Revisions to the age of the Brunhes ‐ Matuyama Boundary and the Pleistocene geomagnetic polarity timescale
- 19 June 1992
- journal article
- Published by American Geophysical Union (AGU) in Geophysical Research Letters
- Vol. 19 (12) , 1181-1184
- https://doi.org/10.1029/92gl01125
Abstract
The currently referenced age of 730 ka for the Brunhes‐Matuyama (B‐M) geomagnetic polarity boundary [Mankinen and Dalrymple, 1979] is based largely on K‐Ar and paleomagnetic data from postcollapse rhyolites in the Valles Caldera, New Mexico [Doell and Dalrymple, 1966; Doell et al., 1968]. Dating of sanidine from Valles rhyolites by the 40A/39Ar laser fusion technique indicates that samples critical to defining the B‐M boundary are up to 90 ka older than previously thought. The new data combined with earlier results yield an age for the B‐M boundary of 780 ± 10 ka. 40Ar/39Ar ages from other samples suggest the Jaramillo normal polarity subchron extended from 1010 to 915 ka.This publication has 17 references indexed in Scilit:
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