δ¹⁵N and Non-Carbonate δ¹³C Values for Two Petroleum Source Rock Reference Materials and a Marine Sediment Reference Material

By Kristin O. Dennen, Craig A. Johnson, Marshall L. Otter, Steven R. Silva, and Gregory A. Wandless

Samples of United States Geological Survey (USGS) Certified Reference Materials USGS Devonian Ohio Shale (SDO-1), and USGS Eocene Green River Shale (SGR-1), and National Research Council Canada (NRCC) Certified Marine Sediment Reference Material (PACS-2), were sent for analysis to four separate analytical laboratories as blind controls for organic rich sedimentary rock samples being analyzed
from the Red Dog mine area in Alaska. The samples were analyzed for stable isotopes of carbon (δ¹³C_ncc) and nitrogen (δ¹⁵N), percent non-carbonate carbon (Wt % C_ncc) and percent nitrogen (Wt % N).

SDO-1, collected from the Huron Member of the Ohio Shale, near Morehead, Kentucky, and SGR-1, collected from the Mahogany zone of the Green River Formation are petroleum source rocks used as reference materials for chemical analyses of sedimentary rocks. PACS-2 is modern marine sediment collected from the Esquimalt, British Columbia harbor.

The results presented in this study are, with the exceptions noted below, the first published for these reference materials. There are published information values for the elemental concentrations of “organic” carbon (Wt % C_org measured range is 8.98 - 10.4) and nitrogen (Wt % N_tot 0.347 with SD 0.043) only for SDO-1. The suggested values presented here should be considered “information values” as defined by the NRCC Institute for National Measurement Reference Materials and should be useful for the analysis of ¹³C, ¹⁵N, C and N in organic material in sedimentary rocks.