First analyses of tephra from the 2008 PASADO cores from Laguna Potrok Aike
2010 (English)In: Potrok Aike Maar Lake Sediment Archive Drilling Project, Berlin: GeoUnion Alfred-Wegener-Stiftung , 2010, 63-64 p.Conference paper (Other academic)
A total of 15 samples were analysed at the Tephrochronology Analytical Unit at the University of Edinburgh in November 2009, of which 14 are from the reference core and one is from the catchment area. Geochemical analyses were performed on a five-spectrometer Cameca SX-100 electron microprobe for concentrations of ten major oxides (Si, Al, Fe, Ti, Mn, Mg, Ca, Na, K & P). Most samples consisted of a mixture of pure glass (sometimes contaminated by phenocrysts) and minerals. Analyses of the glass show that all layers except T-35 are rhyolitic with SiO2 contents between ca 74.5 and 78% (Fig. 1). Two main groups occur, one group with K2O contents between ca 1.5 and 2.0%, indicating an origin in the Mt. Burney volcano and one group with K2O% contents between ca 2.5 and 3.2%, which suggests that these layers are products of eruptions of the Reclús volcano. The dacitic T-35 layer (SiO2 ca 70.5%) is geochemically similar to the t5-8 layer, described by Haberzettl et al. (2009) in a previous core from Laguna Potrok Aike, with an estimated age of ca 34 ka. Efforts will be undertaken in order to compare the geochemical data with previous tephrochronological studies on Laguna Potrok Aike and other sites in southernmost Patagonia. Three tephra samples have been submitted for Ar-Ar dating which will improve the chronological control of the lower part of the sediment record.
Place, publisher, year, edition, pages
Berlin: GeoUnion Alfred-Wegener-Stiftung , 2010. 63-64 p.
, Terra Nostra, ISSN 0946-8978 ; 2010/1
Research subject Quarternary Geology
IdentifiersURN: urn:nbn:se:su:diva-42099OAI: oai:DiVA.org:su-42099DiVA: diva2:343939
2nd International ICDP Workshop PASADO