NONDESTRUCTIVE SOURCING OF GRANITE GROUND STONE TOOLS FROM BELIZE USING PXRF

Current research on portable x-ray fluorescence (pXRF) technology has shown improvements in calibration standards and accuracy of results. With these advances comes the ability to use pXRF on materials beyond homogeneous artifacts made of chert, obsidian, and basalt, which have previously been the focus of the majority of pXRF work in geoarchaeology. The primary goals of this project are to assess the ability of pXRF to accurately and precisely develop geochemical fingerprints of heterogeneous materials, specifically granite, and to assess the ability of pXRF to distinguish between the three plutons within the Maya Mountains of Belize. This study examines the ability of pXRF to be used for geochemical sourcing studies on granite manos and metates in Belize. There are three petrographically, but not visually, distinct granitoid plutons in the Maya Mountains: Mountain Pine Ridge, Cockscomb Basin, and Hummingbird Ridge. These igneous regions are isolated from one another and from any other igneous deposits, making it an ideal case study for this project. Outcrop samples were collected during the summer of 2013 and 2014 in order to obtain a representative sample of the variation within and between the plutons. In order to examine the accuracy and precision of pXRF a combination of thin section petrography, XRF, pXRF, and laser ablation ICP-MS will be employed on all outcrop samples. Each sample is analyzed and corrected with respect to data obtained from pXRF readings on international granite standards in order to increase the quantitative aspect of this research. During the summer of 2014 pXRF data was collected on granitic artifacts from multiple sites throughout Belize in order to correct for potential exchange biases incurred by communities that are located further from one pluton than another. Preliminary results on the outcrop samples indicate that pXRF data is able to differentiate between plutons. In addition to separating outcrop samples, this work implies that pXRF can match artifact geochemistry to outcrop fingerprints. This will allow for possible locating of source regions and production sites within and near the mountains as well as a more thorough reconstruction of ancient exchange patterns.