Uncertainties in crustal thickness models for data sparse environments: A review for South America and Africa

Meijde, M. van der; Fadel, Islam; Ditmar, Pavel; Hamayun, M.

doi:10.1016/j.jog.2014.09.013

Cited by 26 publications

(11 citation statements)

References 44 publications

(53 reference statements)

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“…Assuming that they are uncorrelated, then their total contribution to the elevation anomaly is ~±0.7 km at the 1 sigma level, but it could be much higher if they are systematically correlated, acting in the same direction and extending over wide areas. For example, studies using different methodologies suggest that CRUST 1.0 may systematically overpredict the thickness of the crust by up to ~5 km in significant parts of South America and Africa (Figures 9 and S3; Van der Meijde et al, 2015).…”

Section: Factors Controlling Deviations From Global Wli Model (Data Smentioning

confidence: 99%

Global Whole Lithosphere Isostasy: Implications for Surface Elevations, Structure, Strength, and Densities of the Continental Lithosphere

Lamb

Moore

Pérez‐Gussinyé

et al. 2020

Geochem Geophys Geosyst

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The observed variations in the thickness of the conductive lithosphere, derived from surface wave studies, have a first-order control on the elevation of the continents, in addition to variations in the thickness of the crust-this defines whole lithosphere isostasy (WLI). Negative buoyancy of the mantle lithosphere counters the positive buoyancy of the crust, and together, their respective thicknesses and density contrasts determine elevation of the continents both in their interiors and at their edges. The average density contrasts for lithospheric mantle with crust and with asthenosphere are typically 300 to 550 and 20 to 40 kg m −3 , respectively, with a ratio 10 to 16, suggesting moderate average depletion of lithospheric mantle. We show that a crustal model for Antarctica, assuming WLI and using these density contrasts, provides a close fit to estimates of crustal thickness from surface wave tomography and gravity observations. We use a global model of WLI as a framework to assess factors controlling topography, showing that plausible regional variations in crustal and mantle densities, together with uncertainties in the crustal and conductive lithospheric thicknesses, are sufficient to account for global elevations without invoking dynamic topography greater than a few hundred meters. Estimates of elastic thickness T e in the continents are typically 25-50% of the thickness of the conductive lithosphere, indicating that the mantle part supports some of the elastic strength of the lithosphere.

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Section: Factors Controlling Deviations From Global Wli Model (Data Smentioning

confidence: 99%

Global Whole Lithosphere Isostasy: Implications for Surface Elevations, Structure, Strength, and Densities of the Continental Lithosphere

Lamb

Moore

Pérez‐Gussinyé

et al. 2020

Geochem Geophys Geosyst

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“…With the advent of satellite gravimetry missions like GRACE and GOCE, gravity-derived crustal models can be produced in regional or global scales (e.g. Reguzzoni et al 2013;van der Meijde et al 2013van der Meijde et al , 2015. New spherical harmonic gravity models that use these satellite observation, like GOCO5S (Mayer-Guerr et al 2015), provide almost homogeneous data coverage in difficult to access regions traditionally poor in terrestrial data.…”

Section: Introductionmentioning

confidence: 99%

Fast nonlinear gravity inversion in spherical coordinates with application to the South American Moho

2016

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“…Such complicated fault histories are likely to occur on several other faults as well. Previous studies have suggested several stages of movement history along the Kimberley Fault, acting on an early graben system transfer feature, overprinted by local Laramide folding and reverse dextral motion and later dominant sinistral transcurrent (Eocene) motion (Turner et al, 2000). Identification of the Sullivan Mine stratigraphy north of the Kimberley Fault makes this early graben-related link for the Kimberley Fault impossible.…”

Section: Discussion/models Structural Analysis and Modelingmentioning

confidence: 99%

Assessing the workflow for regional-scale 3D geologic modeling: An example from the Sullivan time horizon, Purcell Anticlinorium East Kootenay region, southeastern British Columbia

et al. 2016

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We have developed a regional-scale 3D geologic model, highlighting the Mesoproterozoic Sullivan time horizon (approximately 1470 Ma) throughout the Purcell Anticlinorium in the East Kootenay region. This 3D geospatial model of the region is constrained with an extensive surface and subsurface database of stratigraphic, structural, and geophysical observations distributed throughout the study area. This modeling exercise was conducted over a four-year period from 2011 to 2015 in which several iterations of the model were produced. The final model includes what is locally referred to as the Lower-Middle Aldridge stratigraphic contact (LMC), a map unit at the very top of the lower Aldridge Formation where the Sullivan world-class Pb-Zn-Ag deposit is located. Local mineral exploration initiatives focus on this key exploration target horizon, which is now modeled in 3D. The regional LMC model provides a much needed geospatial reference used to characterize and understand sedimentary exhalative, a type of ore deposit (SEDEX) ore systems as well as a key 3D exploration target. Developing regional 3D geologic models for orogenic interiors such as the Purcell region, and older shield regions is a challenge. This is largely due to data sparsity at depth, lack of standards for 3D data collection, storage, integration, and interpretation practice. Current algorithms use only a partial set of available observational or knowledge constraints and exist in workflows that do not allow for complicated geologic event histories. We have mitigated some of these challenges with a new implicit algorithm (SURFE), applied in this Purcell case study, to estimate major regional faults and horizons through variably distributed and clustered data. These modeled geologic elements are then fed into the SKUA structural and stratigraphic workflow to produce the volumetric model. Reflection on the general 3D modeling workflow for these regional situations highlights the need for embedding more knowledge constraints into the process.

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Uncertainties in crustal thickness models for data sparse environments: A review for South America and Africa

Cited by 26 publications

References 44 publications

Global Whole Lithosphere Isostasy: Implications for Surface Elevations, Structure, Strength, and Densities of the Continental Lithosphere

Global Whole Lithosphere Isostasy: Implications for Surface Elevations, Structure, Strength, and Densities of the Continental Lithosphere

Fast nonlinear gravity inversion in spherical coordinates with application to the South American Moho

Assessing the workflow for regional-scale 3D geologic modeling: An example from the Sullivan time horizon, Purcell Anticlinorium East Kootenay region, southeastern British Columbia

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