Effect of water on the rheology of experimentally deformed quartzite

Empirical flow laws have been determined for Simpson quartzite samples deformed to mechanical steady state in the α-quartz stability field using Griggs-Blacic solid-medium deformation apparatus. Experiments were conducted on samples both as received ("dry') and with water added via the dehydration of a talc confining medium ("wet'). Best fits of the power law type yield a stress exponent of 2.72 ± 0.19, an activation enthalpy of 134 ± 32 kJ mol^-1, and a preexponential constant of 1.16 [+1.15, -0.58] × 10^-7 MPa^-2.72s^-1 for the dry quartzite law; and are 2.61 ± 0.15, 145 ± 17 kJ mol^-1, and 5.05 [±5.00] × 10^-6 MPa^-2.61s^-1 for the wet quartzite. The enhanced hydrolytic weakening of the wet experiments appears to affect the flow laws mostly in the preexponential constants, possibly as a defect concentration term that is higher in the wet than in the dry law. Recrystallization is well developed in the wet but not the dry specimens. -from Authors