A procedure for calculating the equilibrium distribution of trace elements among the minerals of cumulate rocks, and the concentration of trace elements in the coexisting liquids
Bedard Jean, H.
Chemical Geology 118(1-4): 143-153
Whole-rock trace-element analyses can be used in conjunction with partition coefficients and mineral modes to calculate a liquidus-temperature equilibrium distribution of trace elements among the constituent minerals of cumulate rocks. Once the concentration of a trace element in a given mineral phase is known, then the trace-element concentration in the liquid that was in equilibrium with this mineral can be calculated if certain assumptions are made about the temperature and major-element chemistry of the liquid. The effects of a trapped melt fraction (TMF) are accounted for by: (1) including in the calculation a phase (the trapped melt) with a mineral/melt partition coefficient of 1; and (2) adjusting the rock's mode to reflect removal of the TMF. The method yields results comparable to those given by mineral separation or in situ analysis for trace elements.