Age constraints on the deformation style of the South Tibetan Detachment System in Garhwal Himalaya

Montemagni, Chiara; Iaccarino, Salvatore; Montomoli, Chiara; Carosi, Rodolfo; Jain, Arvind K; Villa, Igor Maria (2018). Age constraints on the deformation style of the South Tibetan Detachment System in Garhwal Himalaya. Italian journal of geosciences, 137(2), pp. 175-187. Società Geologica Italiana 10.3301/IJG.2018.07

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In the Garhwal Himalaya, the Malari granite, a small pluton, intrudes the upper portion of the Greater Himalayan Sequence (GHS) and is deformed in the South Tibetan Detachment System (STDS) shearing. In the present work, we undertook a multidisciplinary approach involving microstructural, chemical and geochronological analyses of the samples in order to constrain the timing of shearing along the STDS. Microstructural observations of samples suggest a switch in deformation features with structural position from the structurally upper samples to the structurally lower one. X-ray maps and electron microprobe analyses reveal a quite uniform chemical composition of muscovite in the three selected samples. 40Ar/39Ar muscovite ages constrain the waning stages of ductile deformation: in rocks ductilely deformed by the STDS activity, they record recrystallization at 16.0-16.5 Ma; the age of static muscovite grown after sillimanite at 14.3 Ma post-dates cessation of movement on the STDS and pre-dates the main activity of the Main Central Thrust in the Western Himalaya.

Item Type:	Journal Article (Original Article)
Division/Institute:	08 Faculty of Science > Institute of Geological Sciences 08 Faculty of Science > Institute of Geological Sciences > Isotope Geology 08 Faculty of Science > Other Institutions > Emeriti, Faculty of Science
UniBE Contributor:	Villa, Igor Maria
Subjects:	500 Science > 550 Earth sciences & geology
ISSN:	2038-1719
Publisher:	Società Geologica Italiana
Funders:	[UNSPECIFIED] MIUR Italia
Language:	English
Submitter:	Igor Maria Villa-Toscani
Date Deposited:	18 Jun 2019 13:59
Last Modified:	05 Dec 2022 15:28
Publisher DOI:	10.3301/IJG.2018.07
URI:	https://boris.unibe.ch/id/eprint/129753