Lithic Fragments In The Bandelier Tuff, Jemez Mountains, New Mexico
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Journal Article: Lithic Fragments In The Bandelier Tuff, Jemez Mountains, New Mexico
AbstractLithic fragments are a highly varied but significant component of the Bandelier Tuff, Jemez Mountains, New Mexico. Lithic material occurs in concentrations from trace amounts to 30 wt.%, and within the Otowi Member of the tuff has a total volume of 10 km3. Approximately 90% of the fragments are Cenozoic volcanic rocks of the Jemez volcanic field, 10% are Paleozoic sedimentary rocks, and only trace amounts are Precambrian basement. The large volume of lithic material and predominance of shallowly derived fragments requires substantial flaring of the vent near the surface. The cooling effect of >= 10 wt.% lithic fragments was sufficient to inhibit welding of the tuff. Many of the basement fragments appear to have been derived from a contact metamorphic zone surrounding the magma chamber. This zone is characterized by shearing and recrystallization, by development of veins of actinolite, augite, and epidote, and by alteration of hornblende to F-rich biotite. Water and fluorine involved in the alteration may have come from the magma chamber.
- John C. Eichelberger and Frank G. Koch
- Published Journal
- Journal of Volcanology and Geothermal Research, 1979
- Not Provided
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John C. Eichelberger,Frank G. Koch. 1979. Lithic Fragments In The Bandelier Tuff, Jemez Mountains, New Mexico. Journal of Volcanology and Geothermal Research. (!) .