Tectonic Evolution of the Patagonian Orocline: New Insights from a Paleomagnetic Study in Southernmost America
International audience One of the most noteworthy features of the Southern Andes is its bend, where the orogenic trend and main tectonic provinces change from Andean N-S oriented structures to W-E orientations in Tierra del Fuego. Few paleomagnetic studies have been carried out, and whether the bend...
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ftunivrennes2hal:oai:HAL:insu-01265807v1 2024-02-11T09:57:13+01:00 Tectonic Evolution of the Patagonian Orocline: New Insights from a Paleomagnetic Study in Southernmost America Poblete, Fernando Roperch, Pierrick Arriagada, Cesar Ramírez de Arellano, Cristobal Departamento de Geologia Facultad de Ciencias Fisicas y Matemáticas-Universidad de Chile Géosciences Rennes (GR) Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR) Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS) Carrera de Geología Universidad Andrés Bello Santiago (UNAB) American Geophysical Union San Francisco, United States 2015-12-14 https://insu.hal.science/insu-01265807 en eng HAL CCSD insu-01265807 https://insu.hal.science/insu-01265807 AGU Fall Meeting 2015 https://insu.hal.science/insu-01265807 AGU Fall Meeting 2015, Dec 2015, San Francisco, United States. pp.T23A-2905, 2015 [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] info:eu-repo/semantics/conferenceObject Conference poster 2015 ftunivrennes2hal 2024-01-23T23:52:43Z International audience One of the most noteworthy features of the Southern Andes is its bend, where the orogenic trend and main tectonic provinces change from Andean N-S oriented structures to W-E orientations in Tierra del Fuego. Few paleomagnetic studies have been carried out, and whether the bending is a primary curvature or a true orocline is still matter of controversy; also the mechanism of its formation. We have conducted a paleomagnetic study between 50°S to ~56°S, where 146 sites were drilled. Paleomagnetic data were obtained in 44 sites. Results in Early Cretaceous sediments and volcanics rocks confirm a remagnetization event during the mid-Cretaceous and record ~90° of counterclockwise rotation. Paleomagnetic results in mid-Cretaceous intrusives rocks record large counterclockwise rotation (>90°) while Late Cretaceous-Early Eocene intrusive rocks only record ~45° to ~30°. The paleomagnetic results reveal a systematic pattern of rotation—the Fueguian rotation pattern—suggesting that the curvature of Patagonia would have occurred in two stages: the first stage during the collapse and obduction of the Rocas Verdes basin in the mid-Cretaceous and a second stage between the Late Cretaceous and the Paleocene, concomitant with exhumation of Cordillera Darwin and propagation of the fold and thrust belt into the Magallanes foreland. Integrating this result in plate reconstructions shows the Antarctic Peninsula as a prolongation of Patagonia and would have acted as a non-rotational rigid block, facilitating the development of the Patagonia Bend. This land bridge could be a dispersal mechanism for fauna between Australia and South America and would have restricted deep ocean water circulation. Conference Object Antarc* Antarctic Antarctic Peninsula Tierra del Fuego Archive Ouverte de l'Université Rennes (HAL) Antarctic Antarctic Peninsula Magallanes ENVELOPE(-62.933,-62.933,-64.883,-64.883) Patagonia Rocas ENVELOPE(-56.948,-56.948,-63.398,-63.398) The Antarctic |
institution |
Open Polar |
collection |
Archive Ouverte de l'Université Rennes (HAL) |
op_collection_id |
ftunivrennes2hal |
language |
English |
topic |
[SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] |
spellingShingle |
[SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] Poblete, Fernando Roperch, Pierrick Arriagada, Cesar Ramírez de Arellano, Cristobal Tectonic Evolution of the Patagonian Orocline: New Insights from a Paleomagnetic Study in Southernmost America |
