Shelf and deep-sea sedimentation in Eocene forearc basin, western Oregon-fan or non-fan
The lower Eocene Tyee and Flournoy Formations in the southern and central Coast Range of Oregon contain unusual associations of shelf and deep-sea facies deposited in an elongate portion of a forearc basin. The sandstonerich nature and abrupt transition of sedimentary facies suggest that a variation of existing deep-sea fan models is present. The 6,500 ft (2,000 m) thick sequence calls for shelf sandstone virtually cascading into deep water along a line (shelf edge) rather than from a point source (submarine canyon) to feed a sand-rich system. Facies are described in terms of a sand-rich fan system. From south to north these facies include: deltaic, shelf, inner fan, mid-fan, outer fan, and basin plain. The deltaic facies contains coarse-grained, cross-bedded, distributary channel sandstone and interbedded coal. Some prograding deltaic sand extended to the edge of the narrow Eocene shelf and cascaded into the basin. Many complex, nested channels up to 1,200 ft (350 m) wide and 130 ft (40 m) deep were incised into fine-grained shelf and slope sediments at slope depths (line source).
- Research Organization:
- Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah
- OSTI ID:
- 6373714
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Vol. 67:11; ISSN AAPGB
- Country of Publication:
- United States
- Language:
- English
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ALLUVIAL DEPOSITS
CENOZOIC ERA
COASTAL REGIONS
CONTINENTAL MARGIN
CONTINENTAL SHELF
EARTH CRUST
FEDERAL REGION X
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC MODELS
GEOLOGIC STRUCTURES
GEOLOGY
NORTH AMERICA
OCEANIC CRUST
OREGON
PETROCHEMISTRY
PETROGRAPHY
ROCKS
SANDSTONES
SEDIMENTARY BASINS
SEDIMENTARY ROCKS
SEDIMENTATION
STRATIGRAPHY
TERTIARY PERIOD
USA