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U-Pb zircon geochronology of calc-alkaline ash-flow tuff units in the Mogollon-Datil volcanic field, southern New Mexico

By
Shannon P. Rentz
Shannon P. Rentz
Department of Geography, Geology & Planning, Missouri State University, 901 S. National Avenue, Springfield, Missouri 65897, USA
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Gary S. Michelfelder
Gary S. Michelfelder
Department of Geography, Geology & Planning, Missouri State University, 901 S. National Avenue, Springfield, Missouri 65897, USA
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Matthew A. Coble
Matthew A. Coble
Stanford–U.S. Geological Survey Micro-Analytical Center, Department of Geological Sciences, Stanford University, 367 Panama Street, Stanford, California 94305, USA
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Emily Salings
Emily Salings
Department of Geography, Geology & Planning, Missouri State University, 901 S. National Avenue, Springfield, Missouri 65897, USA
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Publication history
20 March 201819 September 2018

ABSTRACT

The Mogollon-Datil volcanic field is a 40–24 Ma cluster of calderas that formed during ignimbrite flare-up eruptions in southern New Mexico associated with subduction, and possible delamination, of the Farallon plate beneath the North American plate. This study uses magmatic zircon sampled from four ignimbrites from a nested caldera system and an additional ignimbrite located outside of the nested system to compare the processes and timing of magma accumulation in southern New Mexico. These ignimbrites include: the Whitewater Tuff, the Cooney Canyon Tuff, the Davis Canyon Tuff, and the Shelley Peak Tuff from the Mogollon Mountains and the Bell Top 4 Tuff from the Uvas volcanic field. The ignimbrites range from crystal-poor, high-silica rhyolite to crystal-rich, low-silica rhyolite. We compare previous 40Ar/39Ar sanidine eruption ages to new U-Pb crystallization ages and trace-element compositions of zircon. Weighted mean zircon ages define two magmatic groups. Group one includes the Bell Top Tuff (34.5 ± 0.5 Ma), the Cooney Canyon Tuff (34.8 ± 0.8 Ma), and the Whitewater Creek Tuff (36.2 ± 0.4 Ma). The second group includes the Davis Canyon Tuff (28.7 ± 0.5 Ma) and the Shelley Peak Tuff (29.6 ± 0.5 Ma). Weighted mean zircon ages are within published 40Ar/39Ar ages, with the exception of the Shelley Peak Tuff, which is ~1 m.y. older. Hafnium contents and Th/U and Yb/Gd ratios suggest the dominant mechanism that produced eruptible melt was rejuvenation or remobilization of a crystal mush accompanied by minimal partial melting of the continental crust.

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GSA Special Papers

Field Volcanology: A Tribute to the Distinguished Career of Don Swanson

Geological Society of America
Volume
538
ISBN electronic:
9780813795386

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