D.E. Champion R.L. Christiansen G. A. Izett J. D. Obradovich M. A. Lanphere 2002 <p>⁴⁰Ar/³⁹Ar ages were determined on the three major ash-flow tuffs of the Yellowstone Plateau volcanic field in the region of Yellowstone National Park in order to improve the precision of previously determined ages. Total-fusion and incremental- heating ages of sanidine yielded the following mean ages: Huckleberry Ridge Tuff—2.059 ± 0.004 Ma; Mesa Falls Tuff— 1.285 ± 0.004 Ma; and Lava Creek Tuff— 0.639 ± 0.002 Ma. The Huckleberry Ridge Tuff has a transitional magnetic direction and has previously been related to the Reunion Normal- Polarity Subchron. Dating of the Reunion event has been reviewed and its ages have been normalized to a common value for mineral standards. The age of the Huckleberry Ridge Tuff is significantly younger than lava flows of the Reunion event on Ré union Island, supporting other evidence for a normal-polarity event younger than the Reunion event.</p> application/pdf 10.1130/0016-7606(2002)114<0559:RAFTOT>2.0.CO;2 en GeoScienceWorld Revised ages for tuffs of the Yellowstone Plateau volcanic field: Assignment of the Huckleberry Ridge Tuff to a new geomagnetic polarity event article