Tephra glass geochemistry to synchronise sedimentary records and understand regional eruptive histories: a postglacial tephrochronological model for the Chilean Lake DistrictTipo de material: TextoIdioma: Inglés Detalles de publicación: 2016Descripción: digital (S2.9)Tema(s): Solicitar como:
|Tipo de ítem||Biblioteca actual||Colección||Solicitar como||Estado||Fecha de vencimiento||Código de barras|
|Artículos de Congresos||SERVICIO NACIONAL DE GEOLOGÍA Y MINERÍA (SERNAGEOMIN)||Colección Materiales Especiales||15272-a (Navegar estantería(Abre debajo))||Disponible|
Volcanic Hazard and Risk Assessment S2.9
Well-characterised tephra horizons deposited in various sedimentary environments provide a means of synchronising sedimentary archives and obtaining accurate chronological controls of past explosive eruptions. The use of tephra as a chronological tool is however still widely underutilised in southern Chile and Argentina. In this study we develop a postglacial tephrochronological model for the Chilean Lake District (ca. 38 to 42 °S) by integrating terrestrial and lacustrine records. Tephra deposits preserved in lake sediments record discrete events even if they do not correspond to primary fallout, and provide the most complete temporal records of recurrent ash fall impact in a given region. By combining terrestrial with lacustrine records we obtain the most complete tephrostratigraphic record for the area to date. Our open access glass geochemical and chronological dataset provides insights into the frequency and magnitude of large explosive eruptions impacting the Chilean Lake District throughout the postglacial. Most volcanoes in the studied segment of the Southern Volcanic Zone, between Llaima and Calbuco, have produced at least one regional marker deposit resulting from a large explosive eruption (magnitude ? 4), some of which now have a significantly improved age estimate. Others, including several units from Puyehue-Cordón Caulle, are newly described. We also find tephra related to the Cha1 eruption from Chaitén volcano in lake sediments up to 400 km north from source. Several clear marker horizons are now identified that will help refine age model reconstructions for various sedimentary archives. Our chronological model suggests three distinct phases of eruptive activity impacting the area, with an early-to-mid-Holocene period of relative quiescence. Extending our tephrochronogical framework further south into Patagonia will allow a more detailed evaluation of the controls on the occurrence and magnitude of explosive eruptions throughout the postglacial.