Possibility and limitation of high pressure and temperature experiments on flow and fracturing of rocks and recrystallization of minerals

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1.Grain boundary migration of quartz occurred between metachert and chalcedony at the expense of fine-grained quartz grains in chalcedony during annealing experiments. The migration(M)is expressed as M=1.9t^<0.29> where t is the annealing time. The driving force for the migration is the reduction of surface energy. The velocity of grain boundary migration(V)is given by the equation: V-14(P/3g)^<4.4>,where P is the driving force and g is the specific surface energy. Grain size of chalcedony (D) is expressed as D=2.1t^<0.16>.2.Grain boundary migration under the deviatric stress occurred at the boundary between metachert and chalcedony. The migrated boundary is found to be highly serrated.3.Chalcedony can be experimentally compressed up to 60% strain using a thick carbon heater.4.Metachert can be experimentally folded by the compression parallel to the foliation.