Exhumation history and landscape evolution of the Sierra de San Luis (Sierras Pampeanas, Argentina) - new insights from low - temperature thermochronological data

ABSTRACT This paper presents low-temperature thermochronological data and K-Ar fault gouge ages from the Sierra de San Luis in the Eastern Sierras Pampeanas in order to constrain its low-temperature thermal evolution and exhumation history. Thermal modelling based on (U-Th)/He dating of apatite and...

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Autores principales:	Bense,Frithjof, Costa,Carlos, Oriolo,Sebastián, Löbens,Stefan, Dunkl,István, Wemmer,Klaus, Siegesmund,Siegfried
Lenguaje:	English
Publicado:	Servicio Nacional de Geología y Minería (SERNAGEOMIN) 2017
Materias:	Sierras Pampeanas Sierra de San Luis K-Ar dating Fault gouge Illite dating Polytype quantification Thermochronology Helium dating Fission track
Acceso en línea:	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-71062017000300275
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spelling	oai:scielo:S0718-710620170003002752017-10-16Exhumation history and landscape evolution of the Sierra de San Luis (Sierras Pampeanas, Argentina) - new insights from low - temperature thermochronological dataBense,FrithjofCosta,CarlosOriolo,SebastiánLöbens,StefanDunkl,IstvánWemmer,KlausSiegesmund,Siegfried Sierras Pampeanas Sierra de San Luis K-Ar dating Fault gouge Illite dating Polytype quantification Thermochronology Helium dating Fission track ABSTRACT This paper presents low-temperature thermochronological data and K-Ar fault gouge ages from the Sierra de San Luis in the Eastern Sierras Pampeanas in order to constrain its low-temperature thermal evolution and exhumation history. Thermal modelling based on (U-Th)/He dating of apatite and zircon and apatite fission track dating point to the Middle Permian and the Triassic/Early Jurassic as main cooling/exhumation phases, equivalent to ca. 40-50% of the total exhumation recorded by the applied methods. Cooling rates are generally low to moderate, varying between 2-10 °C/Ma during the Permian and Triassic periods and 0.5-1.5 °C/Ma in post-Triassic times. Slow cooling and, thus, persistent residence of samples in partial retention/partial annealing temperature conditions strongly influenced obtained ages. Thermochronological data indicate no significant exhumation after Cretaceous times, suggesting that sampled rocks were already at or near surface by the Cretaceous or even before. As consequence, Cenozoic cooling rates are low, generally between 0.2-0.5 °C/Ma which is, depending on geothermal gradient used for calculation, equivalent to a total Cenozoic exhumation of 0.6-1.8 km. K-Ar fault gouge data reveal long-term brittle fault activity. Fault gouge ages constrain the end of ductile and onset of brittle deformation in the Sierra de San Luis to the Late Carboniferous/Early Permian. Youngest K-Ar illite ages of 222-172 Ma are interpreted to represent the last illite formation event, although fault activity is recorded up to the Holocene.info:eu-repo/semantics/openAccessServicio Nacional de Geología y Minería (SERNAGEOMIN)Andean geology v.44 n.3 20172017-09-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-71062017000300275en10.5027/andgeov44n3-a03
institution	Scielo Chile
collection	Scielo Chile
language	English
topic	Sierras Pampeanas Sierra de San Luis K-Ar dating Fault gouge Illite dating Polytype quantification Thermochronology Helium dating Fission track
spellingShingle	Sierras Pampeanas Sierra de San Luis K-Ar dating Fault gouge Illite dating Polytype quantification Thermochronology Helium dating Fission track Bense,Frithjof Costa,Carlos Oriolo,Sebastián Löbens,Stefan Dunkl,István Wemmer,Klaus Siegesmund,Siegfried Exhumation history and landscape evolution of the Sierra de San Luis (Sierras Pampeanas, Argentina) - new insights from low - temperature thermochronological data
description	ABSTRACT This paper presents low-temperature thermochronological data and K-Ar fault gouge ages from the Sierra de San Luis in the Eastern Sierras Pampeanas in order to constrain its low-temperature thermal evolution and exhumation history. Thermal modelling based on (U-Th)/He dating of apatite and zircon and apatite fission track dating point to the Middle Permian and the Triassic/Early Jurassic as main cooling/exhumation phases, equivalent to ca. 40-50% of the total exhumation recorded by the applied methods. Cooling rates are generally low to moderate, varying between 2-10 °C/Ma during the Permian and Triassic periods and 0.5-1.5 °C/Ma in post-Triassic times. Slow cooling and, thus, persistent residence of samples in partial retention/partial annealing temperature conditions strongly influenced obtained ages. Thermochronological data indicate no significant exhumation after Cretaceous times, suggesting that sampled rocks were already at or near surface by the Cretaceous or even before. As consequence, Cenozoic cooling rates are low, generally between 0.2-0.5 °C/Ma which is, depending on geothermal gradient used for calculation, equivalent to a total Cenozoic exhumation of 0.6-1.8 km. K-Ar fault gouge data reveal long-term brittle fault activity. Fault gouge ages constrain the end of ductile and onset of brittle deformation in the Sierra de San Luis to the Late Carboniferous/Early Permian. Youngest K-Ar illite ages of 222-172 Ma are interpreted to represent the last illite formation event, although fault activity is recorded up to the Holocene.
author	Bense,Frithjof Costa,Carlos Oriolo,Sebastián Löbens,Stefan Dunkl,István Wemmer,Klaus Siegesmund,Siegfried
author_facet	Bense,Frithjof Costa,Carlos Oriolo,Sebastián Löbens,Stefan Dunkl,István Wemmer,Klaus Siegesmund,Siegfried
author_sort	Bense,Frithjof
title	Exhumation history and landscape evolution of the Sierra de San Luis (Sierras Pampeanas, Argentina) - new insights from low - temperature thermochronological data
title_short	Exhumation history and landscape evolution of the Sierra de San Luis (Sierras Pampeanas, Argentina) - new insights from low - temperature thermochronological data
title_full	Exhumation history and landscape evolution of the Sierra de San Luis (Sierras Pampeanas, Argentina) - new insights from low - temperature thermochronological data
title_fullStr	Exhumation history and landscape evolution of the Sierra de San Luis (Sierras Pampeanas, Argentina) - new insights from low - temperature thermochronological data
title_full_unstemmed	Exhumation history and landscape evolution of the Sierra de San Luis (Sierras Pampeanas, Argentina) - new insights from low - temperature thermochronological data
title_sort	exhumation history and landscape evolution of the sierra de san luis (sierras pampeanas, argentina) - new insights from low - temperature thermochronological data
publisher	Servicio Nacional de Geología y Minería (SERNAGEOMIN)
publishDate	2017
url	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-71062017000300275
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_version_	1714205855701794816

Exhumation history and landscape evolution of the Sierra de San Luis (Sierras Pampeanas, Argentina) - new insights from low - temperature thermochronological data

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