Application and limitations of the authigenic 10Be/9Be dating and meteoric 10Be inventory in Bouse Formation along the lower Colorado River corridor, southwestern USA

Ara Jeong; Yeong Bae Seong; Brian F. Gootee; Byung Yong Yu; Suet Yi Cheung

doi:10.18814/epiiugs/2022/022018

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Episodes 2023; 46(1): 85-97

Published online March 1, 2023

https://doi.org/10.18814/epiiugs/2022/022018

Application and limitations of the authigenic ¹⁰Be/⁹Be dating and meteoric ¹⁰Be inventory in Bouse Formation along the lower Colorado River corridor, southwestern USA

Ara Jeong¹, Yeong Bae Seong^2*, Brian F. Gootee³, Byung Yong Yu⁴, Suet Yi Cheung⁵

¹ Department of Civil Engineering and Environmental Sciences, Korea Military Academy, Seoul 01805, Republic of Korea
² Department of Geography Education, Korea University, Seoul 02841, Republic of Korea
³ Arizona Geological Survey, 1955 East 6th Street, Tucson, Arizona 85704, USA
⁴ AMS Laboratory, Advanced Analysis Center, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
⁵ Department of Parks, Recreation and Tourism Management, North Carolina State University, Raleigh, NC 27695, USA

Correspondence to:E-mail: ybseong@korea.ac.kr

Received: December 1, 2021; Revised: May 11, 2022; Accepted: May 11, 2022

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Authigenic ¹⁰Be/⁹Be dating and ¹⁰Be inventory methods have been used as a robust chronological tool to date oceanic sediments as old as ~12 Ma. However, their application was limited to continental sediments deposited in relatively closed lakes. We tested the two methods to examine their applicability to early-Pliocene Bouse Formation in the lower Colorado River corridor, as its stratigraphy and age are well-constrained. The calculated authigenic ¹⁰Be/⁹Be ages for the Bouse Formation range from 2.51 to 3.85 Ma, with a mean age of 3.15 Ma, which is considerably younger than the published ages of 5.4 to 4.7 Ma. The measured ¹⁰Be inventory was three orders of magnitude lower than the predicted inventory. We examined the factors that may constrain the behavior of beryllium isotopes and suggest that the offset of age could be derived from an estimated initial ratio that may not be the real one or the incomplete retentivity of the beryllium isotopes. The discrepancy between predicted and measured ¹⁰Be inventory may be due to surface erosion, insufficient ¹⁰Be retention or inaccurate estimation of ¹⁰Be inheritance.