Retroarc deformation and exhumation near the end of the Andes, southern Patagonia

Julie C. Fosdick, Marty Grove, Jeremy K. Hourigan, Mauricio Calderón

Resultado de la investigación: Article

28 Citas (Scopus)

Resumen

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. 22Ma, long-term exhumation rates have been highest across the western and central thrust domains (0.22-0.37mmyr-1), and significantly lower along the eastern thrust front (0.10-0.17mmyr-1). Since ~7Ma, apatite results from these same regions suggest comparable and slightly higher denudation rates (0.14-0.46mmyr-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 <7-4Ma 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.

Idioma originalEnglish
Páginas (desde-hasta)504-517
Número de páginas14
PublicaciónEarth and Planetary Science Letters
Volumen361
DOI
EstadoPublished - 1 ene 2013

Huella dactilar

Apatites
exhumation
thrust
denudation
apatites
Volcanic rocks
Sedimentary rocks
Miocene
apatite
Tectonics
zircon
Sedimentation
Erosion
Moisture
glaciation
Rocks
rocks
Cooling
sedimentary rocks
monocline

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

Citar esto

Fosdick, Julie C. ; Grove, Marty ; Hourigan, Jeremy K. ; Calderón, Mauricio. / Retroarc deformation and exhumation near the end of the Andes, southern Patagonia. En: Earth and Planetary Science Letters. 2013 ; Vol. 361. pp. 504-517.
@article{854e203c53ce4f3da846efcfc4d95a32,
title = "Retroarc deformation and exhumation near the end of the Andes, southern Patagonia",
abstract = "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. 22Ma, long-term exhumation rates have been highest across the western and central thrust domains (0.22-0.37mmyr-1), and significantly lower along the eastern thrust front (0.10-0.17mmyr-1). Since ~7Ma, apatite results from these same regions suggest comparable and slightly higher denudation rates (0.14-0.46mmyr-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 <7-4Ma 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.",
keywords = "(U-Th)/He thermochronology, Climate, Exhumation, Patagonian Andes, Retroarc thrust-belt",
author = "Fosdick, {Julie C.} and Marty Grove and Hourigan, {Jeremy K.} and Mauricio Calder{\'o}n",
year = "2013",
month = "1",
day = "1",
doi = "10.1016/j.epsl.2012.12.007",
language = "English",
volume = "361",
pages = "504--517",
journal = "Earth and Planetary Science Letters",
issn = "0012-821X",
publisher = "Elsevier",

}

Retroarc deformation and exhumation near the end of the Andes, southern Patagonia. / Fosdick, Julie C.; Grove, Marty; Hourigan, Jeremy K.; Calderón, Mauricio.

En: Earth and Planetary Science Letters, Vol. 361, 01.01.2013, p. 504-517.

Resultado de la investigación: Article

TY - JOUR

T1 - Retroarc deformation and exhumation near the end of the Andes, southern Patagonia

AU - Fosdick, Julie C.

AU - Grove, Marty

AU - Hourigan, Jeremy K.

AU - Calderón, Mauricio

PY - 2013/1/1

Y1 - 2013/1/1

N2 - 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. 22Ma, long-term exhumation rates have been highest across the western and central thrust domains (0.22-0.37mmyr-1), and significantly lower along the eastern thrust front (0.10-0.17mmyr-1). Since ~7Ma, apatite results from these same regions suggest comparable and slightly higher denudation rates (0.14-0.46mmyr-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 <7-4Ma 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.

AB - 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. 22Ma, long-term exhumation rates have been highest across the western and central thrust domains (0.22-0.37mmyr-1), and significantly lower along the eastern thrust front (0.10-0.17mmyr-1). Since ~7Ma, apatite results from these same regions suggest comparable and slightly higher denudation rates (0.14-0.46mmyr-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 <7-4Ma 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.

KW - (U-Th)/He thermochronology

KW - Climate

KW - Exhumation

KW - Patagonian Andes

KW - Retroarc thrust-belt

UR - http://www.scopus.com/inward/record.url?scp=84872278872&partnerID=8YFLogxK

U2 - 10.1016/j.epsl.2012.12.007

DO - 10.1016/j.epsl.2012.12.007

M3 - Article

AN - SCOPUS:84872278872

VL - 361

SP - 504

EP - 517

JO - Earth and Planetary Science Letters

JF - Earth and Planetary Science Letters

SN - 0012-821X

ER -