Parameterization of the Fe = Mg exchange coefficient (Kd) between clinopyroxene and silicate melts

Compilations of experimental data allow the clinopyroxene Fe = Mg exchange equilibrium constant (Kd = (XFe/XMg)Clinopyroxene / (XFe/XMg)Melt) to be parameterized. Values of Kd increase with increasing pressure, temperature, Log fO2, melt CaO, NBO/TO, LnMgO, MgO#; and with decreasing melt SiO2, and Na2O + K2O. Multiple regression analysis yields improved fits, including some based solely on mineral compositional data. These parameterizations allow improved petrogenetic hypothesis testing for clinopyroxene-bearing assemblages.