My research has focussed on the Woodlark Rift in southeastern Papua New Guinea. This is one of the youngest and most rapidly extending continental rifts in the world, and is an intriguing locality for investigating how continents break apart. Within the most highly-extended continent lie the D’Entrecasteaux Islands (DIs), comprising metamorphic core complexes that contain the world’s youngest ultra-high pressure coesite eclogite, which appears to have been exhumed at rates of ~20 mm/yr. I have applied a variety of seismological techniques to investigate this region, using data from a temporary array that ran from 2010-2011, and was installed by members of the LDEO seismology dept..
My analysis of shear-wave splitting, using mantle-traversing teleseisms, shows strong anisotropy beneath the DIs, which I have attributed to crystallographic fabric in the shallow mantle caused by the rate and extent of continental rifting. I have related anisotropy and shear strain in the shallow convecting mantle to predict shear-wave splitting times that are very close to the splitting times I observe, bolstering our hypothesis that the anisotropy arises from mantle fabric, in turn related to rifting. My findings constrain the way in which mantle flow transitions as a rift matures from a small-scale extensional regime to a large-scale divergent boundary.
At present, I am conducting body-wave tomography in the same region, using teleseismic P- and S- wave arrivals. I hope to make use of our understanding of pervasive mantle fabric to measure anisotropic seismic velocity heterogeneities. This project should yield a detailed understanding of the kinematics and history of this rift, and the relationship between the DIs and the more developed rift to their east.