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TitleThree-dimensional forward modelling and inversion of magnetotelluric data using unstructured meshes for understanding realistic geological systems: method development, algorithms and model construction for the Lalor deposit, Manitoba
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LicencePlease note the adoption of the Open Government Licence - Canada supersedes any previous licences.
AuthorAnsari, S M; Craven, J A; Schetselaar, E
SourceTargeted Geoscience Initiative: 2018 report of activities; by Rogers, N (ed.); Geological Survey of Canada, Open File 8549, 2019 p. 217-234, Open Access logo Open Access
PublisherNatural Resources Canada
Documentopen file
Mediaon-line; digital
RelatedThis publication is contained in Targeted Geoscience Initiative: 2018 report of activities
File formatpdf
AreaSnow Lake
Lat/Long WENS-100.2000 -100.1000 54.9000 54.8500
Subjectseconomic geology; geophysics; structural geology; stratigraphy; mineral deposits; base metals; volcanogenic deposits; sulphide deposits; mineral exploration; prospecting techniques; modelling; geophysical interpretations; magnetotelluric interpretations; electrical resistivity; conductivity; bedrock geology; structural features; faults; faults, thrust; lithostratigraphy; Archean; Lalor Deposit; ore systems approach; volcanogenic massive sulphide (VMS) deposits; geological mapping techniques; 3D modelling; algorithms; methodology; mesh-based models; forward modelling; data inversion; apparent resistivity; Paleoproterozoic; Precambrian; Proterozoic
Illustrationscross-sections; 3-D models; plots; geoscientific sketch maps; graphs; models
ProgramTargeted Geoscience Initiative (TGI-5), Knowledge Management Coordination
ProgramTargeted Geoscience Initiative (TGI-5), Volcanogenic massive sulphide ore systems - base metal sources and processes
Released2019 03 01
AbstractThe work presented here covers three major branches of geophysical prospecting including the development of model construction routines for realistic subsurface structures, forward modelling and magnetotelluric inversion strategies. Using a combination of tools, a routine is developed that produces a sealed model using tessellated geological surfaces representing lithostratigraphic contacts between rock units of the Lalor VMS deposit. This model is suitable for generating volumetric tetrahedral meshes required for mesh-based modelling and inversion of geophysical data. A finite-element based forward modelling technique is developed that discretizes the magnetotelluric problem on un-structured tetrahedral meshes. These meshes are suitable for producing realistic complex-shaped features. Magnetotelluric responses for the Lalor model are successfully calculated. A model space minimum-structure inversion is developed that is based on the iterative Gauss-Newton approach using sensitivity matrix-vector products calculated implicitly by finite-element based forward and pseudo-forward solutions.
Summary(Plain Language Summary, not published)
The Targeted Geoscience Initiative (TGI) is directed towards providing next generation knowledge and methods to facilitate more effective targeting of buried mineral deposits. The program aims to enhance the effectiveness of exploration for Canada's major mineral systems by resolving foundational geoscience problems that constrain the geological processes responsible for the liberation metals from their source region, transportation of these ore metals and control their eventual deposition. TGI supports projects on gold, Ni-Cr-PGE, porphyry-style mineralization, uranium and volcanic- and sedimentary-hosted base metal mineralization ore systems, with each project divided into subprojects focused on resolving specific knowledge gaps by integrating data and studies from multiple sites across Canada. Herein, we present interim results and interpretations from a selection of the research activities currently being conducted under the auspices of TGI.

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