Evaluation of thermal decomposition of calcite in the fault zone, a case study of the Astana fault

نویسندگان

1 Department of geology, Faculty of science, Ferdowsi University of Mashhad, Iran

2 Department of geology, Faculty of science, Ferdowsi University of Mashhad, Iran

doi
10.22059/geope.2023.330741.648634
چکیده

AbstractAstaneh fault is one of the active and seismic faults in the southern part of eastern Alborz. Performance of seismic faults in carbonate rocks and favorable conditions causes the change in calcite and its conversion to lime or its thermal decomposition. If the environment is suitable for this deformation, after initial deformation, the primal volume is reduced, leaving the space available for depletion between deformed particles, which can be used as a key for this earthquake slip. During the Astaneh fault at the location where the fault occurred in the carbonates, after sampling the fault core and fault gouge, and photographing and studying them by SEM electron microscopy, the presence of Co2 exit bubbles and the reduction of calcite volume caused by the earthquake slip heat created was observed at the nanoscale and micro level. After observing the thermal decomposition of calcite in the gouge fault, the reduced volume of particles was calculated from the earthquake slip heat. With the proportion between this volume reduction and the temperature causing it the temperature resulting from the seismic slip causing this deformation is estimated for the sampling location and fault surface.Keywords: Astaneh fault, Earthquake slip, thermal decomposition of calcite, Fault gouge, volume reduction