Identifier

etd-11112016-061044

Degree

Master of Science (MS)

Department

Geology and Geophysics

Document Type

Thesis

Abstract

Tourmaline is a petrologic indicator mineral that is the major repository of boron in the earth’s crust. It forms readily when boron is present, accommodating multiple cations and anions with multiple possible substitutions for each site in the crystal structure. It is stable over a wide variety of pressures and temperatures, from near-surface P/T conditions to greater than 950 C and 7 GPa. It records information about conditions of formation, as well as pressure and temperature. Due to its resistance to chemical or physical weathering, and the negligible diffusion of elements in the crystal lattice, information about provenance is preserved. In Henry and Guidotti (1985), major elements of tourmaline were used to construct ternary diagrams that classify tourmalines according to provenance. However, this technique does not make use of the entirety of available chemical data. New statistical techniques can make use of all available chemical information and provide information about element importance. Using a novel application of an existing statistical method, random forests, to high-dimensional tourmaline data, provenance information is obtained. Existing chemical analyses are assembled into a database and labeled with their provenance. A random forest is ‘grown’ using a full database of tourmaline data, producing a set of rules for classifying tourmalines according to provenance. The random forest method has internal controls on accuracy and fitting of the data, and is capable of classifying tourmalines at a level of between 90 and 95% accuracy. As an independent test, a random forest built from this database is used to successfully classify tourmalines according to provenance.

Date

2016

Document Availability at the Time of Submission

Secure the entire work for patent and/or proprietary purposes for a period of one year. Student has submitted appropriate documentation which states: During this period the copyright owner also agrees not to exercise her/his ownership rights, including public use in works, without prior authorization from LSU. At the end of the one year period, either we or LSU may request an automatic extension for one additional year. At the end of the one year secure period (or its extension, if such is requested), the work will be released for access worldwide.

Committee Chair

Henry, Darrell

DOI

10.31390/gradschool_theses.4490

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