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Here is Nathan Zimmerman, a recent OSU Geology graduate. He used the OSU electron microprobe to understand the geochemistry of Himalayan tourmaline and was supported by a Wentz Fellowship.

This Wentz project relates Petrography to Structural Geology and Plate Tectonics. I am examining, with the electron microprobe recently donated to OSU, the chemical compositions of tourmaline grains in rocks collected from the Himalayas.  When ocean basins close and continental plates collide, mountains form, such as the Himalayas, and there is a great deal of stress from raised pressures and temperatures that get exerted on rocks of that region.  Tourmaline is a non-reactive, boron-rich mineral that is formed primarily when clays in shallow ocean basins are subjected to metamorphism.  Tourmaline’s chemical composition is able to keep intact under extremely large amounts of deformation associated with mountain-building processes.

The Main Central Thrust is a fault zone where the rocks show the most deformation associated with the formation of the Himalayan Range, and is one of the largest thrust faults depicted in the field. My faculty mentor, Dr. Elizabeth Catlos, has collected over 100 rock samples from transects that crosscut the Main Central Thrust and has arranged many of these samples on glass slides to be viewed by microscope. The total zone has accompanied nearly 500 km of slip in places, but the actual fault’s location differs on many geological maps.  By describing the tourmaline grains found in these rocks that have been collected near the Main Central Thrust, it is possible to better depict the location of the fault.  This fault zone may be responsible for the recent earthquakes in Northern India.

My objectives of this Wentz research project is following:

• Microscopically analyze and describe the appearance of tourmaline grains and other mineral grains associated with the fault. Descriptions will range from: size of the grains, shape of the grains, inclusions, rim features, fractures, core stability, associations, twinning, etc.

• Chemically analyze the composition of each tourmaline grain using the new electron microprobe donated to OSU by Phillips Petroleum.

• We expect that the rocks separated by the Main Central Thrust will have tourmaline grains that look distinct and are chemically different because the rock units experienced different geologic histories. I will then compile a report encompassing the descriptions and relate this to the geologic history of the Himalayas.

The goals of this project are all encompassing and I am working independently.  I have learned how to use the electron microprobe and accessories such as follows for preparations of the lab: ultrasonic bath, carbon-coater, analytical balance, optical microscope fitted with a digital camera, computer programs associated with the electron microprobe as well as any drafting programs such as Canvas 7 to aid my diagrams.  Dr. Catlos has arranged a space for me to work in her lab along with equipment, and I am highly motivated and excited to be working on this project.