Discriminating volcanic centers with handheld laser-induced breakdown spectroscopy (LIBS)

Microcrystalline igneous rocks of volcanic origin, such as basalt or rhyolite, were a common source of prehistoric stone tools. This study explores the use of laser-induced breakdown spectroscopy (LIBS) as part of an effort to develop analytical tools to examine geological materials of archaeological interest. LIBS is a method of atomic emission spectroscopy capable of providing rapid, in situ elemental analysis of any material with minimal to no sample preparation. We have utilized both a bespoke laboratory system and a commercial handheld analyzer to acquire broadband LIBS emission spectra for fresh and unaltered volcanic samples of varying age and composition from two tectonic settings. The distinguishing chemical characteristics of the different volcanic regions and centers were identified and their sources differentiated through multivariate chemometric analysis. Classification and discrimination has been achieved with a high degree of success using a pattern recognition approach. These results suggest that the provenance of stone artifacts may be identified in the field using handheld LIBS through the use of algorithmic matching of LIBS emission spectra against a sufficiently robust and representative database previously prepared by analysis of samples of known origin.