date: 2008 Apr.18 (Wed) 16:00 - 17:30
room: X206 (Sci-X Bldg) ,
speaker: Dr. Graham Heinson (The University of Adelaide, Australia)
title: Imaging the Australian crust and mantle using magnetotellurics
abstract: Australia is an excellent laboratory for studying fundamental properties of the lithosphere, with a diversity of geological processes over a four billion years history. In this seminar I will talk about the MT method and some recent onshore and offshore studies, including the Gawler Craton in South Australia, and the Northwest Shelf in Western Australia. The MT method yields a measure of Earth's electrical resistivity that varies over seven orders of magnitude, making it one of the most diagnostic physical properties of Earth. In the upper crust, fluids and some mineral phases dominate conduction, but at mid-lower crustal depths and in the upper mantle, resistivity is a related to temperature of metamorphism, mineralogy and degree of deformation. Models presented in this seminar suggest that MT data, combined with seismic and potential field data, can provide evidence for the geometry of geological structures, and the geochemical and metamorphic evolution of the crust and mantle.