Deformation mechanisms operating in naturally deformed halite rocks as deduced from microstructural investigations

Abstract

In this paper we describe the microstructures of naturally deformed rocksalt samples from the Asse salt anticline, FRG, as revealed by a chemical polishing-etching procedure, and by gamma-irradiation. Evidence is presented for the operation of dislocation creep processes, accompanied by extensive strain-induced grain boundary migration. Grain boundaries can be shown to have contained thin brine films during recrystallization, suggesting that solution-precipitation processes could also have been important deformation mechanisms. Recrystallization and solution transfer processes have not been reported in most experimental work to date, thus casting doubt on the validity of extrapolating these data to predict the long-term creep behaviour of salt during natural flow.