Retroarc deformation and exhumation near the end of the Andes, southern Patagonia
Artículo de publicación ISI The southern Patagonian Andes constitute the narrow, high-latitude end of the Andean orogen belt in South America, where inherited basin paleogeography, subduction processes, retroarc crustal thickening, and late Cenozoic glaciation have collectively influenced their unus...
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ftunivchile:oai:repositorio.uchile.cl:2250/126447 2023-05-15T18:16:02+02:00 Retroarc deformation and exhumation near the end of the Andes, southern Patagonia Fosdick, Julie C. Grove, Marty Hourigan, JeremyK. Calderón, Mauricio 2013 http://repositorio.uchile.cl/handle/2250/126447 en eng Elsevier Earth and Planetary ScienceLetters 361 (2013) 504–517 doi 10.1016/j.epsl.2012.12.007 http://repositorio.uchile.cl/handle/2250/126447 Attribution-NonCommercial-NoDerivs 3.0 Chile http://creativecommons.org/licenses/by-nc-nd/3.0/cl/ CC-BY-NC-ND Patagonian Andes Artículo de revista 2013 ftunivchile 2021-05-29T23:48:47Z Artículo de publicación ISI The southern Patagonian Andes constitute the narrow, high-latitude end of the Andean orogen belt in South America, where inherited basin paleogeography, subduction processes, retroarc crustal thickening, and late Cenozoic glaciation have collectively influenced their unusual tectonic and physiographic evolution. New zircon and apatite (U–Th)/He thermochronology from the Patagonian Andes between 50°30′ and 51°30′S suggest concentrated exhumation across the retroarc (leeward) side of the orogen since early Miocene time. Zircon (U–Th)/He (ZHe) ages range from 44 to 10 Ma; oldest ages are recorded in the Patagonian batholith and along the far eastern frontal foreland monocline. Regionally-uniform ZHe ages between 22 and 18 Ma, located across a ∼75 km wide-zone of the Patagonian retroarc thrust-belt indicate widespread early Miocene cooling through the ZHe partial retention zone. Mesozoic sedimentary and volcanic rocks in this region have been exhumed from at least 5 to 6 km depths. Early Miocene denudation of the thrust-belt, deformation, and increased foreland sedimentation rates coincided with opening of the Scotia Sea, suggesting a causal response of the foreland to changes in plate dynamics. The apatite (U–Th)/He (AHe) ages from a similar region range from 11 to 3 Ma; the youngest ages (6–3 Ma) are spatially clustered within the more deeply-exhumed central thrust domain. We interpret these AHe ages to record >1–2 km of erosional denudation associated with late Cenozoic glaciation and fluvioglacial processes in Patagonia beginning ca. 7 Ma. Zircon results indicate that since ca. 22 Ma, long-term exhumation rates have been highest across the western and central thrust domains (0.22–0.37 mm yr−1), and significantly lower along the eastern thrust front (0.10–0.17 mm yr−1). Since ∼7 Ma, apatite results from these same regions suggest comparable and slightly higher denudation rates (0.14–0.46 mm yr−1), particularly within the eastern thrust domain, consistent with efficient erosional processes acting in the retroarc region. These results from the Patagonian retroarc region, particularly the predominance of <7–4 Ma AHe ages, provide a new understanding for regional orogenic erosion models that are largely based on existing data from the windward regions. We suggest that retroarc denudation was enhanced by widespread Miocene structural uplift and unroofing of the fine-grained siliciclastic rocks of the marine Cretaceous Magallanes/Austral foreland basin. Furthermore, its location at the southern tip of the orogen, may have allowed additional moisture to reach the leeward side, leading to sustained late Cenozoic erosional denudation. Article in Journal/Newspaper Scotia Sea Universidad de Chile: Repositorio académico Austral Isi ENVELOPE(-38.550,-38.550,65.617,65.617) Magallanes ENVELOPE(-62.933,-62.933,-64.883,-64.883) Patagonia Scotia Sea |
institution |
Open Polar |
collection |
Universidad de Chile: Repositorio académico |
op_collection_id |
ftunivchile |
language |
English |
topic |
Patagonian Andes |
spellingShingle |
Patagonian Andes Fosdick, Julie C. Grove, Marty Hourigan, JeremyK. Calderón, Mauricio Retroarc deformation and exhumation near the end of the Andes, southern Patagonia |
