ESCI Seminar Series: Mantle Processes, Crustal Structures and Topography in Central South Island, New Zealand
ESCI Seminar Series: Mantle Processes, Crustal Structures and Topography in Central South Island, New Zealand
Date: 18 July 2013 Time: 4.00 pmSpeaker: Geophysics PhD Candidate Emily Warren-Smith, School of Geography, Environment and Earth Sciences
New Zealand's Southern Alps are underlain by a large crustal (~48km thick) and lithospheric (>150km) root, yet little surface evidence of crustal shortening exists to explain this root's formation. I will utilise geological, geomorphological and geophysical methods in this study to examine both long-term and active continental deformation in the area around Wanaka and the Southern Lakes; this region overlies the thickest portion of the root. In particular this study focuses on constraining the dimensions of this isostatic root and quantifying the surface shortening deficit and total un-roofing. Previous studies attempting to quantify un-roofing by fission track thermochronology have been hindered by low uranium levels producing artificially young cooling ages. Through reproducing apatite and zircon cooling ages and constructing balanced structural cross-sections I hope to constrain erosion profiles across Central Otago and the Southern Lakes. Active deformation is investigated through the deployment of 8 broadband seismometers (the Central Otago Seismic Array, COSA) to examine temporal and spatial patterns in seismicity across the southern portion of the Southern Alps. This network will focus on the transition from continental collision to subduction further south in Fiordland, as well as isostatic signals associated with un-roofing as quantified by thermochronology.