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Reconstructing the Late Paleozoic : Early Mesozoic plutonic and sedimentary record of south-east Peru : Orphaned back-arcs along the western margin of Gondwana

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Defense Thèse de doctorat : Univ. Genève, 2012 - Sc. 4459 - 2012/05/22
Collection Terre et Environnement; 111
Abstract This thesis investigates the sedimentary, plutonic and tectonic evolution of the Eastern Cordillera region of south-east Peru during assembly of the Pangea supercontinent and subsequent early pulses of break-up. We present a chronostratigraphic framework for the Carboniferous to Triassic sedimentary and plutonic record using geochronological, geochemical and isotopic methods, integrated with field observations. The first chapter investigates the plutonic record and its relation to growth of the continental crust. With U-Pb zircon dating we demonstrate that magmatism was intermittently active over a period of nearly half a billion years and can be separated into six magmatic pulses with a duration of 20 myr or less ranging from the Ordovician to the Miocene. The plutons were mainly emplaced in a back-arc setting where magmatism was generated by remelting of pre-existing crust. The second chapter presents sedimentological, geochronological and geochemical data acquired from the sedimentary and volcanic rocks of the Mitu Group, demonstrating that the Mitu Group was deposited in the Middle to Upper Triassic in an extensional basin with a large simple shear component, most likely in a back-arc setting. The third chapter introduces the first chronostratigraphic framework for the Carboniferous – Early Permian period in Peru based on radio-isotopic dates on volcanic and detrital samples. The model serves to reconstruct the paleogeographic and tectonic history of Peru as it formed part of the western Gondwana margin during assembly and suturing of the Pangea supercontinent.
Keywords PeruU-Pb zirconHfbasin reconstructioncrustal growthpaleogeographydetrital zirconMitu GroupAmbo GroupCopacabana Groupback-arc basin
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URN: urn:nbn:ch:unige-230955
Note résumé en Francais (4 pages)
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REITSMA, Martje Jel. Reconstructing the Late Paleozoic : Early Mesozoic plutonic and sedimentary record of south-east Peru : Orphaned back-arcs along the western margin of Gondwana. Université de Genève. Thèse, 2012. https://archive-ouverte.unige.ch/unige:23095

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Deposited on : 2012-10-01

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