UNDERSTANDING THE C-S-FE SYSTEMATICS OF THE MARCELLUS FORMATION

The Marcellus Formation is both renowned and widespread across the Northern Appalachian Basin. Although the formation is widely known in the petroleum industry for its natural gas, there is still much to uncover about the formation’s paleoenvironment conditions that have contributed to it being such a valuable shale play. The formation is Middle Devonian in age and consists of three members arranged from oldest to youngest: Union Springs, Cherry Valley Limestone, and Oatka Creek. Both the youngest and oldest members consist of black shale, yet there is a discrepancy in the concentration of total organic carbon (TOC), with the younger Oatka Creek having considerably lower concentrations. The purpose of this study is to provide an explanation for the difference in TOC values between the two black shales by understanding the C-S-Fe systematics of the two black shale members. We measured TOC concentration using a Costech Elemental Analyzer (EA), and we obtained pyritic Fe (Fe_pyr) and S (S_pyr) using the Cr reducible technique. Since the destruction or preservation of organic matter is significantly correlated to the oxygen level at the time of deposition, high TOC values would indicate a favorable paleoenvironment for preservation – one that is anoxic/euxinic conditions and relies on anaerobic respiration (Fe limited) instead of aerobic respiration (Organic Matter Limited). Ultimately, this work will interpret whether or not oxygen conditions played a role in the observable difference between organic matter concentrations of the two black shale members.