THERMOLUMINESCENCE AS A SCALAR MEASURE OF PLASTIC STRAIN IN EXPERIMENTALLY AND NATURALLY DEFORMED CRYSTALLINE LIMESTONES

A number of studies have indicated that the thermoluminescence (TL) sensitivity of minerals changes with deformation. A new TL peak occurs in the case of calcite. It is currently known that plastic deformation of calcite and crystalline limestones results from intracrystalline twinning and translation gliding and a correlation is established between translation gliding and the new (TL) peak. In this work, experimental deformation under a system of triaxial cylindrical stresses is performed at room temperature. It is shown that loading causing dilatancy does not give rise to the TL peak while loading that results in constant volume plastic deformation favours its development. It is shown that this TL peak grows in proportion to increasing strain and thus can be considered as a marker of the plastic deformation. This TL development is applied to the study of rocks which are naturally deformed and the results are compared to data from tectonic studies. A relationship is established between the intensity of deformation of tectonic origin and the intensity of a particular thermoluminescence peak. This enables us to use thermoluminescence to classify naturally deformed limestones according to their relative plastic deformation. © 1990.