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| DOI | 10.5027/ANDGEOV44N3-A03 | ||||||
| Año | 2017 | ||||||
| Tipo | artículo de investigación |
Citas Totales
Autores Afiliación Chile
Instituciones Chile
% Participación
Internacional
Autores
Afiliación Extranjera
Instituciones
Extranjeras
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 degrees C/Ma during the Permian and Triassic periods and 0.5-1.5 degrees 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 degrees 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.
| Ord. | Autor | Género | Institución - País |
|---|---|---|---|
| Löbens, Stefan | Hombre |
University of Göttingen - Alemania
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| 1 | Bense, Frithjof | Hombre |
UNIV GOTTINGEN - Alemania
Fed Inst Geosci & Nat Resources - Alemania University of Göttingen - Alemania Federal Institute for Geosciences and Natural Resources - Alemania |
| 2 | Costa, Carlos | Hombre |
UNIV NACL SAN LUIS - Argentina
Universidad Nacional de San Luis - Argentina |
| 3 | Oriolo, Sebastian | Hombre |
UNIV GOTTINGEN - Alemania
University of Göttingen - Alemania |
| 4 | Loebens, Stefan | Hombre |
UNIV GOTTINGEN - Alemania
University of Göttingen - Alemania |
| 5 | Dunkl, István | Hombre |
UNIV GOTTINGEN - Alemania
University of Göttingen - Alemania |
| 6 | Wemmer, Klaus | Hombre |
UNIV GOTTINGEN - Alemania
University of Göttingen - Alemania |
| 7 | Siegesmund, Siegfried | Hombre |
UNIV GOTTINGEN - Alemania
University of Göttingen - Alemania |
| Agradecimiento |
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| This research project is financed by the German Science Foundation (DFG project SI 438/31-1). The authors gratefully thank the constructive review by L. Giambiagi. We are also grateful for the careful sample preparation made by A. Sussenberger and the help of E. Ahumada and M. Lopez de Luchi, alleviating the stay in Argentina, as well as A. Steenken and J.A. Palavecino assisting in the field. Field work done by F. Bense was financially supported by the DAAD (project number D/08/48018). |