COMPARISON BETWEEN WHOLE ROCK LITHOGEOCHEMISTRY AND FINE LITHOGEOCHEMISTRY OF MARCELLUS SHALE

The Marcellus Shale is a geological formation well known not only for being rich in natural gas but also for its high concentrations of uranium and other heavy metals. Drilling and fracking operations may alter pH and Eh conditions and cause changes in the solubility and mobilization of these metals. The goal of this project is to identify the concentrations of heavy metals in different size fractions of the Marcellus Shale. To reach this goal, 25 samples of Marcellus Shale, 14 outcrops and 11 cores, have been collected, crushed, and sieved to less than 125 µm. Then, through centrifugation, clays (< 2 µm) have been separated from the rest of the sediments. Whole rock lithogeochemistry and separated fine sediments have been analyzed by INAA (Instrumental Neutron Activation Analyses). The analysis for the whole rock have shown, for example, average concentrations of As, Co, Cr, U of 28.95, 20.42, 79.96, 19.63 ppm respectively. The results of lithogeochemistry of the fine sediments are pending. A statistical comparison of the bulk and fine metal concentrations will be completed.