Calderón, M; Fosdick, J. C.; Warren, C.; Massonne, H.-J.; Fanning, C. M.; Fadel Cury, L.; Schwanethal , J.; Fonseca, P. E.; Galaz, G.; Gaytán, D. and Hervé, F.
|DOI (Digital Object Identifier) Link:||http://doi.org/10.1016/j.tecto.2011.12.034|
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The Canal de las Montañas Shear Zone (CMSZ), southern Patagonian Andes (51–52°S), is a low-grade mylonite belt generated from felsic ignimbritic, pelitic and basaltic protoliths of the Late Jurassic–Early Cretaceous Rocas Verdes basin. The different types of rock fabrics across the CMSZ are thought to be associated with relatively intermediate and high strain conditions, characterized by the development of a narrow western belt of S–C´-type mylonites and phyllonites interpreted as the metamorphic sole thrust of the Sarmiento Ophiolitic Complex. Highly strained rocks of the CMSZ display a reverse, continent-ward tectonic transport, with a minor dextral component of shearing. Transitional pumpellyite–actinolite and upper greenschist facies metamorphic conditions at ca. 5–6 kbar and 230–260 °C indicate that the primary shearing event occurred in a subduction zone setting. In-situ 40Ar/39Ar laserprobe chronology yielded ages of ca. 85 Ma on syntectonic phengite which are interpreted as representing cooling synchronous with mica crystallization during the main compressive deformational event. The 78–81 Ma U–Pb zircon crystallization ages of cross-cutting plutonic and hypabyssal rocks and 40Ar/39Ar amphibole age of ca.79 Ma from lamprophyric dikes within the fold-thrust belt constrain an upper age limit of the ophiolite tectonic emplacement deformation.
|Item Type:||Journal Article|
|Copyright Holders:||2011 Elsevier B.V.|
|Keywords:||Patagonian Andes; Sarmiento Ophiolitic Complex; Rocas Verdes basin; metamorphic sole; geochronology; geothermobarometry|
|Academic Unit/Department:||Faculty of Science, Technology, Engineering and Mathematics (STEM) > Environment, Earth and Ecosystem Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
|Interdisciplinary Research Centre:||Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)|
|Depositing User:||Clare Warren|
|Date Deposited:||31 Jan 2012 10:17|
|Last Modified:||02 Aug 2016 14:11|
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