deck

geodynamics of flat slabs

South American flat slabs appear in vicinity of cold and thick cratons, correlate spatially with buoyant oceanic impactors, as is the case of Peru and central Chile, and require slab rollback
buoyant oceanic ridges alone do not result in strong slab flattening
in central Mexico the continental lithosphere is very thin or even missing, and the oceanic Cocos plate lacks large buoyant features...the ultimate cause of slab flattening is yet to be found

Weak wedge or strong wedge?

P_{arc} = \frac{2\eta v_s \sin(\alpha)}{r(\pi - \alpha) + \sin(\alpha)}

P_{arc} = \frac{2\eta v_s \sin(\alpha)}{r(\pi - \alpha) + \sin(\alpha)}

McKenzie, 1969, Tovish, 1978

Weak wedge or strong wedge? can be both
Temp-dependent visc. must be buffered
Decoupling depth is critical
Role of slab 'anchoring' in lower mantle
Steps in upper plate thickness important as they further increase pressure anomaly