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Zircon age and oxygen isotopic correlations between Bouse Formation tephra and the Lawlor Tuff

Harvey, Janet C. (2014) Zircon age and oxygen isotopic correlations between Bouse Formation tephra and the Lawlor Tuff. Geosphere, 10 (2). pp. 221-232. ISSN 1553-040X. http://resolver.caltech.edu/CaltechAUTHORS:20140807-091535811

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Abstract

The Bouse Formation in the lower Colorado River trough holds an important record of the onset of the modern drainage patterns in the southwestern United States. It comprises calcareous and clastic infill deposited during flooding of several basins, including the Bristol and Blythe subbasins of Lake Bouse. An intercalated ash bed, which is key to constraining its depositional age, is exposed in two locations, Buzzards Peak and Amboy. Comparative zircon tephrochronology by secondary ion microprobe analysis of U-Pb zircon crystallization ages, U-Th trace element abundances, and oxygen isotopic composition confirm a correlation between the Bouse Formation tephra and the 4.834 ± 0.011 Ma Lawlor Tuff (^(40)Ar/^(39)Ar eruption age). Zircon in a coeval tephra associated with the Heise volcanic complex in the Snake River Plain has distinctly lower (by ∼4.8‰, δ^(18)O VSMOW [Vienna standard mean ocean water]) oxygen isotopic compositions than zircon from Bouse tephra, and can be ruled out as a source. The ca. 4.834 Ma depositional age for the Bouse Formation tephra in fine-grained sedimentary beds of the flooded Bristol and Blythe subbasins requires widespread Colorado River inundation in the lower Bouse basins at that time.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1130/GES00904.1 DOIArticle
http://geosphere.gsapubs.org/content/10/2/221PublisherArticle
http://geosphere.geoscienceworld.org/content/10/2/221PublisherArticle
http://geosphere.geoscienceworld.org/content/10/2/221/suppl/DC1PublisherSupplemental File
Additional Information:© 2014 Geological Society of America. Received 21 January 2013; Revision received 29 December 2013; Accepted 5 February 2014; Published online 17 March 2014. This research was supported by the Gordon and Betty Moore Foundation. This is Caltech Tectonic Observatory Contribution 220. Funding for field work and age dating in the southern Bristol Mountains came from the U.S. Geological Survey EDMAP Program and a Geological Society of America Structural and Tectonics Division 2010 Student Research Grant. The ion microprobe facility at University of California, Los Angeles (UCLA), is partly supported by a grant from the Instrumentation and Facilities Program, Division of Earth Sciences, National Science Foundation. The Buzzards Peak ash sample was helpfully provided by John Spencer; multiple archived proximal Lawlor Tuff and Neroly Formation samples were provided by Andrei Sarna-Wojcicki, Dave Miller, and Al Deino, although ultimately the only Lawlor Tuff sample with sufficient zircon for statistical analysis came from a new collecting trip to the original sample collecting sites under the guidance of Sarna-Wojcicki. Miller initially mapped the basement and volcanic rocks in the south Bristol Mountains and showed me the isolated outcrop of the Bouse Formation north of Amboy. Joann Stock provided tremendous support as a graduate advisor. Ilya Bindeman, Axel Schmitt, and Kathryn Watts helpfully facilitated reanalysis of the Heise volcanic zircons. I thank Oscar Lovera (UCLA) for providing the software for the statistical analysis of zircon results. Kathryn Watts, Jorge Vazquez, and Kyle House provided helpful reviews.
Group:Caltech Tectonics Observatory
Funders:
Funding AgencyGrant Number
Gordon and Betty Moore FoundationUNSPECIFIED
USGS EDMAP ProgramUNSPECIFIED
Geological Society of America Structural and Tectonics Division 2010 Student Research GrantUNSPECIFIED
NSF Division of Earth Sciences Instrumentation and Facilities Program UNSPECIFIED
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Caltech Tectonics Observatory220
Record Number:CaltechAUTHORS:20140807-091535811
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20140807-091535811
Official Citation:Janet C. Harvey Zircon age and oxygen isotopic correlations between Bouse Formation tephra and the Lawlor Tuff Geosphere, April 2014, v. 10, p. 221-232, First published on March 17, 2014, doi:10.1130/GES00904.1
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:48169
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:07 Aug 2014 16:29
Last Modified:07 Aug 2014 16:29

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