diddly-squat said:
diddly-squat said:
Michael V said:
http://en.wikipedia.org/wiki/Pseudotachylite
http://geology.about.com/od/rocks/a/aa_fractfrict.htm
The second one has some links to explanations about other fault-rocks.
These are minerals associated with fluid transfer around fault zones. They are not created by ‘pressures released in earthquakes’ (what ever that is supposed to mean).
Ok.. Just read the wiki page… Seem it’s believed they are the result of hearing due to friction between fault surfaces created during seismic events..
“Now there is strong evidence that large subduction faults, like the one that caused the 2004 Sumatra earthquake, can melt pseudotachylites. Researcher Christen Rowe has documented clear examples from Kodiak Island, where ancient strands of the Alaskan subduction zone are exposed. The melted zones there are more than 10 centimeters thick.”
This from the second article was pretty well what I was looking for.