ZIRCON/FLUID TRACE ELEMENT PARTITION COEFFICIENTS MEASURED BY RECRYSTALLIZATION OF MUD TANK ZIRCON AT 1.5 GPA AND 800-1000°C
Previous experiments in our lab involved growth of zircon from the oxides in the presence of a trace element-doped fluid. Zircon crystals in run products were < 10 µm in diameter and were intermixed with unreacted oxides, so 20-30 µm diameter LA-ICP-MS spot analyses of crystalline run products produced mixed analyses. Analyses of collected solutes were used to calculate fluid composition, which combined with analyses of crystalline run products yielded Dz/f values that were highly variable for each experiment and showed little evidence of REE fractionation. Dz/f values calculated from fluid compositions and mass balance yield a subset of experiments with DLa/DLu similar to recrystallization experiments, with average Dz/f of 0.4 for La and 4.8 for Lu. With a few exceptions Th and U showed no significant fractionation in both types of experiments.