Publication Citation

USGS Series Professional Paper
Report Number 1602
Title Geology, age, and tectonic setting of the Cretaceous Sliderock Mountain Volcano, Montana
Edition -
Language ENGLISH
Author(s) Du Bray, E. A.; Harlan, Stephen S.
Year 1998
Originating office
USGS Library Call Number (200) B no.1602
Physical description 19 p.
ISBN

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Abstract

The Sliderock Mountain stratovolcano, part of the Upper Cretaceous continental magmatic arc in southwestern Montana, consists of volcaniclastic strata and basaltic andesite lava flows. An intrusive complex represents the volcano's solidified magma chamber. Compositional diversity within components of the volcano appears to reflect evolution via about 50 percent fractional crystallization involving clinopyroxene and plagioclase. 40Ar/39Ar indicate that the volcano was active about 78?1 Ma.