The Dutung-Thaktote extensional fault zone and nappe structures documented by illite crystallinity and clay-mineral paragenesis in the Tethys Himalaya between Spiti river and Tso Morari, NW India

Details

Serval ID
serval:BIB_ECD175857E01
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
The Dutung-Thaktote extensional fault zone and nappe structures documented by illite crystallinity and clay-mineral paragenesis in the Tethys Himalaya between Spiti river and Tso Morari, NW India
Journal
Schweizerische Mineralogische und Petrographische Mitteilungen
Author(s)
Girard M., Steck A., Thélin P.
ISSN-L
0036-7699
Publication state
Published
Issued date
1999
Peer-reviewed
Oui
Volume
79
Pages
419-430
Language
english
Abstract
Numerous measurements by XRD of the Scherrer width at half-peak height (001 reflection of illite), coupled with analyses of clay-size
assemblages, provide evidence for strong variations in the conditions of low temperature metamorphism in the Tethyan Himalaya metasediments between the Spiti river and the Tso Morari.
Three sectors can be distinguished along the Spiti river-Tso Morari
transect. In the SW, the Takling and Parang La area is characterised by a metamorphism around anchizone-epizone boundary conditions. Further north, in the Dutung area, the metamorphic grade abruptly decreases to weak diagenesis, with the presence of mixed-layered clay phases. At the end of the profile towards the NE, a progressive metamorphic increase up to greenschist facies is recorded, marked by the appearance of biotite and chloritoid. The combination of these data with the structural. observations permits to propose that a nappe stack has been crosscut by the younger Dutung-Thaktote extensional fault zone (DTFZ). The change in metamorphism across this zone helps to assess the displacements which occurred during synorogenic extension. In the SW and NE parts of the studied transect, a burial of 12 km has been estimated, assuming a
geothermal gradient of 25 degrees C/km. In the SW part, this burial is due to the juxtaposition of the Shikar Beh and Mata nappes and in the NE part, solely to burial beneath the Mata nappe. In the central part of the profile, the effect of the DTFZ is to bring down diagenetic
sediments in-between the two aforesaid metamorphic zones. The offset along the Dutung-Thaktote normal faults is estimated at 16 km.
Create date
07/12/2012 15:56
Last modification date
20/08/2019 16:14
Usage data