PALEOENVIRONMENTAL RECONSTRUCTIONS OF THE PLEISTOCENE ICE SHEET INFORMED BY GLACIO-VOLCANIC DEPOSITS IN NORTHEAST ICELAND

The recent instability of weather, sea level change, and melting of glaciers have resulted in hazards due to climate change. In particular, there are indications that glacial retreat can lead to increased eruption rates by destabilizing existing magma bodies and even prompting new magma generation (Pagli and Sigmundsson, 2008). The ideal locality on Earth to study volcano-ice interactions is Iceland, an active volcanic island that has been totally covered in previous ice ages which have led to unique glacio-volcanic landforms. Broadly, glacio-volcanism is the study of volcano-ice interactions. Glacio-volcanic deposits hold information concerning the existing environmental conditions at the time of eruption and can reflect ice thickness changes over time in the Pleistocene. One of the main products of volcano-ice interactions is volcanic glass, whether as glassy rims on pillow basalts or glassy fragments in hyaloclastites. Volcanic glass forms by rapid cooling when hot magma quenches against ice and its meltwater. Volcanic glasses contain dissolved volatiles such as water, carbon dioxide, sulfur, and chlorine. The pressure-dependence of volatile solubility in magmas allows estimation of the ice thickness at the time of eruption by measuring the volatile content of glacio-volcanic glasses. We present the first glass-based study of three glacio-volcanic edifices (Gæsafjöll, Bláfjall, and Burfell) in northeast Iceland to understand the paleoenvironmental conditions of eruption during the Pleistocene. The hypothesis to be tested is that the Pleistocene ice sheet thickened toward the south where Vatnajökull glacier remains today. Major elements of the glass and sulfur and chlorine will be analyzed by electron microprobe (EM) at the University of Wisconsin-Madison. Water and carbon dioxide will be analyzed by Fourier Transform Infrared (FTIR) spectrometry at the University of Wisconsin-Milwaukee.