--> Abstract: Three-Dimensional Foreland Basin Stratigraphic Geometry and Subsidence History: Colville Trough, Alaska, by P. B. Flemings; #91012 (1992).

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ABSTRACT: Three-Dimensional Foreland Basin Stratigraphic Geometry and Subsidence History: Colville Trough, Alaska

FLEMINGS, P. B., Massachusetts Institute of Technology, Boston, MA, et al.

Cretaceous Brookian strata in the Colville Trough (Alaska) are dominated by two progradational cycles that are controlled by thrust-induced subsidence in the Brooks Range to the south. We have mapped 15 stratigraphic surfaces, within Cretaceous strata, across the National Petroleum Reserve and the Arctic Slope. The two major depositional cycles are early Hauterivian to late Albian in age (comprising the HRZ, Torok, and Nanushuk formations), and base Cenomanian through Maastrichtian in age (comprising the Seabee and Schrader Bluff formations). Each cycle is composed of a lower retrograding section and an upper prograding section. Successive shelf margins in the progradational packages have a north-northwest to south-southeast orientation within the Colville Trough and indicate a strong west-to-east sediment transport component. Downlap surlaces in front of the prograding shelf record paleobathymetries that range from hundreds of feet along the Barrow arch to over 5000 ft adjacent to the foothills of the Brooks Range.

One- and two-dimensional (flexural) subsidence analyses reveal that the retrogradational record of these two depositional cycles corresponds to times of rapid basin subsidence that resulted in paleobathymetries far greater than could result from global sea-level change. Accurate paleobathymetries and subsidence analyses that account for regional (flexural) isostatic compensation are critical to determining the locations and magnitudes of thrust-driven subsidence. The Hauterivian-aged retrogration records the more dominant subsidence event (thousands of meters). This event was felt throughout the study area, but increased to the south and west, suggesting thrust-induced subsidence was greatest in the western Brooks Range. The subsidence event corresponding to early Cenomanian flooding as much smaller (~750 ft), yet also increases toward the thrust belt and implies thrust-induced loading in the Brooks Range.

 

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)