Miocene welded tuff near Shoshone, Nevada

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Miocene welded tuff near Shoshone, Nevada
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Fiamme
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Summary of THEMIS layer characteristics

• Layer is more competent than surrounding MFF
  Amm3 materials
• (2 to 4 K cooler than surroundings at 15.43 H
  local time)
• Materials above the competent layer are more
  easily eroded,
• leading to formation of an erosional bench at
  the layer level
• MOC images in the area show multiple dark layers
  within
• MFF materials, tens of meters thick (which
  would not be fully
• resolved by 100 m THEMIS IR pixels, but still
  detectable)
• All of these characteristics are consistent with
  erosion and
• exposure of welded zone(s) within non-welded
  tuff
• It is more difficult to reconcile all of the
  above observations
• to the other proposed hypotheses of origin

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Summary

• THEMIS daytime IR data reveal a competent, more
  resistant
• layer within a scarp in the Amm3 unit of MFF
• The physical attributes of this layer are most
  consistent
• with the hypothesized ignimbrite origin for MFF

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