When ignimbrite meets water: Megascale gas-escape structures formed during welding

Peter W. Lipman

doi:10.1130/g45772.1

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When ignimbrite meets water: Megascale gas-escape structures formed during welding

Peter W. Lipman

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Abstract

Diverse welding, crystallization, and structural features develop when a hot ignimbrite encounters external water, depending largely on volatile-rock ratios. Such processes are spectacularly documented by a regional ignimbrite, where ponded within an older caldera in the San Juan Mountains, Colorado. Interaction of hot pyroclastic flows with moist underlying sediments or standing water in a stream valley or shallow-lakeshore environment produced mega-scale gas-escape structures, quenched adjacent tuff, inhibited welding, and generated nonplanar crystallization zones. This site provides a context for reviewing examples of ignimbrite-water interaction elsewhere.

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Geology Article

Source-reported bounding extent: 36.94989178681327° to 38.30718056188316° latitude; -109.072265625° to -104.853515625° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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Peter W. Lipman. 2018-12-07. When ignimbrite meets water: Megascale gas-escape structures formed during welding. https://doi.org/10.1130/g45772.1

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