Paleomagnetism, potassium-argon ages, and geology of rhyolites and associated rocks of the Valles Caldera, New Mexico

Richard R. Doell; G. Brent Dalrymple; Robert L. Smith; Roy A. Bailey

doi:10.1130/mem116-p211

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Paleomagnetism, potassium-argon ages, and geology of rhyolites and associated rocks of the Valles Caldera, New Mexico

Richard R. Doell·G. Brent Dalrymple·Robert L. Smith·Roy A. Bailey

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Abstract

Paleomagnetic and potassium-argon studies support geologic evidence that the lower member of the Bandelier Tuff was deposited 1.4 m.y. ago. The upper member erupted about 1.0 m.y. ago and was followed by caldera collapse which formed the 12- to 14-mile diameter Valles Caldera. Postcaldera activity which resulted in the eruption of rhyolite domes and pyroclastic material, has occurred at about 0.9, 0.7, 0.5, and 0.4 m.y. ago, with later undated eruptions that were estimated at about 0.1 m.y. ago. These data from the Valles Caldera are the basis for the previously published age revision of the Brunhes-Matuyama geomagnetic polarity epoch boundary from 1.0 to 0.7 m.y. ago, and they were used to define the Jaramillo normal polarity event at about 0.9 m.y. ago (Doell and Dalrymple, 1966).

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Source-reported bounding extent: 35.61711648382185° to 36.10015727402227° latitude; -107.04803466796875° to -106.1883544921875° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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Richard R. Doell, G. Brent Dalrymple, Robert L. Smith, Roy A. Bailey. 1968-01-01. Paleomagnetism, potassium-argon ages, and geology of rhyolites and associated rocks of the Valles Caldera, New Mexico. https://doi.org/10.1130/mem116-p211

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