The partitioning of copper between silicate melts and two-phase aqueous fluids: An experimental investigation at 1 kbar, 800°?C and 0.5?kbar, 850°?C |
| |
| Authors: | T J Williams Philip A Candela Philip M Piccoli |
| |
| Institution: | (1) Laboratory for Mineral Deposits Research, Department of Geology, University of Maryland at College Park, College Park, MD 20742–4211, USA, US |
| |
| Abstract: | Experiments were performed in the three phase system high-silica rhyolite melt+low-salinity aqueous vapor+hydrosaline brine,
to investigate the partitioning equilibria for copper in magmatic-hydrothermal systems at 800° C and 1 kbar, and 850° C and
0.5 kbar. Daqm/mlt
Cu and apparent equilibrium constants, Kaqm/mlt
Cu,Na, between the aqueous mixture (aqm=quenched vapor+brine) and the silicate melt (mlt) are calculated. Daqm/mlt
Cu increases with increasing aqueous chloride concentration and is a function of pressure. Kaqm/mlt
Cu,Na=215(±73) at 1 kbar and 800° C and Kaqm/mlt
Cu,Na=11(±6) at 0.5 kbar and 850°C. Decreasing pressure from 1 to 0.5 kbar lowers Kaqm/mlt
Cu,Na by a factor of approximately 20. Data revealed no difference in Kaqm/mlt
Cu,Na or Daqm/mlt
Cu as a function of the melt aluminium saturation index. Within the 2-phase field the Kaqm/mlt
Cu,Na show no variation with total aqueous chloride, indicating that copper-sodium exchange between the vapor, brine and silicate
melt is independent of the mass proportion of vapor and brine. Model copper-sodium apparent equilibrium constants for the
hydrosaline brine and the silicate melt revealed a negative dependence on pressure. Model apparent equilibrium constants for
copper-sodium exchange between the brine and vapor were close to unity at 1 kbar and 800° C.
Received: 27 June 1994/Accepted: 30 March 1995 |
| |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ |
|
