--> Abstract: Tectonics of the Cook Inlet, Alaska Revisited, by V. D. Ott, D. N. Malven, and R. C. Lanz; #91012 (1992).

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ABSTRACT: Tectonics of the Cook Inlet, Alaska Revisited

OTT, VALEN D., DOROTHY N. MALVEN, and ROBERT C. LANZ, Marathon Oil Company, Houston, TX

Previous tectonic studies in the Cook Inlet basin, Alaska, were published prior to recent advances in both plate tectonic theory and wrench fault modeling. In the last few years, new seismic and reinterpreted well data have made it possible to reinterpret basin structures in the light of modern tectonic concepts.

The 25 fields in the Cook Inlet have produced nearly 1.2 billion barrels of oil and 5.5 tcf of gas. Four fields alone account for just over 1 billion barrels of oil. The four largest gas fields account for over 5.2 tcf of gas. All of the production is from Tertiary reservoirs deposited since the Eocene in a subsiding forearc basin, filled with upwards of 30,000 ft of clastic sediments.

Basin development began in the early Tertiary when Mesozoic rocks of the Cook Inlet began to subside in a forearc setting as part of the larger accretionary complex along the southwest continental margin of Alaska known as the Peninsular Terrain. Continued deformation

along this active convergent margin resulted in a deep forearc basin filled mainly with coarse clastics eroded from surrounding highlands.

Pliocene-Pleistocene tectonism then deformed the basin by a series of right-lateral strike-slip faults and their associated folds. These folds often form positive "flower structure" traps for the oil and gas reserves found in the basin. Recent vintage seismic data combined with new interpretations of past drilling gives new insights into how the basin has evolved.

 

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