Z. R. Dennis

Monash University

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J. P. Cull

Monash University

Toshihiro Uchida

National Institute of Advanced Industrial Science and Technology

Yoonho Song

Korea Institute of Geoscience and Mineral Resources

James Cull

Monash University

D. H. Moore

Monash University

In Hwa Park

Korea Institute of Geoscience and Mineral Resources

Seong Lee

Dankook University Hospital

R. A. Cayley

Geological Survey of Western Australia

Tae Jong Lee

SK Group (South Korea)

Seong Kon Lee

Korea Institute of Geoscience and Mineral Resources

Cooperative Institutions

Korea Institute of Geoscience and Mineral Resources

Geological Survey of Western Australia

Geoscience Australia

Monash University

Pusan National University

Yuhan University

National Institute of Advanced Industrial Science and Technology

Geological Survey of Japan

National Institute for Land and Infrastructure Management

Mineral Resources

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Lower crust and upper mantle electrical anisotropy in southeastern Australia

Exploration Geophysics (2012)

Z. R. Dennis Stephan Thiel James Cull

The dominant north–south strike of the Palaeozoic outcrop of central Victoria has been well documented, but to the north, these rocks are covered by the Cainozoic sedimentary deposits of the Murray Basin. Two magnetotelluric surveys were completed to assist in extrapolation of the known structure and to identify possible new targets for mineral discovery. Supporting the results from previous seismic interpretations for the region, the 2D MT inversion models substantiate an intrazone thrust fault system of listric geometries in the Bendigo Zone connected in the mid-crust. With the zone boundary clearly defined the electrical resistivity structure is distinct between the major subdivisions, indicating a different tectonic evolution for the Bendigo and Melbourne Zones. However, the conductive overburden in the region poses complications for the generation of the 2D resistivity models. Static shifts and electrical anisotropy were identified as distortions in the dataset, with further processing needed to attain a complete picture of the underlying geology. The difficulties caused by galvanic distortion were allayed by using the phase tensor response in place of the distorted amplitude response. Phase tensor analysis of MT data has been completed subsequently, the results of which we present here, along with the original 2D inversion models, confirming that electrical anisotropy persists into the mantle.

Magnetotellurics

Overburden

Outcrop

10.1071/eg11022

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Citations (9)

Transient electromagnetic surveys for the measurement of near-surface electrical anisotropy

Journal of Applied Geophysics (2011)

Z. R. Dennis J. P. Cull

Transient (computer programming)

10.1016/j.jappgeo.2011.10.014

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Transient electromagnetic profiles across gold-mineralisation zones in central Victoria

Australian Journal of Earth Sciences (2010)

Z. R. Dennis J. P. Cull R. A. Cayley

High-density transient electromagnetic (TEM) profiles have been obtained along a 170 km long transect in central Victoria north of Bendigo. The transect lies within two of the fault-bounded subdivisions of the western Lachlan Fold Belt (the Bendigo and Melbourne Zones) and coincides with part of a 2006 seismic-reflection traverse and a 2007 magnetotelluric (MT) survey commissioned by Geoscience Victoria as part of the Victorian Government's Gold Undercover initiative. In addition to providing near-surface information that will assist with geological mapping, the TEM survey also presents a viable method for the removal of static offsets present in the MT data. The new dataset also provides an immediate comparison and verification of data acquired along the same line by the helicopter-borne Versatile Transient Electromagnetic (VTEM) system. Ground-based data have been obtained for a total of 55 sites, and high-quality decay curves have revealed a variety of conductivity characteristics with typical penetration to depths of 100 m. Major geological structures can clearly be identified in both the ground and airborne sections, with very good lateral correlation present between the two. The fault zones are easily distinguished as regions characterised by bands of high conductivity along with significant variability in the near-surface structure.

Magnetotellurics

10.1080/08120091003619233

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Citations (3)

Magnetotelluric survey for undercover structural mapping, Central Victoria

Australian Journal of Earth Sciences (2011)

Z. R. Dennis D. H. Moore J. P. Cull

Over 2% of total world gold production has come from the Victorian gold fields; however, most of the shallow deposits have now been discovered, and new methods are required for exploration beneath the thick sedimentary cover of the Murray Basin. Consequently, as part of the GeoScience Victoria Gold Undercover Initiative, new magnetotelluric (MT) data have now been obtained to provide a greater understanding of potential gold bearing structures extending to mid-crustal and greater depths. Coinciding with part of the 2006 Central Victorian Seismic Survey, a 170 km long MT transect lies within the Bendigo and Melbourne Zones, two of the fault bounded subdivisions of the western Lachlan Fold Belt. Additional transient electromagnetic (TEM) data have now been obtained at each of the MT sites allowing further processing, including compensation for static shifts that are significant in this area. The revised MT section provides an image consistent with the seismic section. The major fault zones align with several dipping conductive slabs supporting the orientation and depth extent revealed by the seismic profile. There is some evidence in the MT data that near-surface geological structures can be extrapolated to mantle depths.

Magnetotellurics

Geological survey

10.1080/08120099.2011.534817

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Citations (15)

A geological interpretation of the Echuca magnetotelluric survey, Victoria

Australian Journal of Earth Sciences (2011)

Z. R. Dennis D. H. Moore J. P. Cull

The northern part of the auriferous Bendigo Zone is obscured by thick Cenozoic sediments of the Murray Basin, and as such remains poorly explored. Consequently, in addition to the 2006 deep seismic line obtained in Central Victoria, a magnetotelluric (MT) survey was completed to provide a signature for the major structures previously defined in the Bendigo area. Based on these correlations a second MT line, which we present here, was completed some 50 km to the north of the original line in an attempt to trace the deep structural trends extending north to the Victorian/NSW border. Extending some 155 km across the central north of the state, data were collected at 52 sites along an east–west profile. The new electrical conductivity model generated correlates well with the results from the southern transect; it confirms previously identified structural trends to the north and identifies additional unknown deep structures, thus adding to the understanding of the geology of the covered region and to its gold-bearing potential.

Magnetotellurics

10.1080/08120099.2011.577808

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Citations (4)

A magnetotelluric survey to the north of the 2006 central Victorian seismic transect: final report

Z. R. Dennis James Cull Seong Lee In-Wha Park Yoonho Song

Magnetotellurics

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Electrical conductivity structure from inversion analysis of magnetotelluric data acquired in northern Victoria, Australia

EGUGA (2010)