Cosmogenic 3He and 21Ne production rates calibrated against 10Be in minerals from the coso volcanic field

Amidon, W.H., Rood, D.H. and Farley, K.A. (2009) Cosmogenic 3He and 21Ne production rates calibrated against 10Be in minerals from the coso volcanic field. Earth and Planetary Science Letters, 280(1-4), pp. 194-204. (doi: 10.1016/j.epsl.2009.01.031)

Abstract

This study calibrates the production rate of cosmogenic 3He in pyroxene, olivine, garnet, zircon and apatite as well as 21Ne in quartz and pyroxene against the known production rate of 10Be in quartz. The Devil's Kitchen rhyolite from the Coso volcanic field in southeastern California (elev. ~ 1300 m) was chosen for this study due to its young age (~ 610 ka) and diverse mineral assemblage. Based on 10Be, our two rhyolite samples have apparent exposure ages of ~ 49 and 93 ka, indicating substantial erosion after eruption. Combining data from the two samples, we estimate sea level high latitude 3He spallation production rates of 145 ± 11, 141 ± 16, and 144 ± 30 at g− 1 a− 1 (2σ) for pyroxene, olivine and spessartine garnet respectively. For zircon and apatite, we estimate apparent 3He spallation production rates of 114 ± 8 and 149 ± 28 at g− 1 a− 1 (2σ) respectively. The rates for zircon and apatite are reported as apparent production rates because we do not explicitly address the redistribution of spallation produced 3He from adjacent minerals. These estimates quantitatively account for production of 3He from both cosmogenic and radiogenic neutron reactions on 6Li within the analyzed phases and also implanted from nuclear reactions in neighboring minerals; the high U, Th and Li content of this rhyolite provides a particularly rigorous test of this correction. We estimate 21Ne production rates of 17.7 ± 1.6 and 34.1 ± 3.2 at g− 1 a− 1 (2σ) in quartz and pyroxene (Fe/Mg = 0.7 by mass) respectively. Although high U and Th contents create the potential for significant production of nucleogenic 21Ne, this component is small due to the young eruption age of the rhyolite.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Rood, Dr Dylan
• Authors: Amidon, W.H., Rood, D.H., and Farley, K.A.
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Earth and Planetary Science Letters
• ISSN: 0012-821X
• Published Online: 25 February 2009