HANDHELD, X-RAY FLUORESCENCE INVESTIGATION OF MIDDLE-LATE DEVONIAN, PYRITIFEROUS, MILLBORO SHALE, SOUTHWESTERN VIRGINIA

The Millboro Shale is a ubiquitous lithologic unit in the Middle-Late Devonian stratigraphic architecture in Southwestern Virginia. The Millboro Shale extends through West Virginia, Virginia, Tennessee, Maryland and Pennsylvania and represents relatively shallow-marine accumulation of organic-carbon-rich sediment. Recent sedimentologic and organic and inorganic geochemical research has highlighted the non-uniform distribution of highly-pyritized intervals in this shale, with oxidative production of sulfuric acid posing a distinct threat to the local groundwater table.

The central hypothesis of this research was that a use of a state-of-the-art, portable, X-ray fluorescence (XRF) instrument, for measuring a full-spectrum of elements and their concentrations, in the field setting shows a statistically-significant, positive correlation with values obtained via the typical methodology of extracting a sample and conducting elemental concentration analysis of samples in the laboratory. If supported, data from this study will have important ramifications on utilization of emerging, portable XRF technology for a rapid, real-time, on-site analysis of black shale facies such as the Millboro Shale.

At a Millboro shale outcrop in Radford Virginia, researchers repelled down a ten meter outcrop and studied samples at ten centimeter intervals. Samples were first analyzed with the handheld XRF instrument, following which a sample was carefully extracted and catalogued. The data from the field measurements of these samples is being compared to the data generated from XRF analysis of elemental concentrations in the laboratory.

Results of this research will constitute an important first-step in evaluating both the applicability and reliability of such a hand-held, rapid XRF analysis of shales with heterogeneous mineralogy and sedimentology alike the Millboro Shale.