Timing of early Tertiary ridge subduction in southern Alaska: A section in Geologic studies in Alaska by the U.S. Geological Survey, 1992

Bulletin 2068
By: , and 

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Abstract

We present a new compilation of 158 isotopic ages from Tertiary plutons that intrude the accretionary prism (Chugach-Prince William composite terrane) of southern Alaska. Two broad plutonic age groups are present: Paleocene to Eocene (the Sanak-Baranof plutonic belt), and Oligocene to Miocene. Plutons of the Sanak-Baranof belt are broadly coeval with magmatism along the axis of an Andean-type arc that lay farther inboard. A plot of age versus position along strike shows that near-trench magmatism progressed from about 66-63 Ma in the west to about 50 Ma in the east. We interpret the near-trench magmatism as the product of subduction of the Kula Farallon ridge (or another unidentified spreading center) and suggest that the age progression tracks a migrating trench-ridge-trench triple junction along the continental margin.

Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title Timing of early Tertiary ridge subduction in southern Alaska: A section in Geologic studies in Alaska by the U.S. Geological Survey, 1992
Series title Bulletin
Series number 2068
DOI 10.3133/70180223
Year Published 1993
Language English
Publisher U.S. Government Printing Office
Publisher location Washington, D.C.
Contributing office(s) Alaska Science Center Geology Minerals, Alaska Science Center, Central Mineral and Environmental Resources Science Center
Description 15 p.
Larger Work Type Report
Larger Work Subtype USGS Numbered Series
Larger Work Title Geologic studies in Alaska by the U.S. Geological Survey, 1992 (Bulletin 2068)
First page 163
Last page 177
Country United States
State Alaska