TAYLOR-MILL ANALOGS FOR PATTERNS OF FLOW AND DEFORMATION IN ROCKS

The Giesekus design of Taylor's four-roll mill has been restored and i s here used in novel flow visualizations of both pulsating and monoton ously increasing strains. The particle movement paths and progressive deformation patterns visualized in these physical experiments are in a greement with those previously calculated analytically and constructed graphically. The progressive deformation of passive material markers is guided by flowlines. Circular flowlines accommodate rigid-body rota tions without deformation. Elliptical flowlines result in pulsating st rains. The maximum strain occurs when material particles, which were i nitially at the short axis of the elliptical flowlines, reach the long axis of the flow patterns. Monotonically increasing strains occur whe n flowlines are hyperbolic. The insight thus gained is extrapolated to suggest practical methods and assumptions that allow the reconstructi on of particle movement paths from deformation features commonly obser ved in rocks. (C) 1998 Published by Elsevier Science Ltd.