INVESTIGADORES
COIRA beatriz lidia luisa
artículos
Título:
Ordovician submarine to subaerial volcanism along the western Gondwana margin: records of Famatinian belt evolution, Eastern Pampean Sierras, Argentina
Autor/es:
CISTERNA, C.E.; COIRA B.L.
Revista:
INTERNATIONAL JOURNAL OF EARTH SCIENCES
Editorial:
SPRINGER
Referencias:
Lugar: Berlin; Año: 2020
ISSN:
1437-3254
Resumen:
The Suri-Las Planchadas Volcanic- Sedimentary Complex (SPVSC), northwester of the Eastern Pampean Sierras, Argentina, comprises an Early to Middle Arenigian submarine and subaerial successions with a variety of mafic to felsic volcanic lithofacies. These units include mafic to intermediate submarine massive- hyaloclastic lava flows, dacitic lavas, pyroclast rich volcaniclastic deposits, intrusions of domes/sills and rhyodacitic - rhyolitic lavas. Along Las Planchadas hill a section of ~3 km thick is exposed showing vertical and lateral variations. The lower part is dominated by massive, pillowed and basaltic to intermediate lavas, autobreccia and hyaloclastic facies, representing the beginning of the volcanic arc. The upper almost 2 km of the succession is dominated by subaqueous- resedimented volcaniclastic siltstones, sandstones and breccias with abundant pyroclastic components and rhydacitic to rhyolitic lava- domes, sills and dykes. Tuff and ignimbrite lithoclasts, abundant shards and pumice fragments were determined in the resedimented deposits. Volcanism in the SPVSC started with submarine eruptions and progressively grew probably above the wave base, accompanied by a change from basic to intermediate and felsic members. The eruptive pattern shifted from effusive to explosive, producing a large apron of syn- and post-eruptive volcaniclastic deposits of debris flows and turbidity currents. They are the proof of variations in composition and volcanic styles and their development contributed to generate an apron surrounding the volcanoes. The apron prograde with the evolution of the volcanism culminating in shallow water volcanogenic beds. The final compositionally most evolved phase was derived from felsic subaerial or shallow subaqueous explosive volcanism.
