Three-dimensional vorticity and time-constrained evolution of the Main Central Thrust zone, Garhwal Himalaya (NW India).
Publisher DOI
Abstract
The use of porphyroclasts analysis for vorticity estimates is limited by the extrapolation to three dimensions of the two dimensional thin-section analysis of rigid clasts. We propose an alternative approach based on the use of X-ray micro computed tomography that offers a 3D view and thus considerably decreases the limitations of the method. Two mylonitic orthogneisses from the Munsiari Thrust, the lower boundary of the top-to-the-SW km-thick Main Central Thrust zone in the Indian Himalaya, containing K-feldspar porphyroclasts yield a kinematic vorticity ranging between 0.49 and 0.57. 40Ar/39Ar dating constrains the biotite growth on the main foliation at 4.8 ± 0.02 Ma.
Adding as much information as possible to a shear zone and relating them to different pressure and temperature conditions of shear episodes recorded besides by age variations of micas is a key point to keep in mind when debating the non-cylindrical nature of Himalayan orogen.
Adding as much information as possible to a shear zone and relating them to different pressure and temperature conditions of shear episodes recorded besides by age variations of micas is a key point to keep in mind when debating the non-cylindrical nature of Himalayan orogen.
Date Issued
2020
Publication Type
Article
Subject(s)
Subjects
Himalaya
•
Main Central Thrust
•
Vorticity
•
40Ar/39Ar dating
Language(s)
en
Author(s)
Montemagni, Chiara | |
Carosi, Rodolfo | |
Fusi, Nicoletta | |
Iaccarino, Salvatore | |
Montomoli, Chiara | |
Zanchetta, Stefano |
Additional Credits
Journal
Terra nova
Publisher
Wiley
ISSN
0954-4879
Access(Rights)
open.access