Skip to Main Content
Book Chapter

Reevaluation of the timing and duration of extrusion of the Imnaha, Picture Gorge, and Grande Ronde Basalts, Columbia River Basalt Group

By
Ajoy K. Baksi
Ajoy K. Baksi
Search for other works by this author on:
Published:
January 01, 1989

The K-Ar data for various sections of the Columbia River basalt (Imnaha, Picture Gorge, and Grande Ronde Basalt formations) have been reevaluated, utilizing the atmospheric argon contents of the rocks to identify the least altered samples. These ages, together with the results of paleomagnetic studies on these same sections, were then fitted into the known magnetostratigraphy of the Columbia River basalt. Finally, these findings are integrated with the geomagnetic polarity time-scale for mid-Miocene times. The Imnaha Basalt was formed ~17.2 Ma, and the Picture Gorge Basalt ~ 16.0 Ma. The Grande Ronde Basalt was extruded between ~16.9 and 15.6 Ma, with >50 percent of the total volume (magnetostratigraphic units R2–N2) formed within ~300,000 yr, around 15.8 Ma.

You do not currently have access to this article.

Figures & Tables

Contents

GSA Special Papers

Volcanism and Tectonism in the Columbia River Flood-Basalt Province

Stephen P. Reidel
Stephen P. Reidel
Search for other works by this author on:
Peter R. Hooper
Peter R. Hooper
Search for other works by this author on:
Geological Society of America
Volume
239
ISBN print:
9780813722399
Publication date:
January 01, 1989

References

Related

Citing Books via

Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal