Geology Facilities

The Division has apparatus capable of reproducing and maintaining for many hours the conditions where petrological processes occur, ranging from the surface of the earth to depths of about 650 kilometers. Conditions at much greater depths are studied (briefly) in the Caltech shock wave laboratory.

High-Temperature Furnaces

There are eight high-temperature furnaces dedicated to experimental petrology research. One, a graphite reducing-atmosphere furnace, is rated 3000°C, although it is normally operated with an Al2O3 muffle tube, limiting operations to < 1650°C. The others are molybdenum disilicide (MoSi2) furnaces with a useable temperature range of 900 to 1650°C and a silicon carbide (SiC) furnace usable to 1500°C. The furnaces are equipped with gas mixing capabilities, high-stability digital temperature controllers, programmed cooling and heating cycles, and solid electrolyte sensors for fO2 measurement.

High-Pressure Lab

The high-pressure laboratories contains a variety of apparati. There are 15 standard cold-seal pressure vessels, and ten with a novel design permitting rapid quench; these reproduce conditions of metamorphism and batholith emplacement corresponding to depths halfway through the continental crust. Two TZM pressure vessels reach higher temperatures appropriate for basic magmas. An intensifier producing a gas pressure of 1 GPa with an internally-heated pressure vessel provides the capability of investigating high- temperature magmatic processes through the depth range of the continental crust.

Piston-Cylinder Apparatus and Multianvil Devices

Conditions in the upper mantle are reproduced in the piston-cylinder and multianvil devices. The laboratory features three large presses equipped with piston-cylinder stacks for phase equilibrium experiments and mineral synthesis to 3.5 GPa and 1600°C. Our newest addition is a 1000-ton press with interchangeable cubic and octahedral multianvil devices for conditions from 3 to (perhaps) 25 GPa and temperatures to 2000 °C.

X-ray Fluorescence Spectrometer

The Bucholz Lab houses an XRF facility for the major and trace element analysis of geologic materials. The sample preparation lab include a Retsch planetary ball mill equipped with both agate and tungsten carbide grinding containers for powdering whole rock samples and a Claise Eagon 2 fluxer for fusing the powders into glass beads using lithium tetraborate as a flux. In addition, the lab contains a hydraulic press for making pressed powdered pellets. Glass pills and pressed pellets are analyzed using a 4 kW Zetium Panalytical X-ray fluorescence analyzer equipped with 6 analyzing crystals, a wavelength dispersive spectrometer, automated sample handler, and an integrated software system.

Other Facilities

Within the Division, there is a wide variety of optical microscopes for petrographic examination and photographic documentation as well as a wide range of supporting facilities for mineral synthesis and sample preparation and examination (e.g., ovens, welding equipment, micromachining equipment).

The scanning electron microscope, electron microprobe and infrared spectrometers are used routinely for study of the experimental samples. These facilities are being used for phase equilibrium studies of synthetic systems and natural rocks, fluid flow, kinetic studies, the intrinsic oxygen fugacities of minerals and rocks, and experimental partitioning studies on trace elements and stable isotopes.