Bedrock geologic map of the National Petroleum Reserve in Alaska
This chapter is an introduction with background information to accompany the bedrock geologic map (pl. 8.1) and cross sections (pl. 8.2) of the National Petroleum Reserve in Alaska (NPRA). Unconsolidated Tertiary( ) and Quaternary sediments, principally those of the Pliocene( ) and Pleistocene Gubik Formation and the Holocene deposits, are omitted from the map in the northern part of the area in order to show the approximate subcrop contacts between consolidated rock units that are Tertiary and older in age. These contacts are approximated from information on the first consolidated rock unit drilled in oil exploration wells and from maps of shallow seismic results in the northern and eastern parts of the NPRA. Modifications to earlier geologic maps have been made where warranted by more recent geologic investigations. Previous geologic compilations of the southern part of the NPRA have been partly remapped to conform to the tectonostratigraphic units named by Ellersieck and others and Mayfield and others. In the northwestern part of the reserve, rocks previously mapped as part of the Colville Group are here reassigned to the Nanushuk Group. Reports of plant fossils on the Kuk and Kaolak Rivers and micropaleontologic study of near-surface strata at the Tunalik No. 1 well indicate that the rocks west of the Meade River are probably all pre-Turonian in age and therefore older than any known rocks in the Colville Group. This revision is consistent with the sedimentology, because both the Nanushuk and Colville Groups consist of deltaic sediments that were prograded across the North Slope from south-west to northeast. Through Colville deposition began with a significant marine transgression, it seems unlikely that this deposition reached as far west as the area in question.
- OSTI ID:
- 6844194
- Journal Information:
- United States Geological Survey, Professional Paper; (USA), Journal Name: United States Geological Survey, Professional Paper; (USA)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ALASKA
STRATEGIC PETROLEUM RESERVE
RESERVOIR ROCK
DEPOSITION
EXPLORATORY WELLS
FOSSILS
GEOLOGIC FORMATIONS
GEOLOGY
MAPPING
MAPS
PALEONTOLOGY
SEDIMENTARY ROCKS
SEDIMENTATION
SEISMIC SURVEYS
STRATIGRAPHY
TECTONICS
FEDERAL REGION X
GEOPHYSICAL SURVEYS
NORTH AMERICA
RESERVES
RESOURCES
ROCKS
SURVEYS
USA
WELLS
020200* - Petroleum- Reserves
Geology
& Exploration