| Summary: | The Ikpikpuk-Umiat basin of Alaska's North Slope accumulated ~ 30,000' of clastic and carbonate strata during regional extension or transtension from the Late Devonian-Permian. However, this investigation confirms that low-intensity compressional shortening formed east-west trending fault propagation folds in addition to north-south trending flower structures recorded during upper Endicott Group and Lower Lisburne Group deposition. Mapping biostratigraphically age constrained horizons on reprocessed 2D NPRA seismic profiles provide a method for dating the deformation. This research reveals that the Ikpikpuk-Umiat basin experienced a local stress field inversion from 349-299 Ma prior to Triassic drifting. Observations from this work suggest that this synrift localized inversion propagated through the basin from east to west. Either a rotation in the direction of extension/transtension (causing strain partitioning), or a two stage basin formation (extension followed by a shear propagating through the basin) resulted in low-intensity thrusting recorded from the late Mississippian through the Pennsylvanian. San Diego State University
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