El Intrusivo Florentina, del Complejo Volcánico Piroclástico del Río Chubut Medio Paleoceno – Eoceno medio): un ejemplo de etmolito o embudo

E. ARAGÓN, Y. E. AGUILERA, P. GONZÁLEZ, L. GÓMEZ PERAL, C. CAVAROZZI

Revista de la Asociación Geológica Argentina

Asociación Geológica Argentina

Lugar: Buenos Aires; Año: 2001 vol. 56 p. 161 - 172

0004-4822

The Florentina Intrusive from Middle Rio Chubut Volcanic-Piroclastic Complex: an example of Etmolith or Funnel. The Florentina Intrusive is a subvolcanic igneous body that belongs to Middle Rio Chubut Volcanic-Piroclastic Complex. The country rocks of the intrusion are the Tufolitas Laguna del Hunco. The body has not been developed a contact metamorphic aureola and it has a funnel-like intrusion or etmolith with 2 km in diameter. The rocks are mostly andesites-trachyandesites with three types of plagioclase fenocristals, two generations of clinopyroxene and one of olivine. The rocks has a strongly flow banding that lies concordant respect with the limit of the body. The andesites-trachyandesites are calcalkaline, meta-aluminous and sodic-potasic signature. The funnel intrusion shows a moderately internal compositional zonation of the rocks, with more silicic borders than the core. This zonation is the results of at least two simultaneous magma inyections that it were inyected trough a subvertical tabular dyke. This dyke joint the funnel-like intrusion with a subjacent magmatic chamber. The magmatic reservoir probably has been zoned too, with a more silicic roof than the floor. This zoning suggest a ballooning type emplacement of the etmolith magma pulses.