Date of Award
Master of Science
The Stillwater Complex J-M reef, the only economic platinum deposit in the United States, consists of a 0.5 to 4 m-thick stratiform horizon of PGE-rich sulfides in an Archean layered mafic intrusion. The origin of this reef has been studied extensively using geochemical methods, yet remains highly debated. Dynamic magmatic processes have been virtually ignored in these geochemical studies. Magnetic methods provide a proven inexpensive approach to offer rapid, and reproducible results to deliver insight into these dynamic processes. I propose to investigate the variations of magnetic properties of layered rocks of the Stillwater Complex in the stratigraphic vicinity of the J-M reef. In this study, detailed magnetic methods were performed on a 115 ft core containing the J-M reef and adjacent rocks. A previously undiscovered cyclicity of magnetic susceptibility was found in the hanging wall and J-M reef section. Further tests were performed to determine the origin of the magnetic cycles. The footwall section lacked the magnetic properties seen in the J-M reef and hanging wall rocks. Both anisotropy of magnetic susceptibility, and high field magnetic data was collected at a high resolution interval along the core. It is possible that the results of this study can be used to constrain the origin of the ore body.
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