--> Abstract: Geodynamic Subsidence Analysis as a Play Assessment Tool in the Alaskan Chukchi Sea, by J. K. Snow, G. Benevelli, N. Luise, and D. Prusak; #90096 (2009)

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Geodynamic Subsidence Analysis as a Play Assessment Tool in the Alaskan Chukchi Sea

J. Kent Snow, Giovanni Benevelli, Nicola Luise, and Deanne Prusak
Eni Petroleum, Houston, TX.

Based on the tectono-stratigraphic history of the Chukchi Sea, an assessment of several potential hydrocarbon plays was generated. Data included 2D seismic and wells in the Chuckchi supplemented by analogs from the North Slope and Sverdrup. Key plays are the Endicott, Lisburne, Ellesmerian, Jurassic, Cretaceous Kup C and Lower Brookian.

Integrated geoscience work focused on linking patterns of basin accommodation with geodynamic responses of isostatic, flexural, and thermal isostacy driven by tectonic loading, sediment loading, erosional unloading, asymmetric rifting, and flexural stiffness covarying with basal heatflow and lithospheric thickness. Significant points include the asymmetric geometries of Hanna Trough and Canadian Basin rifting, plate position of the Sverdrup, the extent of Jurassic erosion, and the foredeep setting of the Brookian.

Within this geodynamic framework we describe key events: The Paleozoic Hanna trough formed as an asymmetric rift divided into an upper plate, characterized by strong syn-rift isostatic uplift, strong post-rift thermal subsidence, and little post-rift flexural stiffness, and a lower plate, characterized by strong syn-rift isostatic subsidence, modest post-rift thermal subsidence and decreased flexural stiffness outboard of a mantle hinge-zone. During Jurassic rifting, a proto Barrow Arch rift-shoulder separated the Chukchi from the Sverdrup while the Canadian Basin opened as an asymmetric rift oriented perpendicular to the older Hanna Trough. Jurassic erosion is driven by synrift isostatic uplift within the upper plate and by flexural uplift along the proto Barrow Arch within the lower plate. During post-rift Kingak time, continued thermal and flexural subsidence provide accommodation for a transgressive sequence. The Brookian Orogeny begins with foredeep flexural accommodation filled by slope-wedge and shelfal prograding systems fringing a starved basin center. Forebulge erosion, along the Barrow Arch, leads to deposition of the Kup C. In the Middle Brookian, flexural unloading and uplift along the Harold Arch drives regional progradation. Upper Brookian Laramide inversion locally enhances lowstand erosion. Folds detached within the Lower Brookian shales result from both detached Brookian thrusts and basement inversion of older Hanna rift faults.


AAPG Search and Discover Article #90096©2009 AAPG 3-P Arctic Conference and Exhibition, Moscow, Russia