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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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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)
PublisherNatural Resources Canada
Documentopen file
Mediaon-line; digital
RelatedThis publication is contained in Rogers, N; (2019). Targeted Geoscience Initiative: 2018 report of activities, Geological Survey of Canada, Open File 8549
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.