Partitioning and equilibration of Rb and Sr between silicate melts and aqueous fluids

Abstract

Trace element concentrations in aqueous fluids in equilibrium with haplogranitic melt were determined in situ at elevated P-T conditions using hydrothermal diamond-anvil cells and synchrotron-radiation XRF microanalyses. Time-resolved analyses showed that the Rb and Sr concentrations in the fluids became constant in less than 2000 s at all temperatures (500 to 780°C). Although fluid-melt equilibration was very rapid, the change in the concentration of both elements in the fluid with temperature was fairly small (a slight increase for Rb and a slight decrease for Sr). This permitted partitioning data for Rb and Sr between haplogranitic melt and H 2 O or NaCl + KCl + HCl aqueous solutions at 750°C and 200 to 700 MPa to be obtained from EMP analyses of the quenched melt and the in situ SR-XRF analyses of the equilibrated fluid.

Large-ion lithophile elements delivered by saline fluids to the sub-arc mantle

“…D fluid=melt Sr in the haplogranite-water is larger than that in the jadeitewater system at similar pressure ( Figure 4C). The D fluid=melt Sr data in the haplogranite-water system of the present study are larger than those by Borchert et al (2009Borchert et al ( , 2010a at similar pressures.…”

“…The other data are consistent with one another and plotted on a positive trend with pressure ( Figure 4A). D fluid=melt Rb data reported by Borchert et al (2009Borchert et al ( , 2010a) are plotted at a lower D fluid/melt for each pressure than those of the present study, except for a datum at D = 0.22 and 0.7 GPa ( Figure 4B). D fluid=melt Sr in the haplogranite-water is larger than that in the jadeitewater system at similar pressure ( Figure 4C).…”

“…For the latter, the recess in the diamond anvil is filled with aqueous fluid, and XRF spectra of the fluid are obtained by using the 90°s cattering angle geometry between the incident X-ray and detector. Borchert et al (2009) determined concentrations of Rb and Sr in aqueous fluids coexisting with haplogranite melts under HTHP conditions, and they also analyzed quenched glasses to calculate the partition coefficients between them. Borchert et al (2010b) determined concentrations of Ba, La, Yb, and Y in aqueous fluids, employing similar methods but with higher excitation energy.…”

“…In situ analyses of aqueous fluids have been carried out using Bassett-type HDACs either with normal diamond anvils (Sanchez-Valle et al 2003;Bureau et al 2005;Muñoz et al 2005;Bureau et al 2007Bureau et al , 2010 or with modified anvils with a recess (Schmidt and Rickers 2003;Manning et al 2008;Borchert et al 2009Borchert et al , 2010a. For the former, by using transmission geometry ( Figure 1C), Sanchez-Valle et al (2003) obtained Sr concentrations in aqueous fluids coexisting with SrCO 3 crystals under HTHP conditions, and Bureau et al (2007) analyzed both melts and fluids under HTHP conditions and reported the first in situ partition coefficients of Pb between haplogranite melts and aqueous fluids with and without Cl.…”

Chemical composition of fluid inclusions in the Yorii jadeite–quartz rocks from the Kanto Mountains, Japan

“…This corresponds to the experimental result that the presence of NaCl suppresses the solubility of HFSE in aqueous fluids (Tsay et al, 2017). This feature is in contrast to more LILE dissolved in saline fluids than Clfree fluids (Keppler, 1996;Borchert et al, 2009Borchert et al, , 2010aBorchert et al, , 2010bKawamoto et al, 2014).…”