Geochronology of pediments and marine terraces in north-central Chile and their implications for Quaternary uplift in the Western Andes

María Pía Rodríguez, Sébastien Carretier, Reynaldo Charrier, Marianne Saillard, Vincent Regard, Gérard Hérail, Sarah Hall, Dan Farber, Laurence Audin

Resultado de la investigación: Article

15 Citas (Scopus)

Resumen

In north-central Chile, a wide shore platform is morphologically connected with a high fluvial terrace and a pediment. The eastward extension of Quaternary coastal uplift in the Southern Central Andes is poorly constrained since no age correlation between marine and continental landforms has been reported. We use 26Al and 10Be concentrations to constrain the geomorphic evolution of these marine and continental landforms near the Choapa valley (31.6° S). 10Be ages for the shore platform indicate that this surface was repeatedly reoccupied during sea-level highstands between ~800 and 500ka and uplifted after 500ka. While 'zero erosion' ages for the pediment between ~600 and 300ka only partly overlap the shore platform age range, more realistic exposure ages calculated for an erosion rate of 1m/Ma are between ~945 and 475ka, fitting the age range of the correlated shore platform. 10Be concentrations of the high fluvial terrace are highly scattered evidencing vertical mixing of clasts probably due to slow lowering of the surface. Although it is not possible to determine an age for this landform, the scattering among its 10Be concentrations implies that this marker is several hundreds of thousands of years old and that the high fluvial terrace began to form at ~1200ka or after. Finally, 10Be concentrations of the high fluvial terrace, the pediment and the shore platform are of the same order of magnitude, which is consistent with the clear morphologic correlation between these three types of landforms. These data suggest that the marine and continental landforms studied formed synchronously, with some local differences, during a long period of relative tectonic stability between ~(1200?) 800 and 500ka and uplifted after 500ka. Our results confirm recent studies showing a post-400±100ka renewal of uplift along the Pacific coast after a Lower to Middle Pleistocene period of slow uplift. Moreover, the extension of the surfaces suggests that a broad region of ~40km has been uplifted ca. 150m during the Quaternary.

Idioma originalEnglish
Páginas (desde-hasta)33-46
Número de páginas14
PublicaciónGeomorphology
Volumen180-181
DOI
EstadoPublished - 1 ene 2013

Huella dactilar

pediment
shore platform
geochronology
terrace
uplift
landform
highstand
vertical mixing
erosion rate
clast
scattering
sea level
Pleistocene
erosion
valley
tectonics
coast

ASJC Scopus subject areas

  • Earth-Surface Processes

Citar esto

Rodríguez, María Pía ; Carretier, Sébastien ; Charrier, Reynaldo ; Saillard, Marianne ; Regard, Vincent ; Hérail, Gérard ; Hall, Sarah ; Farber, Dan ; Audin, Laurence. / Geochronology of pediments and marine terraces in north-central Chile and their implications for Quaternary uplift in the Western Andes. En: Geomorphology. 2013 ; Vol. 180-181. pp. 33-46.
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abstract = "In north-central Chile, a wide shore platform is morphologically connected with a high fluvial terrace and a pediment. The eastward extension of Quaternary coastal uplift in the Southern Central Andes is poorly constrained since no age correlation between marine and continental landforms has been reported. We use 26Al and 10Be concentrations to constrain the geomorphic evolution of these marine and continental landforms near the Choapa valley (31.6° S). 10Be ages for the shore platform indicate that this surface was repeatedly reoccupied during sea-level highstands between ~800 and 500ka and uplifted after 500ka. While 'zero erosion' ages for the pediment between ~600 and 300ka only partly overlap the shore platform age range, more realistic exposure ages calculated for an erosion rate of 1m/Ma are between ~945 and 475ka, fitting the age range of the correlated shore platform. 10Be concentrations of the high fluvial terrace are highly scattered evidencing vertical mixing of clasts probably due to slow lowering of the surface. Although it is not possible to determine an age for this landform, the scattering among its 10Be concentrations implies that this marker is several hundreds of thousands of years old and that the high fluvial terrace began to form at ~1200ka or after. Finally, 10Be concentrations of the high fluvial terrace, the pediment and the shore platform are of the same order of magnitude, which is consistent with the clear morphologic correlation between these three types of landforms. These data suggest that the marine and continental landforms studied formed synchronously, with some local differences, during a long period of relative tectonic stability between ~(1200?) 800 and 500ka and uplifted after 500ka. Our results confirm recent studies showing a post-400±100ka renewal of uplift along the Pacific coast after a Lower to Middle Pleistocene period of slow uplift. Moreover, the extension of the surfaces suggests that a broad region of ~40km has been uplifted ca. 150m during the Quaternary.",
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Geochronology of pediments and marine terraces in north-central Chile and their implications for Quaternary uplift in the Western Andes. / Rodríguez, María Pía; Carretier, Sébastien; Charrier, Reynaldo; Saillard, Marianne; Regard, Vincent; Hérail, Gérard; Hall, Sarah; Farber, Dan; Audin, Laurence.

