Advanced Signal Processing Analysis of Laser-Induced Breakdown Spectroscopy Data for the Discrimination of Obsidian Sources
JUNIATA COLL HUNTINGDON PA
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Obsidian is a natural glass of volcanic origin and a primary resource used by indigenous peoples across North America for making tools. Geochemical studies of obsidian enhance understanding of artifact production and procurement and remain a priority activity within the archaeological community. Laser-induced breakdown spectroscopy LIBS is an analytical technique being examined as a means for identifying obsidian from different sources on the basis of its geochemical fingerprint. This study tested whether two major California obsidian centers could be distinguished from other obsidian localities and the extent to which subsources could be recognized within each of these centers. LIBS data sets were collected in two different spectral bands 350 130 nm and 690 115 nm using a NdYAG 1064 nm laser operated at approx. 23 mJ, a Czerny-Turner spectrograph with 0.2-0.3 nm spectral resolution and a high performance imaging charge couple device ICCD detector. Classification of the samples was performed using partial least-squares discriminant analysis PLSDA, a common chemometric technique for performing statistical regression on high-dimensional data. Discrimination of samples from the Coso Volcanic Field, Bodie Hills, and other major obsidian areas in north-central California was possible with an accuracy of greater than 90 using either spectral band.
- Geology, Geochemistry and Mineralogy