IMPROVING FLOW LAWS AND PIEZOMETERS FOR QUARTZ AND FELDSPAR AGGREGATES

We have modified the molten salt cell (MSC) in order to measure the flow stress of quartz and feldspar aggregates deforming by dislocation creep. The flow stress of Cararra marble measured in the MSC is within 5 MPa of that measured in a gas apparatus. Quartz and feldspar aggregates deformed at 900-degrees-1100-degrees-C and confining pressures of 1000-1500 MPa in copper and calcite solid confining pressure media are about twice as strong as those deformed in the MSC, whereas quartz aggregates deformed in talc and solid NaCl have about the same strength as that measured in the MSC. These results suggest that the stress exponent in the flow law is larger and the dynamically recrystalized grain size is more sensitive to stress than previously reported.