Patterns of magma flow in segmented silicic dikes at Summer Coon volcano, Colorado: AMS and thin section analysis

Earth and Planetary Science Letters
By: , and 

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Abstract

A complex pattern of magma flow is found in two silicic dikes of a radial swarm at Summer Coon, an eroded stratovolcano in southern Colorado. The two intrusions are broken into multiple segments that suggest vertical dike propagation. However, anisotropy of magnetic susceptibility (AMS) measurements and thin section observations suggest that magma flow was often subhorizontal and away from the center of the volcano. Segments that are proximal to the central intrusion are characterized by magma that flowed steeply upward at the proximal segment extremity, then laterally along the segment, and finally downward at the distal end of the segment. Magma flow in offset segment tips located far from the volcano center was subhorizontal towards the adjacent segment, implying lateral propagation of segment tips towards one another. This observation suggests relatively high driving pressure in distal dike segments, as supported by dike thickening with radial distance from the center of the volcano. The present study indicates that radial dike evolution at stratovolcanoes is dominated by lateral flow of magma and dike segmentation is a poor magma flow indicator. A horizontally propagating radial dike has the potential to cause an eruption low on the flank of a composite cone, which poses a significant yet largely unrecognized hazard to population centers and infrastructure that may surround the volcano.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Patterns of magma flow in segmented silicic dikes at Summer Coon volcano, Colorado: AMS and thin section analysis
Series title Earth and Planetary Science Letters
DOI 10.1016/S0012-821X(03)00706-4
Volume 219
Issue 1-2
Year Published 2004
Language English
Publisher Elsevier
Contributing office(s) Hawaiian Volcano Observatory
Description 15 p.
First page 155
Last page 169
Country United States
State Colorado
Other Geospatial Summer Coon volcano