Rheological properties of paraffin as an analogue material for viscous crustal deformation

The rheological stratification induced by temperature variations within the crust requires analogue materials with temperature-sensitive viscosity to properly simulate the change of mechanical properties with depth. Rheologic al calibration experiments on commercial paraffin wax with melting point of 53 +/- 1 degrees C show that this material is a nonlinear fluid (1.6 less than or equal to n less than or equal to 12.1) for homologous temperatures T/T-m < 0.70, and an approximately Newtonian fluid (1.0 less than or equal to n less than or equal to 1.3) for T/T-m greater than or equal to 0.70. Th e decrease in the stress exponent it is probably associated with the alpha- beta phase transition of paraffin. Effective viscosity values are strongly temperature dependent, varying by nine orders of magnitude from 10(10) to 1 0 Pa s in the temperature range between 30 and 52 degrees C. The rheologica l properties of paraffin make this material useful for modelling crustal rh eology and tectonic processes, when linear dimensions and time scale down b y a factor of 10(6) and 10(11), respectively. (C) 1999 Elsevier Science Ltd . All rights reserved.