topic_facet |
[SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] |
description |
International audience One of the most noteworthy features of the Southern Andes is its bend, where the orogenic trend and main tectonic provinces change from Andean N-S oriented structures to W-E orientations in Tierra del Fuego. Few paleomagnetic studies have been carried out, and whether the bending is a primary curvature or a true orocline is still matter of controversy; also the mechanism of its formation. We have conducted a paleomagnetic study between 50°S to ~56°S, where 146 sites were drilled. Paleomagnetic data were obtained in 44 sites. Results in Early Cretaceous sediments and volcanics rocks confirm a remagnetization event during the mid-Cretaceous and record ~90° of counterclockwise rotation. Paleomagnetic results in mid-Cretaceous intrusives rocks record large counterclockwise rotation (>90°) while Late Cretaceous-Early Eocene intrusive rocks only record ~45° to ~30°. The paleomagnetic results reveal a systematic pattern of rotation—the Fueguian rotation pattern—suggesting that the curvature of Patagonia would have occurred in two stages: the first stage during the collapse and obduction of the Rocas Verdes basin in the mid-Cretaceous and a second stage between the Late Cretaceous and the Paleocene, concomitant with exhumation of Cordillera Darwin and propagation of the fold and thrust belt into the Magallanes foreland. Integrating this result in plate reconstructions shows the Antarctic Peninsula as a prolongation of Patagonia and would have acted as a non-rotational rigid block, facilitating the development of the Patagonia Bend. This land bridge could be a dispersal mechanism for fauna between Australia and South America and would have restricted deep ocean water circulation. |
author2 |
Departamento de Geologia Facultad de Ciencias Fisicas y Matemáticas-Universidad de Chile Géosciences Rennes (GR) Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR) Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS) Carrera de Geología Universidad Andrés Bello Santiago (UNAB) American Geophysical Union |
format |
Conference Object |
author |
Poblete, Fernando Roperch, Pierrick Arriagada, Cesar Ramírez de Arellano, Cristobal |
author_facet |
Poblete, Fernando Roperch, Pierrick Arriagada, Cesar Ramírez de Arellano, Cristobal |
author_sort |
Poblete, Fernando |
title |
Tectonic Evolution of the Patagonian Orocline: New Insights from a Paleomagnetic Study in Southernmost America |
title_short |
Tectonic Evolution of the Patagonian Orocline: New Insights from a Paleomagnetic Study in Southernmost America |
title_full |
Tectonic Evolution of the Patagonian Orocline: New Insights from a Paleomagnetic Study in Southernmost America |
title_fullStr |
Tectonic Evolution of the Patagonian Orocline: New Insights from a Paleomagnetic Study in Southernmost America |
title_full_unstemmed |
Tectonic Evolution of the Patagonian Orocline: New Insights from a Paleomagnetic Study in Southernmost America |
title_sort |
tectonic evolution of the patagonian orocline: new insights from a paleomagnetic study in southernmost america |
publisher |
HAL CCSD |
publishDate |
2015 |
url |
https://insu.hal.science/insu-01265807 |
op_coverage |
San Francisco, United States |
long_lat |
ENVELOPE(-62.933,-62.933,-64.883,-64.883) ENVELOPE(-56.948,-56.948,-63.398,-63.398) |
geographic |
Antarctic Antarctic Peninsula Magallanes Patagonia Rocas The Antarctic |
geographic_facet |
Antarctic Antarctic Peninsula Magallanes Patagonia Rocas The Antarctic |
genre |
Antarc* Antarctic Antarctic Peninsula Tierra del Fuego |
genre_facet |
Antarc* Antarctic Antarctic Peninsula Tierra del Fuego |
op_source |
AGU Fall Meeting 2015 https://insu.hal.science/insu-01265807 AGU Fall Meeting 2015, Dec 2015, San Francisco, United States. pp.T23A-2905, 2015 |
op_relation |
insu-01265807 https://insu.hal.science/insu-01265807 |
_version_ |
1790609509811486720 |