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  • 1
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    Dike propagation through an elastic plate (1998)
    In:  J. Geophys. Res., Kalamazoo, Michigan 49001, The Upjohn Company, vol. 103, no. B8, pp. 18,295-18,324, pp. L09603, (ISSN: 1340-4202)
    Details
    Publication Date: 1998
    Keywords: Elasticity ; Volcanology ; 8434 ; Volcanology ; Magma ; migration ; 8145 ; Tectonophysics ; JGR ; Physics ; of ; magma ; and ; magma ; bodies ; 8414 ; Eruption ; mechanisms
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    BIBLIOGRAPHY SEISMOLOGY
  • 2
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    Simple fluid dynamic models of volcanic rift zones (1995)
    In:  Earth planet. Sci. Lett., Luxembourg, Conseil de l'Europe, vol. 136, no. 1, pp. 223-240, pp. L24314, (ISSN: 1340-4202)
    Details
    Publication Date: 1995
    Keywords: Modelling ; Volcanology
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    BIBLIOGRAPHY SEISMOLOGY
  • 3
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    Slip and creep deformation in a strike-slip shear zone (2002)
    In:  Geophys. J. Int., Oslo, Wiley, vol. 148, no. 2, pp. 179-192, pp. B08303, (ISSN: 1340-4202)
    Details
    Publication Date: 2002
    Keywords: Crustal deformation (cf. Earthquake precursor: deformation or strain) ; Geothermics ; StressS ; Strike-slip ; Rheology ; Two-dimensional ; GJI
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    BIBLIOGRAPHY SEISMOLOGY
  • 4
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    Temperature and rheological properties of the mantle beneath the North American craton from an analysis of heat flux and seismic data (2011)
    Wiley
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    Publication Date: 2011-01-26
    Description: We combine heat flux data and seismic velocity models for the North American lithosphere to derive constraints on thermal conditions and deformation mechanisms in the underlying convecting mantle. Local heat flux averages that are not affected by shallow crustal heat production contrasts allow calculation of reliable lithospheric geotherms and uncertainty ranges. For consistency with the seismic data, the mantle potential temperature beneath North America must lie within a 1290°C–1450°C range, close to that for the oceanic mantle sampled at mid-ocean ridges. The heat flux at the base of the lithosphere varies laterally from 11 ± 3 mW m−2 beneath the ∼250 km thick Archean core of the Superior province to 15 ± 3 mW m−2 beneath the thinner younger Appalachians province. It is shown that the most likely cause of such rates of heat supply into the North American continent is small-scale convection in an unstable boundary layer beneath the rigid mechanical lithosphere. This allows useful constraints on the mantle rheological properties. We show that the most likely deformation mechanism is dislocation creep in wet mantle rocks. Ranges for the mantle temperature, water content, and rheological parameters could be tightened very significantly once strong constraints are obtained on radiogenic heat production in the lithospheric mantle.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 5
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    Folding in regions of extension (2011)
    Oxford University Press
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    Publication Date: 2011-04-15
    Description: SUMMARY Many extension zones have been subjected to folding and shortening in a direction perpendicular to the stretching. Such deformation can be accounted for by the extension of a thin superficial elastic layer overlying a substrate that has small elastic moduli or that deforms in a viscous regime. Laboratory experiments are used to document the wavelength and amplitude of the folds for a range of geometrical configurations. Folding is observed even for very small amounts of extension (less than 1 per cent) with characteristics that are consistent with finite-amplitude scaling laws. Because of the intrinsically 3-D nature of the deformation field, the size of the region affected by folding and the direction of the fold axes depend on the orientation of the extension with respect to the rigid blocks that bound the deforming region. For regions of extension where the elastic thickness is about 10 km, as in the Basin and Range province for example, it is predicted that folding occurs with wavelengths in a 20–40 km range, such that it induces little deformation in the lower crust and maintains a flat Moho discontinuity. These predictions are consistent with the observations. The characteristics of faulting that is associated with such deformation are discussed.