topic_facet |
Patagonian Andes |
description |
Artículo de publicación ISI The southern Patagonian Andes constitute the narrow, high-latitude end of the Andean orogen belt in South America, where inherited basin paleogeography, subduction processes, retroarc crustal thickening, and late Cenozoic glaciation have collectively influenced their unusual tectonic and physiographic evolution. New zircon and apatite (U–Th)/He thermochronology from the Patagonian Andes between 50°30′ and 51°30′S suggest concentrated exhumation across the retroarc (leeward) side of the orogen since early Miocene time. Zircon (U–Th)/He (ZHe) ages range from 44 to 10 Ma; oldest ages are recorded in the Patagonian batholith and along the far eastern frontal foreland monocline. Regionally-uniform ZHe ages between 22 and 18 Ma, located across a ∼75 km wide-zone of the Patagonian retroarc thrust-belt indicate widespread early Miocene cooling through the ZHe partial retention zone. Mesozoic sedimentary and volcanic rocks in this region have been exhumed from at least 5 to 6 km depths. Early Miocene denudation of the thrust-belt, deformation, and increased foreland sedimentation rates coincided with opening of the Scotia Sea, suggesting a causal response of the foreland to changes in plate dynamics. The apatite (U–Th)/He (AHe) ages from a similar region range from 11 to 3 Ma; the youngest ages (6–3 Ma) are spatially clustered within the more deeply-exhumed central thrust domain. We interpret these AHe ages to record >1–2 km of erosional denudation associated with late Cenozoic glaciation and fluvioglacial processes in Patagonia beginning ca. 7 Ma. Zircon results indicate that since ca. 22 Ma, long-term exhumation rates have been highest across the western and central thrust domains (0.22–0.37 mm yr−1), and significantly lower along the eastern thrust front (0.10–0.17 mm yr−1). Since ∼7 Ma, apatite results from these same regions suggest comparable and slightly higher denudation rates (0.14–0.46 mm yr−1), particularly within the eastern thrust domain, consistent with efficient erosional processes acting in the retroarc region. These results from the Patagonian retroarc region, particularly the predominance of <7–4 Ma AHe ages, provide a new understanding for regional orogenic erosion models that are largely based on existing data from the windward regions. We suggest that retroarc denudation was enhanced by widespread Miocene structural uplift and unroofing of the fine-grained siliciclastic rocks of the marine Cretaceous Magallanes/Austral foreland basin. Furthermore, its location at the southern tip of the orogen, may have allowed additional moisture to reach the leeward side, leading to sustained late Cenozoic erosional denudation. |
format |
Article in Journal/Newspaper |
author |
Fosdick, Julie C. Grove, Marty Hourigan, JeremyK. Calderón, Mauricio |
author_facet |
Fosdick, Julie C. Grove, Marty Hourigan, JeremyK. Calderón, Mauricio |
author_sort |
Fosdick, Julie C. |
title |
Retroarc deformation and exhumation near the end of the Andes, southern Patagonia |
title_short |
Retroarc deformation and exhumation near the end of the Andes, southern Patagonia |
title_full |
Retroarc deformation and exhumation near the end of the Andes, southern Patagonia |
title_fullStr |
Retroarc deformation and exhumation near the end of the Andes, southern Patagonia |
title_full_unstemmed |
Retroarc deformation and exhumation near the end of the Andes, southern Patagonia |
title_sort |
retroarc deformation and exhumation near the end of the andes, southern patagonia |
publisher |
Elsevier |
publishDate |
2013 |
url |
http://repositorio.uchile.cl/handle/2250/126447 |
long_lat |
ENVELOPE(-38.550,-38.550,65.617,65.617) ENVELOPE(-62.933,-62.933,-64.883,-64.883) |
geographic |
Austral Isi Magallanes Patagonia Scotia Sea |
geographic_facet |
Austral Isi Magallanes Patagonia Scotia Sea |
genre |
Scotia Sea |
genre_facet |
Scotia Sea |
op_relation |
Earth and Planetary ScienceLetters 361 (2013) 504–517 doi 10.1016/j.epsl.2012.12.007 http://repositorio.uchile.cl/handle/2250/126447 |
op_rights |
Attribution-NonCommercial-NoDerivs 3.0 Chile http://creativecommons.org/licenses/by-nc-nd/3.0/cl/ |
op_rightsnorm |
CC-BY-NC-ND |
_version_ |
1766189441538326528 |