2018 University of Maryland Geology Dept. Colloquium Series
Friday, September 28th 2018 at 3:00 pm
in PLS 1130, UMD College Park
Carnegie Geophysical Laboratory
Permeability development in ascending magmas: implications for explosive vs. effusive eruption styles
Transitions in volcanic eruptive style in mafic magmas are poorly understood. While silicic systems are the most researched and publicized due to their explosive character, mafic volcanoes remain the dominant form of volcanism on the earth. Eruptions are typically effusive, but changes in flow behavior can result in explosive, ash generating episodes. The efficiency of volatiles to degas from an ascending magma greatly influences eruption style. It is well known that volatile exsolution in magmas is a primary driving force for volcanic eruptions, however the roles vesicles and syn-eruptive crystallization play in eruption dynamics are poorly understood. Because the merging of bubbles in magma is mitigated by melt viscosity, it is predicted that permeability development in mafic magma will occur at lower bubble volumes than in silicic magma. However, no study has been performed on experimental samples to provide evidence for this hypothesis. Furthe! rmore, it is unknown how microlites affect the degassing process in terms of facilitating or hindering permeability development. In this talk I will describe how experimental petrology can be employed to: 1) experimentally observe how melt viscosity alone affects permeability development in magmas and 2) understand the effects of syn-eruptive crystallization in vesiculating mafic magmas. Then I will apply our experimental findings to the 2008 eruption of Kasatochi volcano, AK.