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Type: Thesis
Title: The use of 3D magnetotellurics in mineral exploration: synthetic model study and inversion of 3D MT survey data from the Wirrda Well IOCG (SA, Australia)
Author: Komenza, J. D.
Issue Date: 2013
School/Discipline: School of Physical Sciences
Abstract: As a consequence of diminishing shallow mineral resources, the exploration industry has turned its focus to deeper targets. For this reason, the magnetotelluric (MT) method has gained much attention due to its unique penetration in regions of thick cover sequences. As the setting and geometries of mineral deposits are often complex, three-dimensional (3D) models are required for their interpretation. Though still computationally demanding, 3D inversion is now becoming a practical and common tool for presenting MT data. However, there has been little critical analysis of the ability of 3D MT surveys to recover structural geometry. To assess the value of 3D MT in the exploration of mineral deposits, this study compares results of synthetic model studies with a 3D MT survey from an iron oxide copper gold (IOCG) deposit in South Australia. Synthetic data sets are presented for two scenarios incorporating a conductive 3D target, with and without conductive cover. A comparison of model responses demonstrate that while MT is greatly sensitive to conductive and symmetrical bodies at depth, its resolution for detecting finite 3D bodies is significantly reduced under conductive cover. Although 2D inversions can recover the geometry of finite conductive bodies, it is possible to successfully interpret 2D survey data using 3D inversion algorithms. Utilising all components of the impedance tensor, off-profile 3D conductive structure can be obtained from 2D survey data alone. Results of the synthetic studies were applied to a 3D MT data set acquired across the Wirrda Well IOCG deposit (SA, South Australia). Although the thickness of conductive cover sequences were resolved from 2D and 3D inversion, conductivity structure associated with alteration and mineralisation could not be recovered. Thus, although 3D MT shows promise for recovering 3D conductivity structures at depth, its use in delineating deposit scale targets under conductive cover is greatly limited.
Dissertation Note: Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2013
Where: Olympic Domain, Gawler Craton, South Australia
Keywords: Honours; Geology; magnetotellurics; mineral exploration; two dimensional inversion; three-dimensional inversion; synthetic model studies; Wirrda Well; IOCG
Description: This item is only available electronically.
Provenance: This electronic version is made publicly available by the University of Adelaide in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. This thesis may incorporate third party material which has been used by the author pursuant to Fair Dealing exceptions. If you are the author of this thesis and do not wish it to be made publicly available, or you are the owner of any included third party copyright material you wish to be removed from this electronic version, please complete the take down form located at:
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