Potassium-argon ages of basement rocks from Saint George Island, Alaska

D.M. Hopkins; M.L. Silberman

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USGS · 70232571

Potassium-argon ages of basement rocks from Saint George Island, Alaska

D.M. Hopkins·M.L. Silberman

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Abstract

Potassium-argon ages from basement granitic rocks that intrude serpentinized peridotite on St. George Island, Alaska, range from 50 to 57 million years, with an initial argon isochron age. interpreted as a minimum figure, of 52 ± 2 m.y. The age of the granitic rocks and their association with serpentinized peridotite near the continental margin, which apparently marks the site of a Mesozoic subduction zone, suggest that the position of the subduction zone shifted southward to the Aleutian Trench in early Tertiary time.

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Journal of Research of the U.S. Geological Survey Article

Source-reported bounding extent: 56.515563731608296° to 56.63357434738749° latitude; -169.78271484375° to -169.45037841796875° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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D.M. Hopkins, M.L. Silberman. 1978. Potassium-argon ages of basement rocks from Saint George Island, Alaska. https://pubs.usgs.gov/publication/70232571

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