En: Geomorphology, Vol. 180-181, 01.01.2013, p. 33-46.

Resultado de la investigación: Article

TY - JOUR

T1 - Geochronology of pediments and marine terraces in north-central Chile and their implications for Quaternary uplift in the Western Andes

AU - Rodríguez, María Pía

AU - Carretier, Sébastien

AU - Charrier, Reynaldo

AU - Saillard, Marianne

AU - Regard, Vincent

AU - Hérail, Gérard

AU - Hall, Sarah

AU - Farber, Dan

AU - Audin, Laurence

PY - 2013/1/1

Y1 - 2013/1/1

N2 - In north-central Chile, a wide shore platform is morphologically connected with a high fluvial terrace and a pediment. The eastward extension of Quaternary coastal uplift in the Southern Central Andes is poorly constrained since no age correlation between marine and continental landforms has been reported. We use 26Al and 10Be concentrations to constrain the geomorphic evolution of these marine and continental landforms near the Choapa valley (31.6° S). 10Be ages for the shore platform indicate that this surface was repeatedly reoccupied during sea-level highstands between ~800 and 500ka and uplifted after 500ka. While 'zero erosion' ages for the pediment between ~600 and 300ka only partly overlap the shore platform age range, more realistic exposure ages calculated for an erosion rate of 1m/Ma are between ~945 and 475ka, fitting the age range of the correlated shore platform. 10Be concentrations of the high fluvial terrace are highly scattered evidencing vertical mixing of clasts probably due to slow lowering of the surface. Although it is not possible to determine an age for this landform, the scattering among its 10Be concentrations implies that this marker is several hundreds of thousands of years old and that the high fluvial terrace began to form at ~1200ka or after. Finally, 10Be concentrations of the high fluvial terrace, the pediment and the shore platform are of the same order of magnitude, which is consistent with the clear morphologic correlation between these three types of landforms. These data suggest that the marine and continental landforms studied formed synchronously, with some local differences, during a long period of relative tectonic stability between ~(1200?) 800 and 500ka and uplifted after 500ka. Our results confirm recent studies showing a post-400±100ka renewal of uplift along the Pacific coast after a Lower to Middle Pleistocene period of slow uplift. Moreover, the extension of the surfaces suggests that a broad region of ~40km has been uplifted ca. 150m during the Quaternary.

AB - In north-central Chile, a wide shore platform is morphologically connected with a high fluvial terrace and a pediment. The eastward extension of Quaternary coastal uplift in the Southern Central Andes is poorly constrained since no age correlation between marine and continental landforms has been reported. We use 26Al and 10Be concentrations to constrain the geomorphic evolution of these marine and continental landforms near the Choapa valley (31.6° S). 10Be ages for the shore platform indicate that this surface was repeatedly reoccupied during sea-level highstands between ~800 and 500ka and uplifted after 500ka. While 'zero erosion' ages for the pediment between ~600 and 300ka only partly overlap the shore platform age range, more realistic exposure ages calculated for an erosion rate of 1m/Ma are between ~945 and 475ka, fitting the age range of the correlated shore platform. 10Be concentrations of the high fluvial terrace are highly scattered evidencing vertical mixing of clasts probably due to slow lowering of the surface. Although it is not possible to determine an age for this landform, the scattering among its 10Be concentrations implies that this marker is several hundreds of thousands of years old and that the high fluvial terrace began to form at ~1200ka or after. Finally, 10Be concentrations of the high fluvial terrace, the pediment and the shore platform are of the same order of magnitude, which is consistent with the clear morphologic correlation between these three types of landforms. These data suggest that the marine and continental landforms studied formed synchronously, with some local differences, during a long period of relative tectonic stability between ~(1200?) 800 and 500ka and uplifted after 500ka. Our results confirm recent studies showing a post-400±100ka renewal of uplift along the Pacific coast after a Lower to Middle Pleistocene period of slow uplift. Moreover, the extension of the surfaces suggests that a broad region of ~40km has been uplifted ca. 150m during the Quaternary.

KW - Chile

KW - CRN dating

KW - Fluvial terraces

KW - Pediment

KW - Shore platform

KW - Uplift

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U2 - 10.1016/j.geomorph.2012.09.003

DO - 10.1016/j.geomorph.2012.09.003

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JO - Geomorphology

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