Geophysics & Image Analysis

The Geophysics and Image Analysis theme in the CET develops new tools for exploration targeting whilst at the same time works closely with the commodity-oriented themes providing support for projects in these areas that require the relevant expertise. Current research focused in three areas;  1) Developing improved methods for processing, imaging and interpreting geological and geophysical imagery;  2) Developing mineral prospectivity tools for selected terrains in Western Australia using geophysical and other kinds of geoscientific data; and  3) Understanding the geophysical responses of mineral deposits.

Main theme researchers

Prof. Mike Dentith

Dr Eun-Jung Holden

Dr Luis Gallardo

Dr Aurore Joly

Shane Evans

Shih Ching Fu

Minh Tran

Le Yu (PhD student)

Roger Clifton (PhD student)

Research theme affiliates

Prof. Cam McCuaig, Prof. John Miller, Prof. Steve Beresford, Research Assoc. Prof. Alok Porwal, Peter Kovesi, Nick Spadacinni, Barry Bourne, Jonathan Wan, Roberto Togneri, Tele Tan

Major Projects

Automated Interpretation of Regional Geophysical and Remote Sensing Datasets (CET and Department of Earth Sciences at Zhejiang University, China)

Geophysical data sets, notably aeromagnetic data are available for vast areas around the world, often at a nominal cost. These data can be efficiently and effectively analysed (in a totally objective fashion) using image analysis methods. By identifying key geological/exploration criteria, and their associated geophysical responses, datasets can be searched for such responses. Current/recent research has concentrated on Archean lode-gold deposits, porphyry copper deposits, magnetic responses in sedimentary basins (Figs.gingin, gingin_std, gingin_stdlinephasesym) and recognising modern calderas.

Our recent research has also focused on automated interpretation of multi-channel remote sensing and geophysical datasets to create pseudogeological maps. Other lines of investigation include strategies for merging imagery and, correction for the effects of vegetation in remote sensing responses.

Automated Quantification of Olivine Crystal Size Distribution from Photographs of Polished Slabs (CET; University of British Columbia, Canada)

Manual identification of mineral species in polished slabs is extremely time consuming and subject to operator bias. An automated technique to quantify the number/amount of olivine crystals in kimberlites has been successfully developed.

Geophysical Studies of Mineralised Terrains in Western Australia (CET; GSWA)

Currently concentrating on the use of regional aeromagnetic and gravity datasets in conjunction with deep seismic and magnetotelluric data on-going and recent work has been on the Tanami, Fraser and Musgraves terrains, plus the southern Yilgarn Craton. Future studies of this type will be conjunction with the Geological Survey of Western Australia as part of the Exploration Incentives Scheme.

Through the EIS project the GSWA is seeking to improve delivery of exploration-relevant geosciences datasets to industry to attract industry investment in WA as an exploration destination and thereby maintain a pipeline of mineral deposit discoveries that will underpin the revenue base of the state government into the future. In order to achieve a step change in the exploration relevance of GSWA datasets, it has been recognized that a series of targeting products that help junior to mid-size exploration companies translate the geosciences datasets into actual ground acquisition and drill target decisions will be critical.

To this end, GSWA has approached the CET to provide these targeting products under the EIS that has recently been announced by the WA state government. Working on a terrain by terrain basis typical products of these studies include:

i).          4D Architecture based on geology-geophysics integration

a.       4D synthesis of the terrane, incorporated in detailed space time charts

b.      2D structural geology interpretation attributed according to 4D understanding of structural evolution of terrane

c.       3D volume of interpreted geology/structure

d.      Derivative datasets used to interpret above

                                          i.    Reprocessed images

                                         ii.    Inversion models

ii).          Mineral Systems analysis

a.       Commodity reviews for the terrane based on mineral systems approach and incorporated into the 4D synthesis and space-time chart

b.      Scale-dependent, mappable targeting criteria for each commodity/deposit model (camp-scale decision will be the focus).

iii).          Targeting products

a.       Empirical targeting analysis of deposit showings versus raw, derived and interpreted datasets, undertaken and delivered in Arc GIS platform

b.      2D conceptual targeting analysis using targeting model for various commodities and deposit styles (terrane dependent), undertaken and delivered in ArcGIS platform.

c.       A series of derivative datasets created in the process of doing the conceptual targeting, delivered as layers in ArcGIS

d.      Relative comparison of targeting technique outcomes and expert commentary on targeting outcomes

iv).          Presentation of products in Atlas format (full A4 images), with accompanying text to clearly communicate products to industry geoscientists.

The first terrain to be analysed is the Musgrave Complex in central Western Australia.

NEW major initiatives

Automated Interpretation of Televiewer Imagery for Mining/Geotechnical Applications Televiewer datasets, optical, acoustic, electrical, provides ‘pictures’ of the wall of a drillhole.  These datasets are large, contain a great deal of detail and take a great deal of time to manually interpret.  This project involves the development of methods for automated interpretation of such datasets, initially concentrating on the detection of fractures and analysis of fracture geometry.

Behavioural Analysis in Geoscientific Data Interpretation This study aims to profile quantitatively data interpretation behaviours of geoscientists by monitoring neurological and physical states of real-time human responses using Electroencephalography (EEG) sensors and trackers for the eye and head.  This is a collaborative research between a group of researchers at UWA and Curtin University

Joint Interpretation of Seismic Reflection, Magnetotelluric And Potential Field Data (Fig.flow chart 150) When geological structures occurs at considerable depth in the crust, only very low frequency geophysical signals can reach them and these provide images of only limited resolution. This research aims to develop a strategy to quantitatively integrate seismic reflection, magnetotelluric, gravity and magnetic data to in combination to increase the resolving power of each data set and determine the distinctive characteristics of the different geological elements at depth.

3D Inversion of Gravity, Magnetic and Seismic Data (Fig. grav-Mag-reflections) The complex three-dimensional distribution of mineral deposits makes it difficult to determine consistent and detailed models of the subsurface based on geophysical data. This research aims to develop and apply methodologies for the joint inversion of gravity, magnetic and seismic refraction data for both heterogeneous and multi-layered environments. These methodologies have been applied on large tectonic setting as well as on sedimentary basins; the applications aim to be extended to large WA terrains and localized mineralization zones.

Research Initiatives

Geophysical Studies of the Kalkarindji Flood Basalts of the Northern Territory

Optimal design of geophysical surveys based on probability analysis

Collaboration

Industry

Barrick Gold Australasia

Rio Tinto Iron Ore

Geosoft

University/Government

CSIRO ‘Minerals Down Under’

University of British Columbia

School of Computer Science and Software Engineering (UWA)

Geological Survey of Western Australia

Observatorio Nacional Rio de Janeiro

Universidad Autonoma de Nuevo Leon

Department of Earth Sciences at Zhejiang University in China