Lithosphere Rheology: An Assessments Based on a Combination of Experimental and Microstructural Analyses. (Invited)

A combination of experimental and microstructural analyses provides a strong constraint on the rheological properties of the lithosphere and the origin of the lithosphere-asthenosphere boundary. The remarkable similarity between the evolution of LPO with increasing strain in experimental and natural samples under both wet and dry conditions provides a strong basis for the application of laboratory flow laws in geodynamic models. These comparisons also support the interpretation that major rheological boundaries may arise owing to variations in water content - in contrast to recently reported hypotheses based solely on diffusion kinetics in olivine. In this presentation I will summarize pertinent results that support these conclusions and assess how our understanding of the processes that influence effective viscosity can be applied to evaluate the origin of the lithosphere-asthenosphere boundary, the conditions where convective instabilities mare arise at the base of the lithosphere and the contrast in strength/rheology of plates and plate boundaries.