15 September, 2009 (16:00 GMT), 5 Merrion Square, Dublin 2.

Speaker: Dr. Indrajit G. Roy, Onshore Energy and Minerals Division, Geoscience Australia.
Title: Joint and cooperative inversion of seismic travel time, magnetotelluric and bouguer gravity data to define the architecture of the Millungera Basin, North Queensland, Australia.

Lecture Notes: Link

Abstract:

North Queensland, Australia, has world-class mineral deposits, including high-grade zinclead-silver and copper, significant iron-oxide copper-gold and medium sized uranium deposits. The region also has potential for previously unrecognised mineral and energy systems, such as sandstone-hosted uranium deposits, geothermal energy and petroleum. Recently, researchers at Geoscience Australia have discovered a previously unknown Millungera Basin; however knowledge of its evolution and the architecture is limited. As part of the Australian Government’s Onshore Energy Security Program and the Queensland Government’s Smart Mining and Smart Exploration Initiatives three deep seismic reflection and broad-band magnetotelluric surveys were conducted in 2007 in North Queensland to establish the architecture and geodynamical framework of the area. One of the seismic and magnetotelluric transects were carried out across Millungera Basin. Bouguer gravity and high-resolution airborne magnetic data are also available in the area. These data provide a unique opportunity to integrate various geophysical methods in the modelling, in addition to model each geophysical data as in a stand-alone mode in order to define the architecture of the Millungera Basin. Such an approach is important to build a cohesive interpretation, as geophysical methods with disparate data sets address variations of different rock physical properties. The initial phase of interpretation involves identifying the trace of geological features on both horizontal and vertical planes via both qualitative interpretation from the images of potential field and time-migrated stacked seismic data and quantitative interpretation via 3D inversions of the gravity and magnetic data and 2D inversions of the broad-band magnetotelluric data separately. A novel strategy of quantitative interpretation using the various geophysical methods synchronously has been developed where seismic travel time, magnetotelluric and Bouguer gravity data are integrated via both joint and cooperative inversions. The technique is applied to interpret the Millungera Basin of North Queensland.