Metamorfismo de facies prehnita-pumpellyita en la formación abanico del cenozoico, Andes centrales de Chile (33°50'S): Controles químicos y de escala sobre las asociaciones minerales, el progreso de la reacción y el estado de equilibrio

Marcia Muñoz, Luis Aguirre, Mario Vergara, Alain Demant, Francisco Fuentes, Andrés Fock

Resultado de la investigación: Article

6 Citas (Scopus)

Resumen

In the El Volcán and Rodeo de los Bueyes areas, Andean Principal Cordillera (east of Santiago; 33o50'S), an Upper Oligocene-Lower Miocene volcanic series belonging to the Abanico Formation (Late Eocene-Early Miocene) is exposed. The rock successions outcropping in both areas, ca. 3,300 m total thickness, have been affected by very low-grade, non-deformative metamorphism in the prehnite-pumpellyite facies. This is represented by the widespread development of secondary mineral assemblages composed of epidote, mixed-layer chlorite-smectite, albite, quartz, white mica, and titanite. These mineral assemblages also contain pumpellyite, prehnite or prehnite+actinolite in a few samples. Chemical characteristics, such as low compositional variability of mixed-layer chlorite-smectite and actinolite independent from the metadomain where these phases are hosted, along with a high proportion of chlorite layers in the former, suggest that these phases closely represent the whole rock effective bulk composition. On the contrary, pumpellyite compositions show a higher variability and a strong metadomain control evidencing its lower equilibration kinetics and leaving only those that grow in the rock matrix as the more closely representative of a whole rock effective bulk compositional control. Mineral assemblages from both areas show evidence of having been formed during the same metamorphic event where reactions have ocurred equivalently between them. However, local differences in chemical variables controlling this process are recognizable. A higher CO2 concentration in the fluids during the metamorphism in the El Volcán area than in the Rodeo de los Bueyes area is suggested by the scarce development of prehnite and the ubiquitous presence of calcite in the metamorphic assemblages of the former. Pressure and temperature of this metamorphic event have been roughly estimated to be lower than 2-3 kbar and 320oC, respectively.

Idioma originalSpanish
Páginas (desde-hasta)54-77
Número de páginas24
PublicaciónAndean Geology
Volumen37
N.º1
EstadoPublished - 2010

Huella dactilar

pumpellyite
prehnite
Minerals
metamorphism
Rocks
chlorite
mineral
rock
smectite
mixed layer
Miocene
Quartz
Calcium Carbonate
secondary mineral
titanite
epidote
albite
Chemical analysis
cordillera
mica

ASJC Scopus subject areas

  • Geology
  • Geochemistry and Petrology
  • Palaeontology
  • Stratigraphy

Citar esto

@article{6b761051aa5a42db8f51e12babbbf348,
title = "Metamorfismo de facies prehnita-pumpellyita en la formaci{\'o}n abanico del cenozoico, Andes centrales de Chile (33°50'S): Controles qu{\'i}micos y de escala sobre las asociaciones minerales, el progreso de la reacci{\'o}n y el estado de equilibrio",
abstract = "In the El Volc{\'a}n and Rodeo de los Bueyes areas, Andean Principal Cordillera (east of Santiago; 33o50'S), an Upper Oligocene-Lower Miocene volcanic series belonging to the Abanico Formation (Late Eocene-Early Miocene) is exposed. The rock successions outcropping in both areas, ca. 3,300 m total thickness, have been affected by very low-grade, non-deformative metamorphism in the prehnite-pumpellyite facies. This is represented by the widespread development of secondary mineral assemblages composed of epidote, mixed-layer chlorite-smectite, albite, quartz, white mica, and titanite. These mineral assemblages also contain pumpellyite, prehnite or prehnite+actinolite in a few samples. Chemical characteristics, such as low compositional variability of mixed-layer chlorite-smectite and actinolite independent from the metadomain where these phases are hosted, along with a high proportion of chlorite layers in the former, suggest that these phases closely represent the whole rock effective bulk composition. On the contrary, pumpellyite compositions show a higher variability and a strong metadomain control evidencing its lower equilibration kinetics and leaving only those that grow in the rock matrix as the more closely representative of a whole rock effective bulk compositional control. Mineral assemblages from both areas show evidence of having been formed during the same metamorphic event where reactions have ocurred equivalently between them. However, local differences in chemical variables controlling this process are recognizable. A higher CO2 concentration in the fluids during the metamorphism in the El Volc{\'a}n area than in the Rodeo de los Bueyes area is suggested by the scarce development of prehnite and the ubiquitous presence of calcite in the metamorphic assemblages of the former. Pressure and temperature of this metamorphic event have been roughly estimated to be lower than 2-3 kbar and 320oC, respectively.",
keywords = "Abanico Formation, Andes, Cenozoic, Prehnite-pumpellyite facies",
author = "Marcia Mu{\~n}oz and Luis Aguirre and Mario Vergara and Alain Demant and Francisco Fuentes and Andr{\'e}s Fock",
year = "2010",
language = "Spanish",
volume = "37",
pages = "54--77",
journal = "Andean Geology",
issn = "0718-7092",
publisher = "Servicio Nacional de Geologia y Mineria",
number = "1",

