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Published February 15, 2012 | public
Journal Article

Insights into the age of the Mono Lake Excursion and magmatic crystal residence time from (U-Th)/He and ^(230)Th dating of volcanic allanite

Abstract

We present new data for the age of the Mono Lake Excursion at its type locality. Using the (U-Th)/He system on allanite, we dated Wilson Creek Ash 15 (Lajoie, 1968) to 38.7 ± 1.2 ka (2 SE). The new age for this ash supports the hypothesis (Kent et al., 2002; Zimmerman et al., 2006) that the Mono Lake Excursion is coincident with, and probably the same event as, the Laschamp Geomagnetic Excursion (40.4 ± 2 ka), an event that shares similar magnetic characteristics with the excursion identified at Mono Lake. We also estimate an allanite magma residence time of slightly less than 30 ka based on ^(230)Th/^(238)U disequilibrium and the (U-Th)/He-based eruption age.

Additional Information

© 2011 Elsevier B.V. All rights reserved. Received 31 August 2011. Revised 13 December 2011. Accepted 15 December 2011. Available online 20 January 2012. Editor: B. Marty. We thank Gary Hemming and Guleed Ali for help with sampling and logistics, Lindsey Hedges and Adam Subhas for help with chemistry and analysis, and Becky Rudolph for assistance with the SEM. This research was supported by the Columbia Climate Center and the Comer Foundation, and by the National Science Foundation through a Graduate Research Fellowship to S. E. Cox.

Additional details

Created:
August 22, 2023
Modified:
October 17, 2023