Influence of the ridge subduction on the overriding plate dynamics: example of the Nazca ridge and the Amazonian basin

• Main Author: Espurt, Nicolas
• Other Authors: Laboratoire des Mécanismes et Transfert en Géologie (LMTG), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales Toulouse (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Université Paul Sabatier - Toulouse III, Patrice BABY, Stéphane BRUSSET
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2007
• Subjects: Nazca Ridge; Amazonian basin; Flat subduction; Low-temperature thermochronology; Balanced cross-sections; Analogue models; Subandean; Peru; Coupes équilibrées; Subduction horizontale; Thermochronologie basse température; Bassin amazonien; Ride de Nazca; Modélisations analogiques; Subandin; Pérou; [SDU.STU.AG]Sciences of the Universe [physics]/Earth Sciences/Applied geology; South Atlantic Ocean
• Online Access: https://tel.archives-ouvertes.fr/tel-00204692; https://tel.archives-ouvertes.fr/tel-00204692/document; https://tel.archives-ouvertes.fr/tel-00204692/file/These_complete_N._ESPURT.pdf

The Nazca ridge subduction is recorded in the eastern side of the Peruvian Andes. Its topographic response is the Fitzcarrald Arch, which induces the foredeep-foreslope-foredeep N-S partitioning of the Amazonian foreland system. Using lithospheric analogue models we evidence that horizontal subduction: i) requires the subduction of hundreds of kilometers of buoyant oceanic plateau; ii) increases the interplate friction and iii) induces uplift in the retro-lithosphere as a consequence of shortening and ridge underplating. In the Fitzcarrald Arch, the structural framework consists of two superimposed thrust-wedges. The lower wedge consists in the reactivation of a carboniferous thrust-wedge. The upper wedge is deformed by thin-skinned thrust tectonics. The structural evolution is controlled by the thickness of the paleozoic sedimentary pile involved in the thrust system. It is marked by a transfer-zone located at the northern border of a paleozoic basin. Apatite fission track analysis (AFT) allows us to determine an exhumation stage around 110 Ma linked to the opening of the South Atlantic Ocean. Since ~6Ma, AFT recorded the thrust propagation in the Camisea South of the transfer zone, where apatite thermochronometers have been reset. However, the underplating of the Nazca ridge had no influence on the short wavelength deformation of the Subandes. Les signatures de la subduction de la ride de Nazca s'expriment sur le flanc est des Andes péruviennes: l'Arche de Fitzcarrald en est la réponse topographique dans le bassin d'avant-pays amazonien. La subduction horizontale de la ride de Nazca perturbe la flexion de la lithosphère sud-américaine depuis ~4 Ma. Ce soulèvement est responsable de la configuration N-S actuelle, foredeep-foreslope-foredeep, du bassin amazonien. L'élaboration de modèles analogiques lithosphériques adaptés au contexte régional de l'étude a permis de comprendre les effets de la subduction d'un plateau océanique sur la plaque continentale chevauchante: i) le processus de la subduction ...