}

TY - JOUR

T1 - Metamorfismo de facies prehnita-pumpellyita en la formación abanico del cenozoico, Andes centrales de Chile (33°50'S)

T2 - Controles químicos y de escala sobre las asociaciones minerales, el progreso de la reacción y el estado de equilibrio

AU - Muñoz, Marcia

AU - Aguirre, Luis

AU - Vergara, Mario

AU - Demant, Alain

AU - Fuentes, Francisco

AU - Fock, Andrés

PY - 2010

Y1 - 2010

N2 - In the El Volcán and Rodeo de los Bueyes areas, Andean Principal Cordillera (east of Santiago; 33o50'S), an Upper Oligocene-Lower Miocene volcanic series belonging to the Abanico Formation (Late Eocene-Early Miocene) is exposed. The rock successions outcropping in both areas, ca. 3,300 m total thickness, have been affected by very low-grade, non-deformative metamorphism in the prehnite-pumpellyite facies. This is represented by the widespread development of secondary mineral assemblages composed of epidote, mixed-layer chlorite-smectite, albite, quartz, white mica, and titanite. These mineral assemblages also contain pumpellyite, prehnite or prehnite+actinolite in a few samples. Chemical characteristics, such as low compositional variability of mixed-layer chlorite-smectite and actinolite independent from the metadomain where these phases are hosted, along with a high proportion of chlorite layers in the former, suggest that these phases closely represent the whole rock effective bulk composition. On the contrary, pumpellyite compositions show a higher variability and a strong metadomain control evidencing its lower equilibration kinetics and leaving only those that grow in the rock matrix as the more closely representative of a whole rock effective bulk compositional control. Mineral assemblages from both areas show evidence of having been formed during the same metamorphic event where reactions have ocurred equivalently between them. However, local differences in chemical variables controlling this process are recognizable. A higher CO2 concentration in the fluids during the metamorphism in the El Volcán area than in the Rodeo de los Bueyes area is suggested by the scarce development of prehnite and the ubiquitous presence of calcite in the metamorphic assemblages of the former. Pressure and temperature of this metamorphic event have been roughly estimated to be lower than 2-3 kbar and 320oC, respectively.

AB - In the El Volcán and Rodeo de los Bueyes areas, Andean Principal Cordillera (east of Santiago; 33o50'S), an Upper Oligocene-Lower Miocene volcanic series belonging to the Abanico Formation (Late Eocene-Early Miocene) is exposed. The rock successions outcropping in both areas, ca. 3,300 m total thickness, have been affected by very low-grade, non-deformative metamorphism in the prehnite-pumpellyite facies. This is represented by the widespread development of secondary mineral assemblages composed of epidote, mixed-layer chlorite-smectite, albite, quartz, white mica, and titanite. These mineral assemblages also contain pumpellyite, prehnite or prehnite+actinolite in a few samples. Chemical characteristics, such as low compositional variability of mixed-layer chlorite-smectite and actinolite independent from the metadomain where these phases are hosted, along with a high proportion of chlorite layers in the former, suggest that these phases closely represent the whole rock effective bulk composition. On the contrary, pumpellyite compositions show a higher variability and a strong metadomain control evidencing its lower equilibration kinetics and leaving only those that grow in the rock matrix as the more closely representative of a whole rock effective bulk compositional control. Mineral assemblages from both areas show evidence of having been formed during the same metamorphic event where reactions have ocurred equivalently between them. However, local differences in chemical variables controlling this process are recognizable. A higher CO2 concentration in the fluids during the metamorphism in the El Volcán area than in the Rodeo de los Bueyes area is suggested by the scarce development of prehnite and the ubiquitous presence of calcite in the metamorphic assemblages of the former. Pressure and temperature of this metamorphic event have been roughly estimated to be lower than 2-3 kbar and 320oC, respectively.

KW - Abanico Formation

KW - Andes

KW - Cenozoic

KW - Prehnite-pumpellyite facies

UR - http://www.scopus.com/inward/record.url?scp=79955698109&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:79955698109

VL - 37

SP - 54

EP - 77

JO - Andean Geology

JF - Andean Geology

SN - 0718-7092

IS - 1

ER -