Stratigraphy, petrology, and depositional environments of the Jarvis creek coalfield, Alaska

Abstract

Jarvis Creek basin coals are subbituminous, low in ash, and increase upsection in moisture, most major oxides and trace elements, and vitrinite with subsequent liptinite and inertinite decreases. Sulfide mineral deposits east-southeast of the basin are responsible for the enrichment of the upper coals in sulfur and metals. Sandstones are quartzose, arkosic, and lithic in the lower, middle, and upper units respectively, and were derived from a recycled orogen provenance. Sediment transport was from the south at the base, shifting to an easterly source higher in the section. Deposition was by braided and meandering streams on mid and distal portions of alluvial fans. The lower and middle units are correlative with the Healy Creek Formation, while the upper unit probably correlates with the Lignite Creek Formation. Measured, indicated, and inferred coal reserves are 17, 37, and 227 million short tons respectively, mostly in the upper unit at shallow depths.