Zajacz Zoltan, Candela Philip, Piccoli Philip, Sanchez-Valle Carmen, Walle Markus (2013), Solubility and partitioning behavior of Au, Cu, Ag and reduced S in magmas, in Geochimica et Cosmochimica Acta
, 112, 288-304.
Zajacz Zoltan, Candela Philip, Piccoli Philip, Sanchez-Valle Carmen (2012), The partitioning of sulfur and chlorine between andesite melts and magmatic volatiles and the exchange coefficients of major cations, in Geochimica et Cosmochimica Acta
, 89, 81-101.
The solubility of volatile elements (H, C, O, S, Cl) in silicate melts have been in the main focus of research in the past decades due to their important role in igneous petrogenesis, volcanic activity and ore deposit formation. Despite that large amount of existing experimental data, the speciation of oxidized S (S6+) and Cl in the silicate melt is still poorly known. Furthermore it is yet to be understood how various S, Cl and CO2 species interact in the silicate melt structure, as it may significantly affect their solubilities, and therefore the composition the volatile phase exsolving from the silicate melt. The research proposed here focuses on filling these gaps of knowledge. We will use an interdisciplinary approach to obtain information on the speciation of S and Cl in silicate melts. This will comprise experimental investigation of solubilities in systems with stepwise increasing complexity, spectroscopic studies (Raman, XANES, FTIR), ab initio quantum chemical calculation of the geometries and thermodynamic properties of plausible species, and classical molecular dynamics simulations of volatile solubilities. Furthermore, systematic sets of experiments will be conducted on a wide variety of natural melt compositions to explore the dependence of volatile/melt partition coefficients of S and Cl on pressure, temperature and melt composition. Our experiments will address conditions relevant for magma chambers and conduits underneath volcanoes (25-400 MPa, 750-1300 oC). All investigations are oriented towards facilitating the construction of an accurate thermodynamic model that predicts the equilibrium composition of multicomponent silicate melts and volatile phases.A doctoral student will focus on the investigation of the partitioning of volatile and metallic elements in silicate melt-vapor-brine systems at relatively low pressures (25-125 MPa) with the purpose of understanding syn- and preeruptive evolution of the volatile phase in magma reservoirs and volcanic conduits. Her/his research will also include a field component tracking the presence of residual brines or salt melts in freshly erupted volcanic rocks, which may also lead to development of new tools to understand eruption dynamics.