The use of magnetic susceptibility and its frequency dependence for delineation of a magnetic stratigraphy in ash-flow tuffs

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Variations in the grain size, amount, and mineralogy of magnetic phases in layered volcanic rocks define a magnetic stratigraphy that can be identified by means of magnetic susceptibility measurements. In ash-flow tuffs, grain size and other variables that control susceptibility are to a large extent a function of the cooling and alteration history. At Yucca Mountain, Nevada, laterally-continuous high-susceptibility (~ 10-2 SI) horizons exist in the Paintbrush Tuff due to the presence of either precipitates or phenocrystic Fe-Ti oxides. The frequency dependence of magnetic susceptibility, χ(ω), can be used to discriminate between horizons with superparamagnetic precipitates and horizons with multi-domain phenocrystic material. Interpretation of variations established by field and laboratory susceptibility data has been constrained by petrography and transmission electron microscopy (TEM) . -from Authors

Original languageEnglish (US)
Pages (from-to)783-786
Number of pages4
JournalGeophysical Research Letters
Issue number6
StatePublished - 1990
Externally publishedYes


ASJC Scopus subject areas

  • Medicine(all)
  • Earth and Planetary Sciences (miscellaneous)

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