title: An experimental study of the partitioning of trace elements between rutile and silicate melt as a function of oxygen fugacity.
abstract: Subduction zone or arc magmas are known to display a characteristic depletion of High Field Strength Elements (HFSE) relative to other similarly incompatible elements, which can be attributed to the presence of the accessory mineral rutile (TiO2) in the residual slab. Here we show that the partitioning behavior of vanadium between rutile and silicate melt varies from incompatible (∼0.1) to compatible (∼18) as a function of oxygen fugacity. We also confirm that the HFSE are compatible in rutile, with D(Ta)> D(Nb)>> (D(Hf)>/∼ D(Zr), but that the level of compatibility is strongly dependent on melt composition, with partition coefficients increasing about one order of magnitude with increasing melt polymerization (or decreasing basicity). Our partitioning results also indicate that residual rutile may fractionate U from Th due to the contrasting (over 2 orders of magnitude) partitioning between these two elements. We confirm that, in addition to the HFSE, Cr, Cu, Zn and W are compatible in rutile at all oxygen fugacity conditions.
authors.affiliation: Instituto de Geociências, Universidade de São Paulo, São Paulo, SP, Brasil.
authors.forename: Guilherme
authors.initials: G
authors.lastname: Mallmann
authors.affiliation: Steinmann Institut für Geologie, Mineralogie und Palëontologie, Universität Bonn, Bonn, Germany.
authors.forename: Raúl O C
authors.initials: RO
authors.lastname: Fonseca
authors.affiliation: Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, São Paulo SP, Brasil.
authors.forename: Adolfo B
authors.initials: AB
authors.lastname: Silva