Late Paleozoic K/Ar ages of blueschists from Pichilemu, Central Chile

Francisco Herve, Francisco Munizaga, Estanislao Godoy, Luis Aguirre

Resultado de la investigación: Article

22 Citas (Scopus)

Resumen

Two crossite concentrates and one blueschist whole rock were analyzed by the K/Ar method. These samples belong to the high/intermediate pressure Western Series of the Chilean metamorphic basement and, in this area, are intruded by a small monzonite body. Ages obtained were 211 m.y. and 329 m.y. for the mineral concentrates and 211 m.y. for the whole rock. Discussion based on crystal size as a factor for retention of 40Ar during localized re-heating of the metamorphic rocks due to the monzonitic intrusion leads to the acceptance of 329 m.y. as the minimum age of crossite crystallization. This age agrees with the whole rock Rb/Sr limiting reference isochrons (273-342 m.y.) previously obtained for the metamorphic basement of Central Chile which did not include samples of the present area. This age provides the first evidence of a Paleozoic blueschist assemblage in the eastern Pacific border and would suggest the existence of a Late Paleozoic subduction zone along the western margin of South America.

Idioma originalEnglish
Páginas (desde-hasta)261-264
Número de páginas4
PublicaciónEarth and Planetary Science Letters
Volumen23
N.º2
DOI
EstadoPublished - 1974

Huella dactilar

blueschist
Chile
Paleozoic
crossite
Rocks
rocks
basements
Metamorphic rocks
metamorphic rocks
rock
Crystallization
borders
intrusion
acceptability
Minerals
monzonite
margins
minerals
crystallization
metamorphic rock

ASJC Scopus subject areas

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

Citar esto

Herve, Francisco ; Munizaga, Francisco ; Godoy, Estanislao ; Aguirre, Luis. / Late Paleozoic K/Ar ages of blueschists from Pichilemu, Central Chile. En: Earth and Planetary Science Letters. 1974 ; Vol. 23, N.º 2. pp. 261-264.
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Late Paleozoic K/Ar ages of blueschists from Pichilemu, Central Chile. / Herve, Francisco; Munizaga, Francisco; Godoy, Estanislao; Aguirre, Luis.

En: Earth and Planetary Science Letters, Vol. 23, N.º 2, 1974, p. 261-264.

Resultado de la investigación: Article

TY - JOUR

T1 - Late Paleozoic K/Ar ages of blueschists from Pichilemu, Central Chile

AU - Herve, Francisco

AU - Munizaga, Francisco

AU - Godoy, Estanislao

AU - Aguirre, Luis

PY - 1974

Y1 - 1974

N2 - Two crossite concentrates and one blueschist whole rock were analyzed by the K/Ar method. These samples belong to the high/intermediate pressure Western Series of the Chilean metamorphic basement and, in this area, are intruded by a small monzonite body. Ages obtained were 211 m.y. and 329 m.y. for the mineral concentrates and 211 m.y. for the whole rock. Discussion based on crystal size as a factor for retention of 40Ar during localized re-heating of the metamorphic rocks due to the monzonitic intrusion leads to the acceptance of 329 m.y. as the minimum age of crossite crystallization. This age agrees with the whole rock Rb/Sr limiting reference isochrons (273-342 m.y.) previously obtained for the metamorphic basement of Central Chile which did not include samples of the present area. This age provides the first evidence of a Paleozoic blueschist assemblage in the eastern Pacific border and would suggest the existence of a Late Paleozoic subduction zone along the western margin of South America.

AB - Two crossite concentrates and one blueschist whole rock were analyzed by the K/Ar method. These samples belong to the high/intermediate pressure Western Series of the Chilean metamorphic basement and, in this area, are intruded by a small monzonite body. Ages obtained were 211 m.y. and 329 m.y. for the mineral concentrates and 211 m.y. for the whole rock. Discussion based on crystal size as a factor for retention of 40Ar during localized re-heating of the metamorphic rocks due to the monzonitic intrusion leads to the acceptance of 329 m.y. as the minimum age of crossite crystallization. This age agrees with the whole rock Rb/Sr limiting reference isochrons (273-342 m.y.) previously obtained for the metamorphic basement of Central Chile which did not include samples of the present area. This age provides the first evidence of a Paleozoic blueschist assemblage in the eastern Pacific border and would suggest the existence of a Late Paleozoic subduction zone along the western margin of South America.

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