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Reconstructing north-western Gondwana with implications for the evolution of the Iapetus and Rheic Oceans: a geochronological, thermochronological and geochemical study |
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Defense | Thèse de doctorat : Univ. Genève, 2013 - Sc. 4581 - 2013/05/27 | |
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Terre et Environnement; 121 |
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Abstract | This thesis investigates the tectonic histories of igneous and metamorphic rocks exposed in the Mérida Andes, Venezuela, and Santander Massif, Colombia from the Late Cambrian to the present day. Zircon U-Pb ages from 52 igneous and metamorphic rocks constrain the main periods of arc magmatism on the north-western corner of Gondwana from ~500 to ~413 Ma and from ~294 Ma to ~196 Ma. Peak Barrovian metamorphic conditions are recorded by anatexis at ~477 Ma and the intrusion of synkinematic granitoids until ~472 Ma. Back-arc extension is recorded at ~453 Ma. High exhumation rates constrained by 40Ar/39Ar and apatite U-Pb data suggest a second orogenic phase at ~250 Ma. Combined isotopic data show that the basement rocks of the studied regions are autochthonous to north-western Gondwana, and that arc magmatism sampled more juvenile sources during extension than during orogenesis. Low temperature thermochronology suggests that the Santander Massif started exhuming at ~40 Ma. | |
Keywords | Tectonics — Geochronology — Thermochronology — Isotope geochemistry — Orogenesis — Venezuela — Colombia — Andes — Precambrian — Palaeozoic — Ordovician — Silurian — Permian — Triassic — Jurassic — Exhumation — Granite — Barrovian metamorphism — Granulite — Gondwana — Mérida — Santander — Fission track — Hf — Crustal growth | |
Identifiers | URN: urn:nbn:ch:unige-316537 | |
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Research group | Isotope Geochemistry and Geochronology | |
Project | Swiss National Science Foundation: 200021_129497 | |
Citation (ISO format) | VAN DER LELIJ, Roelant. Reconstructing north-western Gondwana with implications for the evolution of the Iapetus and Rheic Oceans: a geochronological, thermochronological and geochemical study. Université de Genève. Thèse, 2013. doi: 10.13097/archive-ouverte/unige:31653 https://archive-ouverte.unige.ch/unige:31653 |