DOI: 10.1016/j.tecto.2020.228641
论文题名: Extrusion kinematics of UHP terrane in a collisional orogen: EBSD and microstructure-based approach from the Tso Morari Crystallines (Ladakh Himalaya)
作者: Dutta D. ; Mukherjee S.
刊名: Tectonophysics
ISSN: 00401951
出版年: 2021
卷: 800 语种: 英语
中文关键词: Channel flow
; CVA analysis
; Opposite shear
; Partial melting
; Quartz CPO
; Triclinic 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
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. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/170799
Appears in Collections: 气候变化与战略
There are no files associated with this item.
作者单位: Department of Earth Sciences, Indian Institute of Technology Bombay, Powai, Mumbai, Maharashtra 400 076, India
Recommended Citation:
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]. Tectonophysics,2021-01-01,800