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Full-Text Articles in Volcanology
Igneous Dikes At Long Valley, Ca: Emplacement Mechanisms And Associated Geologic Structures, David D. Pollard, Jonathan H. Fink, Paul T. Delaney
Igneous Dikes At Long Valley, Ca: Emplacement Mechanisms And Associated Geologic Structures, David D. Pollard, Jonathan H. Fink, Paul T. Delaney
Geology Faculty Publications and Presentations
Two hypotheses for dike emplacement are: (1) magma flows into and dilates pre-existing fractures; or (2) magma flows into and dilates self-generated fractures. In the first case dikes should be parallel to an element of the rock fabric; in the second, they should be perpendicular to the least compressive stress. The two hypotheses suggest different dike intrusion and fissure eruption mechanisms and therefore different strategies for monitoring igneous events at Long Valley. We derive a method to distinguish the two mechanisms, a priori, from in-situ stress measurements and estimates of magma pressure. Estimates of relative dilation and slip across a …