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Summary of data on the age of the Orca Group, Alaska: A section in The United States Geological Survey in Alaska: Accomplishments during 1984

Circular 967
By: , , , , and 
https://doi.org/10.3133/70180306

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Abstract

The Orca Group is a widespread, thick, complexly deformed accretionary sequence of flysch and tholeiitic basalt in the Prince William Sound area (Winkler, 1976; Winkler and Plafker, 1981) (fig. 49). Despite a number of extensive field studies of the Orca Group, reliable data on the age of the unit have been elusive. On the basis of sparse paleontologic and radiometric data, the sequence was regarded as Paleocene and early Eocene(?) age (Winkler and Plafker, 1981). New paleontologic data from fossil localities shown in figure 49 suggest that some strata assigned to the Orca Group are of middle Eocene age and possibly as young as late Eocene or Oligocene. However, data suggesting an age younger than about 50 Ma appear to be incompatible with radiometrically determined ages for plutons that intrude the Orca Group.

Publication type Report
Publication Subtype USGS Numbered Series
Title Summary of data on the age of the Orca Group, Alaska: A section in The United States Geological Survey in Alaska: Accomplishments during 1984
Series title Circular
Series number 967
DOI 10.3133/70180306
Year Published 1985
Language English
Publisher U.S. Geological Survey
Publisher location Alexandria, VA
Contributing office(s) Alaska Science Center, Alaska Science Center Geology Minerals
Description 3 p.
Larger Work Type Report
Larger Work Subtype USGS Numbered Series
Larger Work Title The United States Geological Survey in Alaska: Accomplishments during 1984 (Circular 967)
First page 74
Last page 76
Country United States
State Alaska
Other Geospatial Orca Group
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