Skip to main content
U.S. flag

An official website of the United States government

Subsurface stratigraphic picks of the Middle–Upper Triassic Shublik Formation, Alaska North Slope

Published by U.S. Geological Survey | Department of the Interior | Catalog Last Checked: August 01, 2026 at 05:37 AM | Dataset Last Updated: August 19, 2020 at 12:00 AM
The Middle–Upper Triassic Shublik Formation is the main source rock for Arctic Alaska oil and gas accumulations, including the supergiant Prudhoe Bay field. A revised stratigraphic framework recently has been developed in outcrop for the Shublik and related strata that delineates three large-scale stratigraphic units: 1) the lower clastic (LC) unit, 2) the middle carbonate-chert (MCC) unit, and 3) the upper clastic-carbonate (UCC) unit. The three stratigraphic units were interpreted to comprise five transgressive-regressive (T-R) sequences (LC1, MCC1, MCC2, MCC3, and UCC1). This outcrop-based framework has been extended to the subsurface of the Alaska North Slope using gamma-ray logs from 161 exploration wells. Subsurface stratigraphic picks of the five T-R sequences within the Shublik Formation for each well are documented herein.

Resources

2 resources available

Find Related Datasets

data.gov

An official website of the GSA's Technology Transformation Services

Looking for U.S. government information and services?
Visit USA.gov