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Title: Distinguishing and Correlating Deposits from Large Ignimbrite Eruptions Using Paleomagnetism: the Cougar Point Tuffs (Mid-Miocene), Southern Snake River Plain, Idaho, USA
Authors: Finn, David R.
Coe, Robert S.
Brown, Ethan
Branney, Michael
Reichow, Marc K.
Knott, Thomas
Storey, Michael
Bonnichsen, Bill
First Published: 17-Sep-2016
Publisher: American Geophysical Union
Citation: Journal of Geophysical Research: Solid Earth, 2016, 121 (9), pp 6293-6314
Abstract: In this paper, we present paleomagnetic, geochemical, mineralogical, and geochronologic evidence for correlation of the mid-Miocene Cougar Point Tuff (CPT) in southwest Snake River Plain (SRP) of Idaho. The new stratigraphy presented here significantly reduces the frequency and increases the scale of known SRP ignimbrite eruptions. The CPT section exposed at the Black Rock Escarpment along the Bruneau River has been correlated eastward to the Brown's Bench escarpment (six common eruption units) and Cassia Mountains (three common eruption units) regions of southern Idaho. The CPT records an unusual pattern of geomagnetic field directions that provides the basis for robust stratigraphic correlations. Paleomagnetic characterization of eruption units based on geomagnetic field variation has a resolution on the order of a few centuries, providing a strong test of whether two deposits could have been emplaced from the same eruption or from temporally separate events. To obtain reliable paleomagnetic directions, the anisotropy of anhysteretic remanence was measured to correct for magnetic anisotropy, and an efficient new method was used to remove gyroremanence acquired during alternating field demagnetization.
DOI Link: 10.1002/2016JB012984
ISSN: 2169-9356
eISSN: 2169-9313
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: Copyright © 2016, American Geophysical Union. All rights reserved.
Appears in Collections:Published Articles, Dept. of Geology

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