Metamorfismo de muy bajo grado asociado a un sistema geotermal en rocas volcánicas básicas del Jurásico Medio, Formación Lonco Trapial, Paso Berwin, Chubut extra-andino

Translated title of the contribution: 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

P. Montecinos, C. Fuentealba, L. Aguirre, F. Hervé, E. Fonseca, M. J. Haller

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

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-SO2-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.

Translated title of the contributionVery low grade metamorphism associated with a geothermal system in basic volcanic rocks of the Middle Jurassic, Lonco Trapial Formation, Paso Berwin, Extra-Andean Chubut
Original languageSpanish
Pages (from-to)607-618
Number of pages12
JournalRevista de la Asociacion Geologica Argentina
Volume59
Issue number4
Publication statusPublished - Dec 2004

ASJC Scopus subject areas

  • Geology
  • Stratigraphy

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