SOURCE-ROCK POTENTIAL OF THE LOWER CRETACEOUS PEBBLE SHALE UNIT, NORTHEASTERN ALASKA.

In northeastern Alaska, the Lower Cretaceous pebble shale unit (PSU) was investigated for source-rock potential along the west side of the Canning River (outside of ANWR), along an unnamed tributary east of the Katakturuk River (Boulder Bowl), and at Marsh Creek. Samples were collected and analyzed for total organic carbon (TOC), Rock-Eval, and vitrinite relectance (Ro). Results indicate that there are 12- to 31-m-thick packages of the PSU that have suficient organic content (2-6 wt. percent TOC) to constitute good to excellent source rock. However, Rock-Eval data from these same samples suggest poor source-rock quality (Hydrogen Index [HI] < 50mg Hydrocarbon [HC]/g TOC) likely from elevated thermal maturity of the PSU as indicated by high Tmax and Ro values. The average vitrinite relectance of the sections sampled for this study ranges from 1.28 to 1.79 percent Ro, indicating latest oil window to gas window maturity. Results from this study are consistent with previous studies indicating that the PSU originally had good source-rock potential; however, because of advanced thermal maturity in the study area, the parameters that correspond to source-rock quality indicate considerable degradation. [ABSTRACT FROM AUTHOR]