Crystallographic preferred orientation development by dissolution-precipitation creep

Crystallographic preferred orientations (CPOs) in deformed rocks are common ly interpreted as resulting from crystal plastic deformation mechanisms, wh ere deformation is achieved by the movement of dislocations. In this paper we investigate the possibility of CPO-development by dissolution-precipitat ion creep or pressure solution. A numerical model is presented, which simul ates the development of a grain aggregate that deforms by reaction-controll ed dissolution-precipitation creep. Grains are simulated as rectangular bar es that change their shape by growth, or dissolution of their surfaces, dep ending on the normal stresses acting on the individual surfaces. Grains can also rotate due to an applied vorticity (for non-coaxial deformation) and if they have a non-equidimensional shape. For each strain increment, stress that is applied to the grains is the same for all grains, while individual grains deform and rotate by different amounts. A variety of CPOs develop a t moderate strains, depending on the reaction rates of the different crysta l-surfaces and type of deformation (uni-axial shortening, plane strain pure shear and simple shear). The modelling results confirm that dissolution-pr ecipitation creep may play a role in CPO-development in rocks. (C) 2000 Els evier Science Ltd. All rights reserved.