| This dissertation reports the results of three projects involving high pressure experiments performed using a piston-cylinder apparatus. The first project investigates the genetic relationship between tourmaline-bearing granites of the Harney Peak suite in the Black Hills, South Dakota, and one of the Proterozoic schists (HP-60-1) these granites intrude. The second project delineates the thermal gradient along the vertical axis of the CaF2 furnace assembly used in high temperature piston-cylinder experiments. The third project assesses the effects of variable mode on the melting systematics of fertile peridotitic assemblages.; Experiments for the second project were conducted at 10 kbar using two thermocouples, and typically did not contain a sample capsule. For the first and third projects, experiments were conducted at 10 kbar over a range of temperatures (∼812–1390°C) on finely ground rock samples contained in either gold or graphite-lined platinum capsules. Run durations varied from 2 to 18 days, depending on the rock type and temperature. The phase proportions in each run product were determined from electron microprobe analyses of the phases produced and mass balance. From trends in changing phase proportions with increasing melt fraction, muscovite and biotite dehydration-melting reactions for HP-60-1, and seven peridotite melting equations for lherzolite, wehrlite, and harzburgite assemblages were determined.; For the first project revealed HP-60-1 is too Ti-rich and did not produce enough melt to be a likely source rock for the tourmaline-bearing granites of the Harney Peak suite. In the second project, experiments determined that the thermal peak within the furnace assembly is displaced upward from the furnace center, due to the low thermal conductivity of a stainless steel plug placed on top of the assembly. The third project showed that variations in mode profoundly affect the melting reactions, compositions of melt, and notably the melt productivity of peridotitic assemblages.; This dissertation includes co-authored material, both previously published and currently in review. |
