Incorporation and redistribution of locally derived lithic fragments within a pyroclastic flow

Geological Society of America Bulletin
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Abstract

The lower Miocene Peach Springs Tuff exposed in the Newberry Mountains, California, was deposited within a paleovalley trending S65??W. A model is proposed whereby a turbulent boundary layer at the base of the pyroclastic flow is induced by surface roughness of the substrate and incorporates loose material from the substrate to produce a high-density ground layer that decouples from the lower-density, ash-rich pyroclastic flow. After decoupling has occurred, the high-density, lithic-rich ground layer moves independently from the ash-rich pyroclastic flow. The lithic breccia horizons have many characteristics of proximal (lag) breccias, and caution must be used when inferring distance from vent in ancient ignimbrites based on the occurrence of coarse breccias. -from Author

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Incorporation and redistribution of locally derived lithic fragments within a pyroclastic flow
Series title Geological Society of America Bulletin
DOI 10.1130/0016-7606(1992)104%3C1193:IAROLD%3E2.3.CO;2
Volume 104
Issue 9
Year Published 1992
Language English
Publisher GSA
Contributing office(s) Geology, Minerals, Energy, and Geophysics Science Center
Description 15 p.
First page 1193
Last page 1207