Thermal maturity of northern Appalachian Basin Devonian shales: Insights from sterane and terpane biomarkers

► Northern Appalachian Basin Devonian shales are an important source rock. ► Vitrinite reflectance underestimates thermal maturity in early mature Devonian shale. ► Misidentification of solid bitumen as vitrinite may be a significant problem. ► Biomarker ratios suggest most samples are mature with respect to hydrocarbon generation.