### Age of the youngest volcanism at Eagle Lake, northeastern California—40Ar/39Ar and paleomagnetic results

By: Michael A. Clynne**Andrew T. Calvert**Duane E. Champion**L. J. P. MufflerMichael G. Sawlan**Drew T. Downs

                            https://doi.org/10.3133/ofr20171027

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#### Abstract

First posted March 22, 2017

**For additional information, contact:**
Volcano Science Center—Menlo Park U.S. Geological Survey 345 Middlefield Road, MS 910 Menlo Park, CA 94025https://volcanoes.usgs.gov/

The age of the youngest volcanism at Eagle Lake, California, was investigated using stratigraphic, paleomagnetic, and 40Ar/39Ar techniques. The three youngest volcanic lava flows at Eagle Lake yielded ages of 130.0±5.1, 127.5±3.2 and 123.6±18.7 ka, and are statistically indistinguishable. Paleomagnetic results demonstrate that two of the lava flows are very closely spaced in time, whereas the third is different by centuries to at most a few millennia. These results indicate that the basalt lava flows at Eagle Lake are not Holocene in age, and were erupted during an episode of volcanism at about 130–125 ka that is unlikely to have spanned more than a few thousand years. Thus, the short-term potential for subsequent volcanism at Eagle Lake is considered low. 

#### Suggested Citation

Clynne, M.A., Calvert, A.T., Champion, D.E., Muffler, L.J.P., Sawlan, M.G., and Downs, D.T., 2017, Age of the youngest volcanism at Eagle Lake, northeastern California—40Ar/39Ar and paleomagnetic results: U.S. Geological Survey Open-File Report 2017–1027, 24 p., https://doi.org/10.3133/ofr20171027.

ISSN: 2331-1258 (online)

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#### Table of Contents

Abstract Introduction General Geology of the Eagle Lake Area Previous Map Depiction of the Young Basalts at Eagle Lake Unit Descriptions Paleomagnetic Secular Variation40Ar/39Ar Results Discussion Conclusions Acknowledgments References Appendix 1. 40Ar/39Ar Analytical Techniques Appendix 2. Tabulated 40Ar/39Ar data for basaltic flows of Eagle Lake

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