Petrologic characterization and tectonic implications of blueschist and greenschist facies rocks of Jambaló, Cauca
Jambaló greenschist and blueschist are found in a metamorphic unit that belongs to the Arquía complex. Metamorphism of these rocks is associated with the subduction of the Proto-Caribbean under the South American plate. Age of metamorphism has been estimated by Bustamante (2008) with Ar-Ar method as...
- Autores:
-
Carmona Mongua, Valentina
- Tipo de recurso:
- Trabajo de grado de pregrado
- Fecha de publicación:
- 2017
- Institución:
- Universidad de los Andes
- Repositorio:
- Séneca: repositorio Uniandes
- Idioma:
- eng
- OAI Identifier:
- oai:repositorio.uniandes.edu.co:1992/39911
- Acceso en línea:
- http://hdl.handle.net/1992/39911
- Palabra clave:
- Geología estructural
Petrología
Esquistos
Geociencias
- Rights
- openAccess
- License
- http://creativecommons.org/licenses/by-nc-sa/4.0/
| Summary: | Jambaló greenschist and blueschist are found in a metamorphic unit that belongs to the Arquía complex. Metamorphism of these rocks is associated with the subduction of the Proto-Caribbean under the South American plate. Age of metamorphism has been estimated by Bustamante (2008) with Ar-Ar method as Maastrichtian-Danian (67-61 Ma). Paragenesis of blueschist facies rocks is Glaucophane (Fe-glaucophane) + quartz + phengite + albite + epidote + chlorite (pycnochlorite) garnet, and paragenesis of greenschist facies rock is albite + quartz + chlorite (pycnochlorite) + calcite + epidote. Greenschist rocks have been altered by an infiltrating fluid with CO2, transforming the paragenesis from a paragenesis with actinolite to a paragenesis with calcite and with absence of actinolite. Protholits of theses rocks were obtained through mineral chemistry, whole rock composition and paragenesis analysis, defining a metapelitic protholit for blueschist rocks and a metabasic protholit for greenschist rocks. According to P-T conditions, both rock types reached approximately the metamorphic peak at 9.2 kbar and 481°C, which corresponds to the transitional assemblage between greenschist to blueschist facies. Petrography provides evidence of retrogression with a slight overprint of a lower facies (greenschist). However, rocks preserve their peak assemblage, indicating a hairpin retrograde path. According to this path and to lithologic relations between the studied rocks, it was suggested an exhumation of serpentinite-subduction channel type |
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