Partitioning of Pb, Zn, W, Mo, CI, and major elements between aqueous fluid and melt in the systems granodiorite (granite, leucogranite)-H2O-NaCl-HCl
Chevychelov, V. Yu.; Chevychelova, T. K.
published: Sep 10, 1997
ArtNo. ESP154017201006, Price: 29.00 €
The partition coefficients K0 = C-fluid/C-melt of Pb, Zn, W, and Mo between aqueous fluid and melt were measured in the systems granodiorite-H2O-NaCl- HCl, granite-H2O-NaCl-HCl and leucogranite-H2O-NaCl-HCl at I and 5 kbars, 800-1000 °C and starting solution of 1 m NaCl +0.1 m HCl, with many reversed runs. We also determined the concentrations of SiO2, Al2O3, CaO, K2O, and Na2O in both phases of the systems studied and the concentrations of Cl in the melts. The silica concentration in the solution increases considerably with increasing CSiO2 in the coexisting melt. The concentrations of calcium, potassium and sodium in the solutions also correlate with the concentrations in the glasses. At 1 kbar chlorine is most soluble in granodioritic melt at 1000 °C (0.8-0.9 wt %). CCI decreases considerably in the granitic and leucogranitic melts. It also decreases with reduction of temperature to 850- 800 "C or with increasing pressure to 5 kbar. At I kbar, K0 fluid/melt of Pb and Zn can differ by a factor of 2-4 for different granitoid compositions and 1-2 orders of magnitude due to larger changes of melt composition from basaltic to granitic. Our data show very low contents (to n x 100 ppm) of tungsten and molybdenum in the granitoid melts studied. At 1 kbar Ko tluid/melt of W and Mo increase 2-3 times due to the change of the melt composition from granodioritic to granitic and leucogranitic.