HR: 0800h
AN: V41B-0599    [Abstracts]
TI: Volcanic Degassing of Halogens and Trace Metals at Mt Etna, Sicily – A Melt Inclusion Investigation
AU: * Collins, S J
EM: sjc233@cam.ac.uk
AF: The University of Cambridge, Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ, United Kingdom
AU: Pyle, D M
EM: david.pyle@earth.ox.ac.uk
AF: The University fo Oxford, Department of Earth Sciences, University of Oxford, Parks Road, Oxford, OX1 3PR, United Kingdom
AU: Maclennan, J
EM: jmac05@esc.cam.ac.uk
AF: The University of Cambridge, Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ, United Kingdom
AU: Mather, T A
EM: tamsin.mather@earth.ox.ac.uk
AF: The University fo Oxford, Department of Earth Sciences, University of Oxford, Parks Road, Oxford, OX1 3PR, United Kingdom
AB: The process of volcanic degassing has important implications for eruption style, environmental impact of volcanic aerosols and economic mineralization processes at depth. Mt Etna, Sicily is persistently degassing, and responsible for 5-10% of global annual volcanic emissions of CO₂, SO₂ and volatile trace metals. We collected a suite of olivine hosted melt inclusions and matrix glasses in newly erupted products from Mt Etna, Sicily, spanning the major eruptions of the previous 6 years. These glasses have been measured for the concentrations of volatile (H, C, Cl, F) and trace elements (Li, Zr) by ion microprobe at the University of Edinburgh and for major and trace elements with a particular focus on the volatile trace metals by electron microprobe and laser ablation ICP-MS at the University of Cambridge. Volatile and trace element concentrations in melt inclusions allow us to constrain the storage, gas accumulation and degassing processes at Mt Etna over the past 6 years. The 2004-2007 melts were residual from the 2001- 2003 and were stored at a shallow depth where they evolved and equilibrated with a CO₂-rich, H₂O- poor flux of gas from depth. Because the life cycle of these melts is now well understood we can use new data of halogen and trace metal compositions from these same melt inclusions to determine the effect the shallow degassing process has on the behaviour of such environmentally and economically important elements. Trace metals and the halide forming elements are enriched in the volcanic plume of Etna partly because of their volatile behaviour and also due to the formation of stable complexes with the hard ligands Cl, F and S. Removal of metals from the melt by the process of shallow degassing will deplete the residual melt in trace metals and remove these elements from the volcanic system preventing ore formation, while enhancing the concentrations in the volcanic plume. We investigate the extent at which this has occurred on Mt Etna over the past 6 years.
DE: 1043 Fluid and melt inclusion geochemistry
DE: 1065 Major and trace element geochemistry
DE: 8424 Hydrothermal systems (0450, 1034, 3017, 3616, 4832, 8135)
DE: 8425 Effusive volcanism
DE: 8430 Volcanic gases
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting