HR: 0800h
AN: V41C-1404    [Abstracts]
TI: Preliminary Experiments and Determination of the Thermal Gradient in a 12.7 mm CaF$_{2}$ Furnace Assembly, Humboldt State University Piston-Cylinder Laboratory
AU: * Schwab, B E
EM: schwab@humboldt.edu
AF: Humboldt State University, Department of Geology, Arcata, CA 95521 United States
AB: A 12.7 mm piston-cylinder laboratory has been established at Humboldt State University. A series of double-thermocouple (DTC) experiments were performed to measure the thermal profile of the furnace assembly following the procedures of Pickering et al. (1998, Amer. Min.). Furnace assemblies consist of a 304 stainless base plug, CaF&_{2}$ sleeve, straight-walled graphite heater tube, crushable MgO inner parts, and lower graphite plug and ring which allow for extrusion of the graphite heater tube during shortening of the sleeve and MgO pieces. Careful measurement of pre- and post-run assembly parts indicate an average 30-$35%$ shortening of the assembly. DTC results show a thermal peak that is displaced $\sim$2.0 mm above the center of the effective furnace, defined as the length of inner MgO pieces post-run. This offset is in the same direction (upward, toward base plug), but slightly less than the offset described by Pickering et al. (1998). A secondary measure of the thermal profile using spinel growth via reaction between MgO and Al$_{2}$O$_{3}$ assembly parts (e.g., Watson et al., 2002, CMP) is underway. A single partial melting experiment was performed at 1.0 GPa and $1330\deg$C for 72 hours using intermediate peridotite starting material INT-A in a graphite-lined Pt capsule with vitreous carbon spheres as a melt sink. Phase compositions were determined by electron microprobe and mass balance calculations were made to determine melt fraction and mineral mode. Initial calculations yield glass:olivine:cpx:opx:spinel proportions of: 5.0:54.2:15.9:23.9:1.1. These preliminary results correspond well with previous work performed at the University of Oregon on the same starting material (Schwab and Johnston, 2001). The best match is with a $1315\deg$C experiment (INT-A13) in terms of mode (6.9:53.7:13.4:25.0:1.0) and glass composition, indicating that the temperature of this initial experiment may be slightly cooler than the target temperature, however the results of this interlaboratory comparison are still within the $\pm$10-$15\deg$C temperature uncertainty of the piston cylinder apparatus. Additional calibration experiments are ongoing.
DE: 3630 Experimental mineralogy and petrology
DE: 3640 Igneous petrology
DE: 3694 Instruments and techniques
DE: 1025 Composition of the mantle
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting