%0 Journal Article
%T Geochemical signatures of tephras from Quaternary Antarctic Peninsula volcanoes Geoqu¨ªmica de tefras de volcanes Cuaternarios de la Pen¨ªnsula Ant¨¢rtica
%A Stefan Kraus
%A Andrei Kurbatov
%A Martin Yates
%J Andean Geology
%D 2013
%I Servicio Nacional de Geolog¨ªa y Miner¨ªa (SERNAGEOMIN)
%X In the northern Antarctic Peninsula area, at least 12 Late Plelstocene-Holocene volcanic centers could be potential sources of tephra layers in the region. We present unique geochemical fingerprints for ten of these volcanoes using major, trace, rare earth element, and isotope data from 95 samples of tephra and other eruption products. The volcanoes have predominantly basaltic and basaltic andesitic compositions. The Nb/Y ratio proves useful to distinguish between volcanic centers located on the eastern (Larsen Rift) and those situated on the western side (Bransfield Rift) of the Antarctic Peninsula. In addition, the Sr/Nb ratio (for samples with SiO2 <63 wt%), along with Sr/Y, Ba/La, Zr/Hf and Th/Nb are suitable to unequivocally characterize material erupted from every studied volcanic center. Microprobe analyses on volcanic glass show that the samples are generally very poor in K2O, and that glass from Bransfield Rift volcanoes is enriched in SiO2, while that of Larsen Rift volcanoes tends towards elevated alkali contents. We propose an algorithm for the identification of the source volcano of a given tephra layer using the new geochemical fingerprints. This will contribute to the development of a regional tephrochronological framework needed for future correlations of tephra in climate archives (e.g., marine, lacustrine and ice cores). En la parte norte de la Pen¨ªnsula Ant¨¢rtica existen, por lo menos, 12 centros volc¨¢nicos del Pleistoceno Tard¨ªo-Holoceno que podr¨ªan representar las fuentes de horizontes de tefra reconocidos en la regi¨®n. Se reportan aqu¨ª an¨¢lisis qu¨ªmicos de 10 de estos volcanes, que incluyen an¨¢lisis de elementos mayores, trazas, tierras raras y composici¨®n isot¨®pica de 95 muestras de tefra u otros productos eruptivos. Los volcanes tienen, en su mayor¨ªa, composici¨®n bas¨¢ltica a bas¨¢ltico-andes¨ªtica. Las razones Nb/Y resultan ¨²tiles para distinguir entre centros volc¨¢nicos ubicados al lado oriental (Larsen Rift) de aquellos ubicados al lado occidental (Bransfield Rift) de la Pen¨ªnsula Ant¨¢rtica. Adicionalmente, las razones Sr/Nb (para muestras con SiO2 <63 wt%), Sr/Y, Ba/La, Zr/Hf y Th/Nb sirven para caracterizar los productos generados por cada centro volc¨¢nico. An¨¢lisis de microsonda en vidrio muestran que las rocas estudiadas tienen bajos contenidos de K2O, y que vidrios de rocas provenientes de volcanes ubicados en el rift de Bransfield son ricos en SiO2, mientras que las de volcanes del rift de Larsen tienden hac¨ªa contenidos elevados de ¨¢lcalis. Se propone un algoritmo para la identificaci¨®n del volc¨¢n de origen de un horizonte
%K Pleistoceno Tard¨ªo
%K Holoceno
%K Volcanismo explosivo
%K Tefra
%K Volc¨¢n de origen
%K Huella geoqu¨ªmica
%K Pen¨ªnsula Ant¨¢rtica
%K Rift de Bransfield
%K Rift de Larsen
%K Late Pleistocene
%K Holocene
%K Explosive volcanism
%K Tephra
%K Source volcano identification
%K Geochemical fingerprint
%K Antarctic Peninsula
%K Bransfield Rift
%K Larsen Rift
%U http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-71062013000100001