Crustal thickness beneath the Andes and Sierras Pampeanas at 30°S inferred from Pn apparent phase velocities

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Abstract

We obtained a 2D crustal model beneath central Chile and western Argentina using apparent Pn phase velocities recorded along an EW trending transect at 30°S. This model is characterized by a thick (65 km) crustal root beneath the High Cordillera, a 60 km thick crust beneath the Precordillera, and a gradual shallowing of Moho depths beneath the Sierras Pampeanas from 55 km in the west to 40 km in the east. Beneath the Sierras Pampeanas, where very little crustal shortening is observed, the thick crust must be explained by means other than simple tectonic shortening. Isostatically balanced crustal thickness is consistently shallower than our model shows, suggesting the existence of dynamic forces possibly linked to the flat slab.

Original languageEnglish (US)
JournalGeophysical Research Letters
Volume31
Issue number6
StatePublished - Mar 28 2004

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phase velocity
crustal thickness
crusts
crustal root
crust
Argentina
crustal shortening
Chile
Moho
cordillera
tectonics
slab
slabs
transect

ASJC Scopus subject areas

  • Earth and Planetary Sciences (miscellaneous)

Cite this

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title = "Crustal thickness beneath the Andes and Sierras Pampeanas at 30°S inferred from Pn apparent phase velocities",
abstract = "We obtained a 2D crustal model beneath central Chile and western Argentina using apparent Pn phase velocities recorded along an EW trending transect at 30°S. This model is characterized by a thick (65 km) crustal root beneath the High Cordillera, a 60 km thick crust beneath the Precordillera, and a gradual shallowing of Moho depths beneath the Sierras Pampeanas from 55 km in the west to 40 km in the east. Beneath the Sierras Pampeanas, where very little crustal shortening is observed, the thick crust must be explained by means other than simple tectonic shortening. Isostatically balanced crustal thickness is consistently shallower than our model shows, suggesting the existence of dynamic forces possibly linked to the flat slab.",
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T1 - Crustal thickness beneath the Andes and Sierras Pampeanas at 30°S inferred from Pn apparent phase velocities

AU - Fromm, R.

AU - Zandt, George

AU - Beck, Susan

PY - 2004/3/28

Y1 - 2004/3/28

N2 - We obtained a 2D crustal model beneath central Chile and western Argentina using apparent Pn phase velocities recorded along an EW trending transect at 30°S. This model is characterized by a thick (65 km) crustal root beneath the High Cordillera, a 60 km thick crust beneath the Precordillera, and a gradual shallowing of Moho depths beneath the Sierras Pampeanas from 55 km in the west to 40 km in the east. Beneath the Sierras Pampeanas, where very little crustal shortening is observed, the thick crust must be explained by means other than simple tectonic shortening. Isostatically balanced crustal thickness is consistently shallower than our model shows, suggesting the existence of dynamic forces possibly linked to the flat slab.

AB - We obtained a 2D crustal model beneath central Chile and western Argentina using apparent Pn phase velocities recorded along an EW trending transect at 30°S. This model is characterized by a thick (65 km) crustal root beneath the High Cordillera, a 60 km thick crust beneath the Precordillera, and a gradual shallowing of Moho depths beneath the Sierras Pampeanas from 55 km in the west to 40 km in the east. Beneath the Sierras Pampeanas, where very little crustal shortening is observed, the thick crust must be explained by means other than simple tectonic shortening. Isostatically balanced crustal thickness is consistently shallower than our model shows, suggesting the existence of dynamic forces possibly linked to the flat slab.

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