[J05-3] Crustal dynamics: Multidisciplinary approach to seismogenesis III

[J05-3-05] A new temperature proxy on faults during earthquake by using maturity of carbonaceous materials: Kinetic effect on the maturation

^○Shunya Kaneki, Tetsuro Hirono (The University of Osaka, Osaka, Japan)

Quantitative estimation of frictional heat produced in the fault zone (i.e., maximum temperature) is one of the keys to estimate the slip behaviors of earthquakes. Irreversible thermal maturation reaction of carbonaceous materials, which is very sensitive to maximum temperature, is reported to be a great indicator for frictional heat recorded in fault rocks. In fact, such maturation process could be strongly affected not only by maximum temperature but also by heating rate. However, previous studies have conducted under the heating rate of ~1 degree per second, which is markedly lower than that during earthquake slip (several tens to several hundreds of degrees per second). Here we performed new heating experiments at two different heating rates (~1 and ~100 degrees per second) by using carbonaceous material sampless retrieved from an ancient plate-subduction fault. We then carried out IR and Raman spectroscopic analyses and py-GC/MS analysis to characterize the degree of the maturation. The samples after high heating rate of 100 degrees per second showed relatively low maturation than those after 1 degree per second-heated samples. Thus, heating rate is one of the important factors to estimate the maximum temperature recorded in the faults, and our results could indicate that previous researches underestimate the temperature.