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Geodynamic and climatic forcing on late-Cenozoic exhumation of the Southern Patagonian Andes (Fitz Roy and Torres del Paine massifs)
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  • Veleda Astarte Paiva Muller,
  • Christian Sue,
  • Pierre Valla,
  • Pietro Sternai,
  • Thibaud Simon-Labric,
  • Cecile Gautheron,
  • Kurt M. Cuffey,
  • Djordje Grujic,
  • Matthias Bernet,
  • Joseph Martinod,
  • Matías C. Ghiglione,
  • Herman Frédéric,
  • Peter W Reiners,
  • David Shuster,
  • Chelsea Willett,
  • Lukas P Baumgartner,
  • Jean Braun
Veleda Astarte Paiva Muller
University of Milano-Bicocca

Corresponding Author:[email protected]

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Christian Sue
Université Grenoble Alpes
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Pierre Valla
Université Grenoble Alpes
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Pietro Sternai
University of Milano-Bicocca
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Thibaud Simon-Labric
Centre de Géologie Oisans Alpes, Musée des Minéraux
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Cecile Gautheron
Université Paris Saclay
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Kurt M. Cuffey
University of California, Berkeley
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Djordje Grujic
Dalhousie University
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Matthias Bernet
Universite Grenoble Alpes
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Joseph Martinod
Université de Savoie Mont Blanc
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Matías C. Ghiglione
Universidad de Buenos Aires - CONICET
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Herman Frédéric
University of Lausanne
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Peter W Reiners
University of Arizona
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David Shuster
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Chelsea Willett
Department of Geography, Department of Earth and Planetary Science, University of California - Berkeley, USA
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Lukas P Baumgartner
Universite de Lausanne
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Jean Braun
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Deep incised glacial valleys surrounded by high peaks form the modern topography of the Southern Patagonian Andes. Two Miocene plutonic complexes in the Andean retroarc, the cores of the Fitz Roy (49°S) and Torres del Paine (51°S) massifs, were emplaced at 16.7±0.3 Ma and 12.5±0.1 Ma, respectively. Subduction of ocean ridge segments initiated at 54°S, generating northward opening of an asthenospheric window with associated mantle upwelling and orogenic shortening since 16 Ma. Subsequently, the onset of major glaciations at 7 Ma caused drastic changes in the regional topographic evolution. To constrain the respective contributions of tectonic convergence, mantle upwelling and fluvio-glacial erosion to rock exhumation, we present inverse thermal modeling of a new dataset of zircon and apatite (U-Th)/He from the two massifs, complemented by apatite 4He/3He data for Torres del Paine. Our results show rapid rock exhumation recorded in the Fitz Roy massif between 10.5 and 9 Ma, which we ascribe to mantle upwelling and/or crustal shortening due to ridge subduction at 49°S. Both massifs record a pulse of rock exhumation between 6.5 and 4.5 Ma, which we interpret as the result of the onset of Patagonian glaciations. After a period of erosional quiescence during the Miocene/Pliocene transition, increased rock exhumation since 3-2 Ma to present day is interpreted as the result of alpine glacial valley carving promoted by reinforced glacial-interglacial cycles. This study demonstrates that along-strike thermochronological studies provide us with the means to assess the spatio-temporal variations in tectonic, mantle, and surface processes forcing on rock exhumation.
05 May 2023Submitted to ESS Open Archive
05 May 2023Published in ESS Open Archive