Material transport in laser‐heated diamond anvil cell melting experiments

Olivine from San Carlos, Arizona, Fa0.093 was compressed in a diamond anvil cell and melted under the action of a Nd: YAG laser. Stripes of melted material were formed by scanning the sample under the laser. Scanning electron microscopy and x‐ray microanalysis of the recovered samples reveal large‐scale (∼100 μm) transport of material through the sample, caused by the laser‐induced melting. Early‐crystallizing phases form at the beginning of the laser‐melted stripe; incompatible elements and late‐crystallizing phases are concentrated at the end of the stripe. This behavior is exploited to determine melting behavior of high‐pressure silicate assemblages of olivine composition. At pressures where β‐spinel is the phase melted, relative strengths of partitioning can be estimated for the incompatible elements studied. Iron was found to partition into the melt from β‐spinel less strongly than calcium, and slightly more strongly than manganese. At higher pressures, where a silicate perovskite/magnesiowüstite assemblage is melted, it is determined that silicate perovskite is the liquidus phase, with iron‐rich magnesiowüstite accumulating at the end of the laser‐melted stripe.