A seismic stratigraphic and structural interpretation of the middle Paleozoic Ikpikpuk-Umiat Basin, National Petroleum Reserve in Alaska

Abstract

The Ikpikpuk-Umiat Basin is located in the eastern NPRA in northern Alaska. The basin overlies the eroded remnants of a Middle Devonian folded belt and contains up to 18, feet of Late Devonian and Mississippian elastics and up to 8 feet of Mississippian and Pennsylvanian carbonates. These sediments were deposited in two depocenters, an older larger depocenter in the southeast primarily composed of the clastic sequence and a younger, smaller depocenter in the northwest predominantly filled with the carbonate sequence. The sediments in the southeastern depocenter were deposited while the basin was undergoing subsidence and extension whereas sediments in the northwest depocenter were deposited during 8n intra-Mississippian compressional event which affected the entire basin. This compressional event is characterized by north vergent thrust faults trending west-northwest across the basin. A number of these thrust faults are reactivated earlier down-to-the-basin normal faults. The Ikpikpuk-Umiat Basin is tentatively interpreted to be part of an A-subduction related backarc region analogous to the Pannonian Basin in Hungary.