The Relationship of Textures and Depositional Structures in Pyroclastic-flow Deposits to Paleomagnetically Determined Emplacement Temperatures

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9316538 Smith Remarkably little is known about the temperature at which pyroclastic particles are transported. Many factors, other than the initial magma temperature, are known to affect the emplacement temperature of pyroclastic flows. these factors are known, or hypothesized, to be related to descriptive and quantifiable textural and structural characteristics of pyroclastic-flow deposits (ignimbrites), including vesicularity, grain-size distribution, grain morphology, bedding structures, and grading profiles. In this study, these characteristics will be compared to emplacement temperatures estimated by application of established rock-magnetism methods to previously well- studied ignimbrites. The same approach will also be utilized to investigate a pyroclastic-flow deposit that was the product of a subaerial eruption but can be traced from the subaerial setting to a subaqueous depositional environment. Establishment of the thermal and textural changes of the deposit that occur in the transition will be critical to ongoing controversy on the nature of such transitions, which are critical to understanding pyroclastic- flow transport.