DOI: 10.1007/s00531-013-0892-6
Scopus记录号: 2-s2.0-84884414201
论文题名: Deformation style in the Munsiari Thrust Zone: A study in the Madlakia-Munsiari-Dhapa section in north-eastern Kumaun Himalaya
作者: Moharana A. ; Mishra A. ; Srivastava D.C.
刊名: International Journal of Earth Sciences
ISSN: 14373254
出版年: 2013
卷: 102, 期: 7 起始页码: 1837
结束页码: 1849
语种: 英语
英文关键词: Damage zone
; Ductile shearing
; Himalaya
; Main Central Thrust
; Pre-Himalayan orogeny
; Sheath folds
Scopus关键词: crystalline rock
; ductile deformation
; fault zone
; folding
; footwall
; gneiss
; hanging wall
; migmatite
; orogeny
; quartzite
; shear zone
; Himalayas
; India
; Kumaun Himalayas
; Lesser Himalayas
; Main Central Thrust Zone
; Uttarakhand
英文摘要: The Main Central Thrust demarcates the boundary between the Lesser Himalaya and the Higher Himalaya in the Himalayan orogen. Several definitions of the Main Central Thrust have been proposed since it was originally described as the southern boundary of the crystalline rocks (the Main Central Thrust mass) in the Kumaun-Garhwal Himalaya. The long-held contention that the Munsiari Thrust represents the Main Central Thrust has been negated by recent isotopic studies. One way to define the Main Central Thrust is that it is a ductile shear zone that is delimited by the Munsiari Thrust (MCT-I) in south and the Vaikrita Thrust (MCT-II) in north. The alternative proposition that the Vaikrita Thrust represents the Main Central Thrust is fraught with practical limitations in many parts of the Himalaya, including the study area. In the metamorphic rocks bounded between the Vaikrita Thrust and the Munsiari Thrust, the isoclinal folds of the earliest phase are routinely ascribed to the pre-Himalayan orogeny, whereas all subsequent folding phases are attributed to the Himalayan orogeny. This article elucidates the structural characteristics of the kilometre-thick Munsiari Thrust Zone and revisits the issue of pre-Himalayan orogenic signatures in the thrust zone. With the help of high-resolution field mapping and the analyses of mesoscopic scale structures, we demonstrate that the Munsiari Thrust is a typical fault zone that is made up of a fault core and two damage zones. The fault core traces the boundary between the quartzite and the biotite-gneiss. The damage zones consist of the low-grade metasedimentary rocks in the footwall and the gneiss-migmatite in the hanging wall. The entire fault zone shares an essentially common history of progressive ductile shearing. Successively developed mesoscopic folds trace various stages of progressive ductile shearing in the damage zones. Two recognizable stages of the shearing are represented by the early isoclinal folds and the late kink folds. As the strain during progressive deformation achieved the levels that were too high for accommodation by ductile flow, it was released by development of a tectonic dislocation along a mechanically weak boundary, the Munsiari Thrust. The isoclinal folds and the Munsiari Thrust were developed at different stages of a common progressive deformation during the Himalayan orogeny. Contrary to the popular notion of consistency with respect to orientation, the stretching lineations show large directional variability due to distortion during the late folding. © 2013 Springer-Verlag Berlin Heidelberg. URL: https://www.scopus.com/inward/record.uri?eid=2-s2.0-84884414201&doi=10.1007%2fs00531-013-0892-6&partnerID=40&md5=dd84d0c25e42d6dabdd0c13e88a0965c
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/70514
Appears in Collections: 影响、适应和脆弱性 气候减缓与适应
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作者单位: Department of Earth Sciences, Indian Institute of Technology Roorkee, Roorkee- 247 667, India
Recommended Citation:
Moharana A.,Mishra A.,Srivastava D.C.. Deformation style in the Munsiari Thrust Zone: A study in the Madlakia-Munsiari-Dhapa section in north-eastern Kumaun Himalaya[J]. International Journal of Earth Sciences,2013-01-01,102(7)