Tuesday, 28 August 2007 - 1:50 PM
2.P1.D-2
"Multiple shallow level sill intrusions coupled with hydromagmatic explosive eruptions mark the initial phase of Ferrar Magmatism in North Victoria Land, Antarctica"
Lothar Viereck-Goette, Institut fuer Geowissenschaften, Friedrich-Schiller-Universitaet Jena, Burgweg 11, 07747 Jena, Germany, Robert Schöner, Institut für Geowissenschaften, Friedrich-Schiller-Universität Jena, Burgweg 11, Jena, 07749, Germany, Benjamin Bomfleur, Geologisch-Paläontologisches Institut, Westfälische Wilhelms-Universität Münster, Hindenburgplatz 57, Münster, 48143, Germany, and Jörg Schneider, Institut für Geologie, TU Bergakademie Freiberg, Bernhard-von-Cotta Str. 2, Freiberg, 09596, Germany.
Abstract Field data gathered during GANOVEX IX (2005/2006) in North Victoria Land, Antarctica, indicate that volcaniclastics of phreatomagmatic eruptions (so-called Exposure Hill Type events) are intercalated into fluvial deposits of Triassic-Jurassic age at two stratigraphic levels. Abundant scoriaceous spatter (locally welded) indicates a hawaiian/strombolian component. Breccia filled diatremes, from which the volcaniclastics were erupted, are rooted in sills which intrude wet sediments. The sediments are thus subaerial expressions of initial Ferrar magmatism as multiple shallow level sills. Due to magma-sediment interaction abundant clastic dikes are developed that intrude the sediments and sills. All igneous components in the volcaniclastic sediments are andesitic in composition as are the chilled margins of the sills. They are more differentiated than the basaltic andesites of the younger effusive section of Kirkpatrick plateau lavas which start with pillow lavas and small volume lava flows from volcanic necks.