Comparison of the TRM of the Yellowstone Group and the DRM of some Pearlette ash beds

Journal of Geophysical Research B: Solid Earth



Air fall ash beds (Pearlette) originating from rhyolitic eruptions in the Yellowstone‐Island Park region of Wyoming and Idaho are discontinuous but widespread throughout the western United States. Accumulation and deposition of ashes occurred in low‐energy fluvial and lacustrine environments. These ash beds have been correlated, according to their chemistry and remanent magnetism, with specific eruptions of tuffs of the Pleistocene Yellowstone Group. Type O Pearlette ash beds are normally magnetized and correlate with the Lava Creek Tuff (0.60 m.y.), whereas type S Pearlette ash beds are reversely magnetized and correlate with the Mesa Falls Tuff (1.22 m.y.). The mean direction of detrital remanent magnetization (DRM) of 11 type O Pearlette ash beds is identical to the mean direction of thermal remanent magnetization (TRM) of the Lava Creek Tuff after correcting for differences in site latitude and longitude. Considered separately, only 2 of the 13 Pearlette ash beds studied possess mean inclinations significantly shallower than, and only 4 have mean declinations significantly different from, those of their correlative tuffs. Identical directions of magnetization measured from evenly laminated and highly contorted type O ash suggest that a readjustment of magnetic grains in water‐saturated ash shortly after deposition may account for the close agreement of TRM and DRM.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Comparison of the TRM of the Yellowstone Group and the DRM of some Pearlette ash beds
Series title Journal of Geophysical Research B: Solid Earth
DOI 10.1029/JB084iB09p04525
Volume 84
Issue B9
Year Published 1979
Language English
Publisher American Geophysical Union
Contributing office(s) Geosciences and Environmental Change Science Center
Description 8 p.
First page 4525
Last page 4532
Country United States
State Idaho, Montana, Wyoming
Other Geospatial Yellowstone Group
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