SciELO - Scientific Electronic Library Online

 
vol.59 número4Procedencia de areniscas del Grupo Chubut en el área central de la Sierra de San Bernardo. Análisis preliminarLas Andesitas Estrechura del Complejo Volcánico Piroclástico del Río Chubut Medio (Paleoceno-Eoceno Medio) índice de autoresíndice de materiabúsqueda de artículos
Home Pagelista alfabética de revistas  

Servicios Personalizados

Revista

Articulo

Indicadores

  • No hay articulos citadosCitado por SciELO

Links relacionados

  • No hay articulos similaresSimilares en SciELO

Compartir


Revista de la Asociación Geológica Argentina

versión impresa ISSN 0004-4822

Resumen

MONTECINOS, P. et al. Very low grade metamorphism associated with a geothermal system in basic volcanic rocks of the Middle Jurassic, Lonco Trapial Formation, Paso Berwin, Extra-Andean Chubut. Rev. Asoc. Geol. Argent. [online]. 2004, vol.59, n.4, pp.607-618. ISSN 0004-4822.

The basic volcanic rocks of the Lonco Trapial Formation, have a primary mineralogy mainly composed of olivine, calcic plagioclase and pyroxene, and present a large quantity of amygdales. Their metamorphic mineralogy is characterized by zeolites, clay and micaceous minerals. The main mineral association includes celadonite, montmorillonite, heulandite, analcime, gonnardite and subordinate levyne and minerals of the wairakite-analcime series. This association belongs to the zeolite facies and its origin was associated with a geothermal system. The analogy with known zeolite zones in equivalent geothermal systems and the use of the petrogenetic grid for zeolite parageneses, in the system An-Ab-SiO2-H2O, permits to establish a range of temperature between 80°-180°C. A single metamorphic hidrothermal event would have taken place in presence of a CO2 very poor fluid phase, whose chemical composition possibly changed from a neutral character with low a(SiO2) and moderate a(K2O) (allowing precipitation of smectites and celadonite) to a neutral-alkaline character with high a(SiO2) that allows heulandite to be stable.

Palabras clave : Chubut extrandino; Geothermal system; Zeolite facies; Hidrotermal metamorphism; Very low grade metamorphism.

        · resumen en Español     · texto en Español     · Español ( pdf )

 

Creative Commons License Todo el contenido de esta revista, excepto dónde está identificado, está bajo una Licencia Creative Commons