tso Morari Crystallines (TMC) by investigating the syn-extrusion deformation kinematics of the UHP eclogite-bearing gneiss that dominates the TMC. Samples collected from the two transects viz. Sumdo-Karzok and Sumdo-Debring, have been examined. The channel flow model predicts high simple shear component at the channel margins during extrusion. Gneisses near the upper margin of the subduction channel – also the northern margin of the TMC on map – support this claim and exhibit closely spaced shear planes, and elevated fluid activity as revealed by X-ray diffraction results. Quartz grain parameters e.g. Feret diameter, aspect ratio, and vector mean strength measured from oriented thin-sections of the gneiss do not exhibit distinct pattern of variation of deformation intensity across the TMC. EBSD-based low-angle intragranular 'neighbor to neighbor' misorientation analysis and micro-textural evidences of incipient partial melting in the gneiss reflect temperatures >600 °C. We propose that return flow and buoyancy of the subducted continental crust triggered the extrusion, which was then facilitated by the Indo-Eurasia collision. The mechanism could thus be a combination of both channel flow and ductile wedge extrusion. Continued convergence possibly promoted non-planar triclinic transpression – also evident from the crystallographic vorticity axis (CVA) analysis – such that the extrusion direction varied spatially, producing the diverse shear senses observed at both meso- and micro-scales. © 2020 Elsevier B.V. |
关键词 | Channel flowCVA analysisOpposite shearPartial meltingQuartz CPOTriclinic flow |
英文关键词 | Aspect ratio; Channel flow; Deformation; Kinematics; Shear flow; Channel margins; Deformation intensity; Extrusion deformation; Mis-orientation; Partial melting; Subducted continental crust; Subduction channels; Ultrahigh pressure rocks; Extrusion; channel flow; continental collision; crystalline rock; extrusion; gneiss; kinematics; microstructure; partial melting; quartz; scanning electron microscopy; shear; terrane; Himalayas; Ladakh Himalayas |
语种 | 英语 |
来源期刊 | Tectonophysics |
文献类型 | 期刊论文 |
条目标识符 | http://gcip.llas.ac.cn/handle/2XKMVOVA/207966 |
作者单位 | Department of Earth Sciences, Indian Institute of Technology Bombay, Powai, Mumbai, Maharashtra 400 076, India |
推荐引用方式 GB/T 7714 | Dutta D.,Mukherjee S.. Extrusion kinematics of UHP terrane in a collisional orogen: EBSD and microstructure-based approach from the Tso Morari Crystallines (Ladakh Himalaya)[J],2021,800. |
APA | Dutta D.,&Mukherjee S..(2021).Extrusion kinematics of UHP terrane in a collisional orogen: EBSD and microstructure-based approach from the Tso Morari Crystallines (Ladakh Himalaya).Tectonophysics,800. |
MLA | Dutta D.,et al."Extrusion kinematics of UHP terrane in a collisional orogen: EBSD and microstructure-based approach from the Tso Morari Crystallines (Ladakh Himalaya)".Tectonophysics 800(2021). |
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