Successive deformation episodes along the Lungmu Co zone, west-central Tibet |
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| Authors: | PH Leloup NO ArnaudG Mahéo JL PaquetteS Guillot F ValliH Li Z XuR Lacassin P Tapponnier |
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| Institution: | a Laboratoire de Géologie de Lyon: Terre, Planètes et Environnement, UMR CNRS 5276, Université Claude Bernard - Ecole normale supérieure de lyon, 2 rue Raphaël Dubois, 69622 Villeurbanne, Franceb ISTEEM-UM2, Géosciences Montpellier, UMR CNRS 5243, Université des sciences et techniques du Languedoc, 4095 Montpellier cedex 5, Francec Laboratoire Magmas et Volcans, UMR CNRS 6524, Observatoire de Physique du globe de Clermont-Ferrand, 63038 Clermont-Ferrand, Franced ISTerre, CNRS, University of Grenoble I, BP 53, 1381 rue de la Piscine, 38041 Grenoble cedex 9, Francee Equipe de Tectonique, Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Univ Paris Diderot, UMR 7154 CNRS, F-75005 Paris, Francef Institute of Geology, CAGS, 26 Baiwanzhuang Road, Beijing 100037, China |
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| Abstract: | Field study, thermochronology and geochemistry of the east Lungmu Co (LMC) range highlight some of the geological events that shaped western Tibet. The LMC fault zone has long been interpreted as the boundary between the Tianshuihai terrane of Laurasian affinity and the Qiangtang block of Gondwanian affinity. In the LMC range, the Paleozoic series is intruded by the Mangtsa leucogranite whose zircon have a U/Pb age of 116.9 ± 1 Ma and by mafic rocks with U/Pb zircon ages ranging from 116.9 ± 1 to 95.1 ± 1.7 Ma. Geochemistry of the mafic rocks indicates that they have been emplaced in a supra-subduction zone setting, probably the north dipping Nujiang suture zone. 40Ar/39Ar micas ages of the granite indicate that cooling below ~ 350 °C occurred between 105 and 85 Ma. 40Ar/39Ar K-feldspar data suggest a fast cooling event at 60-55 Ma, which we relate to the reactivation of the LMC suture zone as a thrust at the onset of the India-Eurasia collision. The last, and still active, deformation event corresponds to left-lateral strike-slip faulting along the ENE-WSW LMC fault. |
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| Keywords: | Tibet Tectonics Suture zone Thermochronology Geochemistry |
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