Anisotropy of Magnetic Susceptibility of Welded Ignimbrites

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Anisotrophy of magnetic susceptibility (AMS) is a potentially powerful indicator of rock fabric (preferred grain orientation) that has not been fully exploited as a tool in volcanology. This proposal seeks funds for a much more detailed investigation of AMS fabrics in welded ignimbrites than has been attempted in previous studies. Very carefully selected sites will be sampled in order to evaluate the origin and nature of AMS fabrics in welded tuffs, to map out primary flow directions on the scale of tens to hundreds of meters, to assess the effect that secondary processes (welding and rheomorphism) have on these primary fabrics, and to assess the degree to which AMS can be used to constrain mechanisms of deposition from pyroclastic flows. The Bandelier Tuff, Jemez Mountains, New Mexico will be studied.