CHARACTERIZING UTICA SHALE DEPOSITIONAL PROCESSES USING PORTABLE XRF ANALYSES AND POSITIVE MATRIX FACTORIZATION

Elemental concentrations from the Utica Shale were obtained from a drill core in central New York using portable x-ray fluorescence (pXRF). Three separate samples were analyzed over 0.25-meter increments and the pXRF results were averaged to obtain concentrations and associated analytical error for 29 elements. The resulting 350 analyses and the associated error were used as the input parameters for the Environmental Protection Agency: Positive Matrix Factorization (PMF) receptor model. The PMF model was developed for atmospheric particulate matter studies but also can be adapted in geoscience applications to calculate and plot factor contributions over a time series. PMF returned a best fit 8 factor solution that included contributions from carbonates (Ca, Mn, Fe), shale (Si, Al, Mg), organic-rich black shale (V, Ni, Cu, Zn, Mo), sulfides (S, Fe, As, Mo), diagenetic processes (Ca, Sr) and three lesser factors that could be indicators of sediment provenance. When the PMF calculated output factors are plotted, depositional processes can be interpreted that correspond with lithologic facies that have been described from this core using traditional techniques. Future work will include interpretation from coupled PMF and pXRF analyses from other cores to better characterize sediment provenance and basin evolution for the Utica Shale.