The Geodynamic Significance of Continental UHP Exhumation: new Constraints From the Tso Morari Complex, NW Himalaya

Bidgood, Anna K.; Parsons, Andrew J.; Roberts, Nick M.W.; Waters, Dave; Tapster, Simon; Gopon, Phillip. 2024 The Geodynamic Significance of Continental UHP Exhumation: new Constraints From the Tso Morari Complex, NW Himalaya. Tectonics, 43 (5), e2023TC007976. https://doi.org/10.1029/2023TC007976

Before downloading, please read NORA policies.

Preview

Text (Open Access Paper)
Tectonics - 2024 - Bidgood - The Geodynamic Significance of Continental UHP Exhumation New Constraints From the Tso Morari.pdf - Published Version
Available under License Creative Commons Attribution 4.0.
Download (11MB) | Preview

Official URL: http://dx.doi.org/10.1029/2023TC007976

Abstract/Summary

The burial and exhumation of continental crust to and from ultrahigh-pressure (UHP) is an important orogenic process, often interpreted with respect to the onset and/or subduction dynamics of continent-continent collision. Here, we investigate the timing and significance of UHP metamorphism and exhumation of the Tso Morari complex, North-West Himalaya. We present new petrochronological analyses of mafic eclogites and their host-rock gneisses, combining U-Pb zircon, rutile and xenotime geochronology (high-precision CA-ID-TIMS and high-spatial resolution LA-ICP-MS), garnet element maps, and petrographic observations. Zircon from mafic eclogite have a CA-ID-TIMS age of 46.91 ± 0.07 Ma, with REE profiles indicative of growth at eclogite facies conditions. Those ages overlap with zircon rim ages (48.9 ± 1.2 Ma, LA-ICP-MS) and xenotime ages (47.4 ± 1.4 Ma; LA-ICP-MS) from the hosting Puga gneiss, which grew during breakdown of UHP garnet rims. We argue that peak zircon growth at 47–46 Ma corresponds to the onset of exhumation from UHP conditions. Subsequent exhumation through the rutile closure temperature, is constrained by new dates of 40.4 ± 1.7 and 36.3 ± 3.8 Ma (LA-ICP-MS). Overlapping ages from Kaghan imply a coeval time-frame for the onset of UHP exhumation across the NW Himalaya. Furthermore, our regional synthesis demonstrates a causative link between changes in the subduction dynamics of the India-Asia collision zone at 47–46 Ma and the resulting mid-Eocene plate network reorganization. The onset of UHP exhumation therefore provides a tightly constrained time-stamp significant geodynamic shifts within the orogen and wider plate network.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1029/2023TC007976
ISSN:	0278-7407
Date made live:	06 Jun 2024 10:32 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/537523

Item Type:

Publication - Article

Digital Object Identifier (DOI):

https://doi.org/10.1029/2023TC007976

ISSN:

0278-7407

Date made live:

06 Jun 2024 10:32 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/537523