2020 Hochstetter Lecture, Masterton
2020 Hochstetter Lecture: “The interplay of mechanical properties and stress in controlling the tectonic and topographic evolution of dynamic landscapes”
The landscape serves as a link between the solid Earth and the atmosphere. At many spatial and temporal scales, landscape morphology and topography provide a constraint on the tectonics of the deeper Earth and the processes active within it. To unravel these, we need to understand the complex relationships between surface processes, their drivers and the rocks upon which they act. I will explore recent developments in modelling tectonics and surface processes within a single deformational framework. I will focus on collisional settings such as New Zealand’s Southern Alps, SE Alaska and the Himalaya where rapid uplift combines with vigorous climate regimes to create dynamic landscapes.
3D mechanical models, constrained by field observations, are solved for the complete stress tensor, including both geodynamic and geomorphic components (tectonic, dynamic, topography, fluvial, glacial). They also predict where imposed tectonic driving forces result in deformation-induced weakening of the rock mass in the form of faults and other structures. The balance between the rock strength and 3D stresses acting upon the rock mass determines whether or not rock at the surface breaks, which makes it potentially available to be acted upon by surface processes.