Dating the Indian continental subduction and collisional thickening in the northwest Himalaya: Multichronology of the Tso Morari eclogites

Abstract

Research Article| June 01, 2000 Dating the Indian continental subduction and collisional thickening in the northwest Himalaya: Multichronology of the Tso Morari eclogites Julia de Sigoyer; Julia de Sigoyer 1Institut de Géologie, 11 rue E. Argand, 2007 Neuchâtel, Switzerland Search for other works by this author on: GSW Google Scholar Valérie Chavagnac; Valérie Chavagnac 2Isotopengeologie, Erlachstrasse 9a, 3012 Bern, Switzerland Search for other works by this author on: GSW Google Scholar Janne Blichert-Toft; Janne Blichert-Toft 3Centre National de la Recherche Scientifique, 69364 Lyon Cedex 07, France Search for other works by this author on: GSW Google Scholar Igor M. Villa; Igor M. Villa 2Isotopengeologie, Erlachstrasse 9a, 3012 Bern, Switzerland Search for other works by this author on: GSW Google Scholar Béatrice Luais; Béatrice Luais 3Centre National de la Recherche Scientifique, 69364 Lyon Cedex 07, France Search for other works by this author on: GSW Google Scholar Stéphane Guillot; Stéphane Guillot 3Centre National de la Recherche Scientifique, 69364 Lyon Cedex 07, France Search for other works by this author on: GSW Google Scholar Michael Cosca; Michael Cosca 4Institut de Minéralogie et Pétrographie, 1015 Lausanne, Switzerland Search for other works by this author on: GSW Google Scholar Georges Mascle Georges Mascle 5Centre National de la Recherche Scientifique, Institut Dolomieu, 38100 Grenoble, France Search for other works by this author on: GSW Google Scholar Geology (2000) 28 (6): 487–490. https://doi.org/10.1130/0091-7613(2000)28<487:DTICSA>2.0.CO;2 Article history received: 13 Oct 1999 rev-recd: 28 Feb 2000 accepted: 09 Mar 2000 first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Julia de Sigoyer, Valérie Chavagnac, Janne Blichert-Toft, Igor M. Villa, Béatrice Luais, Stéphane Guillot, Michael Cosca, Georges Mascle; Dating the Indian continental subduction and collisional thickening in the northwest Himalaya: Multichronology of the Tso Morari eclogites. Geology 2000;; 28 (6): 487–490. doi: https://doi.org/10.1130/0091-7613(2000)28<487:DTICSA>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Multichronometric studies of the low-temperature eclogitic Tso Morari unit (Ladakh, India) place timing constraints on the early evolution of the northwest Himalayan belt. Several isotopic systems have been used to date the eclogitization and the exhumation of the Tso Morari unit: Lu-Hf, Sm-Nd, Rb-Sr, and Ar-Ar. A ca. 55 Ma age for the eclogitization has been obtained by Lu-Hf on garnet, omphacite, and whole rock from mafic eclogite and by Sm-Nd on garnet, glaucophane, and whole rock from high-pressure metapelites. These results agree with a previously reported U-Pb age on allanite, and together these ages constrain the subduction of the Indian continental margin at the Paleocene-Eocene boundary. During exhumation, the Tso Morari rocks underwent thermal relaxation at about 9 ± 3 kbar, characterized by partial recrystallization under amphibolite facies conditions ca. 47 Ma, as dated by Sm-Nd on garnet, calcic amphibole, and whole rock from metabasalt, Rb-Sr on phengite, apatite, and whole rock, and Ar-Ar on medium-Si phengite from metapelites. Ar-Ar analyses of biotite and low-Si muscovite from metapelites, which recrystallized at <5 kbar toward the end of the exhumation, show that the Tso Morari unit was at upper crustal levels ca. 30 Ma. These results indicate variable exhumation rates for the Tso Morari unit, beginning with rapid exhumation while the Indian margin subduction was still active, and later proceeding at a slower pace during the crustal thickening associated with the Himalayan collision. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.