INECOA   26036
INSTITUTO DE ECORREGIONES ANDINAS
Unidad Ejecutora - UE
artículos
Título:
NEOGENE MONOGENETIC VOLCANISM FROM THE NORTHERN PUNA: PRODUCTS AND ERUPTIVE STYLES.
Autor/es:
MARO, GUADALUPE; CAFFE, PABLO J.
Revista:
GEOLOGICAL SOCIETY OF LONDON SPECIAL PUBLICATION
Editorial:
Geological Society
Referencias:
Lugar: Londres; Año: 2017 vol. 446 p. 337 - 359
ISSN:
0305-8719
Resumen:
The Neogene mafic volcanism of the northern Puna, in the Central Andes, isrepresented by scoria cones and lava flows disperse in a wide region (~ 9150 km2)as isolated or poorly clustered centers. Although all products are basalticandesites to andesites, the behavior of these magmatic systems resemble thatseen in basaltic monogenetic fields. These centers were studied with the aim of defining the main volcanic lithofacies andevaluating the eruptive styles involved. The results suggest that eruptionsdeveloped under a dry Strombolian dynamic, with brief periods of lavafountaining and hydrovolcanism, the latter usually restricted to early stagesof cone construction. Changes in eruptive styles are thought to be caused byvariations of internal (e.g. magma ascent) and external conditions (e.g.surficial water availability). Transitions do not reflect compositionalchanges, as evidenced by the small chemical difference observed among productsof all studied eruptive centers.Stratigraphic analysis, in addition with few pre-existing radiometric dates, suggests thatthis volcanic activity occurred during Upper Miocene to Lower Pliocene times.This information supports the inference that these eruptions occurred beforethe peak of southern Puna mafic volcanism, as well as that they were coevalwith eruptions of some of the most important silicic calderas of theAltiplano-Puna Volcanic Complex. Furthermore, the good preservation of volcanicedifices reveals that erosion rates were extremely low, in agreement with higharidity conditions that prevailed in the Puna region since Mid- to UpperMiocene.