What is the pattern of recent tectonic activity among locations of recent/on-going exhumation of ultra high pressure (UHP) rocks in eastern Papua New Guinea?
Through stream profile analysis, geomorphic mapping, landscape evolution modeling, and low temperature (U-Th)/He thermochronometry of apatite and zircon, my current research aims to complement previous structural geologic mapping and higher temperature thermochronometry done in the D’Entrecasteaux Islands, off of the eastern tip of Papua New Guinea. stern tip of Papua New Guinea. The world’s youngest UHP rocks (8-2 Ma) crop out on these islands yet the mode of their exhumation is debated. Competing models attribute exhumatio
n to (a) lithospheric simple shear in which metamorphic core complexes are formed by detachments reactivating a subduction megathrust or (b) lithospheric pure shear in which vertical extrusion of subducted, buoyant, overthickened continental crust through the megathrust and upper plate. My goal is to test the two models above using geomorphic and thermochronometric evidence.
Perspective view of Fergusson Island, showing faceted spurs and north dipping detachment fault of young metamorphic core complex. (View to the southeast.)