Pseudotachylyte in bedding slip fault

( updated Feb. 26,1996 )
I found new pseudotachylyte in the field again, at Jan 15,1996. This outcrop is famous and big one that western Fujinomiya city, Shizuoka pref. central Japan. In this page show some photographs taken in the field.

All view
Lower part of this outcrop is Bessyo congromalete formation (0.7Ma?) and covered by OLFM (Older Fuji Mud Flow) (0.05Ma). Dip and strike of this bedding slip fault is N50W65W
Sliken side indicate to dip slip. Thickness of psudotachylyte (black glass) is 1-3cm.
Stereo view
Angle between joint plane and bedding (fault) plane is 90 deg.
White pumice fragments are included only upper Block.
Scanner view
Black glass inject to pumice layer.

Now, I would like to show you some beautiful photograph of thin sections that taken by SCANER (Epson GT-9000 1200dpi grayscale / backlight). I think that these are pseudotachylyte , probability 99%.
C-01 / 1.57cm*0.69cm (jpeg 65k)
F-01 / 1.56cm*1.21cm (jpeg 95k)
E-01 / 1.69cm*1.30cm (jpeg 103k)

In the thin section, many interesting texture were distinguished, one is a pressure shadow like texture.
Complete cross section of pseudotachylyte. Microscopic scale faults and sliced fragment of andesite are distinguished. The right side surface of this sample is a very rough and glassy ( C-01 ).
open ( jpeg green 116k)
open (jpeg color 363k)
Pressure shadow like texture ( E-01 ).
open (jpeg 128k)
cross (jpeg 118k)

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Dept. of disaster prevention
part-time lecture of Nihon university