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TitleResolution and uncertainty in lithospheric 3-D geological models
AuthorSnyder, D BORCID logo; Schetselaar, E; Pilkington, M; Schaeffer, A JORCID logo
SourceMineralogy and Petrology vol. 112, issue S1, 2018 p. S133-S147,
Alt SeriesEarth Sciences Sector, Contribution Series 20150488
PublisherSpringer Nature
Mediapaper; on-line; digital
File formatpdf
ProgramGEM2: Geo-mapping for Energy and Minerals Geological Map Flow
Released2018 08 15
AbstractAs three-dimensional (3-D) modelling of the subcontinental mantle lithosphere is increasingly performed with ever more data and better methods, the robustness of such models is increasingly questioned. Resolution thresholds and uncertainty within deep multidisciplinary 3-D models based on geophysical observations exist at a minimum of three levels. Seismic waves and potential field measurements have inherent limitations in resolution related to their dominant wavelengths. Formal uncertainties can be assigned to grid-search type forward or inverse models of observable parameter sets. Both of these uncertainties are typicallyminor when compared to resolution limitations related to the density and shape of a specific observation array used in seismological or potential field surveys. Seismic wave source distribution additionally applies in seismology. A fourth, more complex level of uncertainty relates to joint inversions of multiple data sets. Using independent seismic wave phases or combining diverse methods provides another measure of uncertainty of particular physical properties. Extremely sparse xenolith suites provide the only direct correlation of rock type with observed ormodelled physical properties at depths greater than a few kilometers. Here we present one case study of the Canadian Mohorovi?i? (Moho) discontinuity using only two data sets. Refracted and converted seismic waves formthe primary determinations of the Moho depth, gravity fieldmodeling provide a secondary constraint on lateral variations, the slope of the Moho, between the sparse seismic estimates. Although statistically marginal, the resulting co-kriged Moho surface correlates better with surface geology and is thus deemed superior.
Summary(Plain Language Summary, not published)
The Open Geoscience program has embarked on a 2-year pilot study to assess the practicality of building a digital 3-D geological map of Canada. The deep layers of this model will depend almost entirely on geophysical observations. This paper discusses uncertainties associated with these observations as well as estimating the resolution possible with geophysical models today. Discussion also includes uncertainties associated with mapping geophysical properties into geological models. This all underpins the reliability and confidence users can have in a 3-D model of Canada.

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