Underlying much of New York, Pennsylvania, and West Virginia, the Marcellus Shale has gained a great deal of attention as the largest natural gas reservoir in the United States. However, despite the surge in gas drilling, little is understood about the processes that contributed to the formation and preservation of the organic-rich shale. The aim of my research is to identify the conditions and processes occurring in the western New York Marcellus Shale after its deposition.
Minerals within the shale are useful for paleo-reconstructions as they reflect the chemical environment in which they form. In my drill core samples, I find mineral assemblages that contain both barite (barium sulfate) and pyrite (iron sulfide). These mineral assemblages are unique because barite and pyrite form under different redox conditions (oxidizing vs. reducing). Sulfur isotope analysis of these sulfur-bearing minerals can reveal the mechanism and environment under which each mineral formed. Secondary ion mass spectrometry (SIMS) is a valuable technique as it not only allows us to measure our micron-sized minerals but also make in-situ measurements so that we may correlate any isotope value back to its specific mineral.
Through the generous support of the Alumni Research Award, I will measure in-situ the S isotopes of the barite and pyrite minerals at the NordSIMS Facility in Stockholm, Sweden. When understood along with other redox proxies, the S isotope composition of the sulfur-bearing minerals can provide valuable insight into the processes and redox conditions under which the shale was deposited.