Stratigraphy, depositional history, and reservoir potential of Cretaceous and early Tertiary rocks of Lower Cook Inlet, Alaska
Depositional relations within strata of Cretaceous age in the lower Cook Inlet area have been clarified by recent drilling and high quality seismic data. The Kaguyak Formation of Cape Douglas is expanded to include strata which range in age from Albian through Maestrichtian. Three members are proposed, which are (in ascending order) the Unnamed Albian-Cenomanian, the Middle Member, and the Saddle Mountain Member. Depositional relations within the Kaguyak Formation were strongly controlled by tectonic events and resultant basin configuration. The Unnamed Albian-Cenomanian Member (up to 1400 ft (425 m) thick) is composed of carbonaceous sandstone and shale and represents shallow to marginal marine deposition. The Middle Member is up to 4400 ft (1350 m) thick and consists of a southeastward-thickening wedge which is predominantly marine siltstone and claystone. Middle Member strata lap-up on and over-top a topographic shelf, which began to develop at about Turonian time and was a prominent feature in the area east of the Iniskin Peninsula by Campanian time. Significant shallowing at the beginning of Maestrichtian time was accompanied by an outpouring of coarse clastics of the Saddle Mountain Member. Up to 2000 ft (600 m) of mostly nonmarine sandstone, siltstone, and conglomerate extends seaward (south-eastward) to the shelf edge and is the only Cretaceous sandstone with reservoir potential in this area. Overlying and possibly continuous with the Saddle Mountain Member is a Paleocene sequence of sandstone and conglomerate named the Silver Salmon Formation. This formation showed the best reservoir properties of the Tertiary rocks in lower Cook Inlet.
- Research Organization:
- ARCO Alaska Inc., Anchorage
- OSTI ID:
- 6182940
- Report Number(s):
- CONF-8304200-
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Vol. 67:3; ISSN AAPGB
- Country of Publication:
- United States
- Language:
- English
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ALASKA
CENOZOIC ERA
CRETACEOUS PERIOD
DEPOSITION
FEDERAL REGION X
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC HISTORY
GEOLOGY
MESOZOIC ERA
MINERAL RESOURCES
NORTH AMERICA
PETROLEUM DEPOSITS
RESERVOIR ROCK
RESOURCE POTENTIAL
RESOURCES
STRATIGRAPHY
TERTIARY PERIOD
USA