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
    Published by Oxford University Press on behalf of The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).
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  • 6
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    The initiation of subduction by crustal extension at a continental margin (2012)
    Oxford University Press
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    Publication Date: 2012-01-07
    Description: SUMMARY We investigate how subduction may be triggered by continental crust extension at a continental margin. The large topography contrast between continental and oceanic domains drives the spreading of continental crust over oceanic basement. Subduction requires the oceanic plate to get submerged in mantle, so that negative buoyancy forces may take over and drive further descent. This is promoted by two mechanisms. Loading by continental crust bends the oceanic plate downwards. Extension in the continental domain induces crustal thinning, which acts to raise mantle above the oceanic plate. In this model, the width of the continental region undergoing extension is an important control parameter. The main physical controls are illustrated by laboratory experiments and simple theory for elastic flexure coupled to viscous crustal spreading. Three governing dimensionless parameters are identified. One involves the poorly constrained oceanic plate buoyancy. We find that the oceanic plate can be thrust to depths larger than 40 km even if it is buoyant, enabling metamorphic reactions and density increase in the oceanic crust. Another parameter is the ratio between the width of the continental extension region and the flexural parameter for the oceanic plate. Initiating subduction is easier if the continent thins over a short lateral distance or if the oceanic plate is strong. The third important parameter is the ratio of oceanic plate thickness to initial continental crust thickness, such that a weak plate and a thick crust do not favour subduction. Thus, the change from a passive to an active margin depends on the local characteristics of the continental crust and is not determined solely by the age and properties of the oceanic lithosphere. It is shown that the spreading of continental crust induces uplift of the margin as the adjacent seafloor subsides. Evidence for the emplacement of continental crust over oceanic basement at passive margins is reviewed.
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
    Published by Oxford University Press on behalf of The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).
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  • 7
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    The Building and Stabilization of an Archean Craton in the Superior Province, Canada, From a Heat Flow Perspective (2014)
    Wiley
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    Publication Date: 2014-11-14
    Description: How continental lithosphere responds to tectonic stresses and mantle convective processes is determined in large part by its mechanical strength and temperature distribution, which depend on crustal heat production. In order to establish reliable crustal and thermal models for the Superior craton, Canadian Shield, new measurements of heat flux and heat production in 28 deep boreholes at 16 sites are combined with a larger set of older data. The Superior Province was assembled by the docking of volcanic/plutonic and metasedimentary terranes and continental fragments to the southern margin of an older core around 2.7 Ga. The average heat flux is much lower in the craton core than in the accreted terranes, 31 versus 43 mWm -2 . The major accreted volcanic/plutonic belts share the same heat production characteristics, testifying to the remarkable uniformity of crust-building mechanisms. The marked difference between the crusts of the core and the accreted belts supports the operation of two different crust-forming processes. The crust of the craton core has an enriched upper layer, in contrast to that of the younger belts which lack marked internal differentiation. At the end of amalgamation, the lithosphere of the craton core was colder and mechanically stronger than the lithosphere beneath newly accreted material. Surrounding the craton core with weaker belts may have ensured its stability against tectonic and mantle convection perturbations. This large strength contrast accounts for the lack of lithospheric imbrication at the edge of the craton core as well as for the different characteristics of seismic anisotropy in the lithospheres of the craton core and the younger terranes.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 8
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    Post-Emplacement Dynamics of Basaltic Intrusions In the Continental Crust (2017)
    Wiley
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    Publication Date: 2017-02-08
    Description: Laboratory experiments document the post-emplacement behaviour of mafic intrusions that spread at a density interface and founder as they become denser than their surroundings due to cooling and crystallization. All else being equal, the larger the intrusion volume, the farther the intrusion can spread and the smaller its aspect ratio is. The final aspect ratio is a function of a single dimensionless number analogous to the Rayleigh number of thermal convection. Once it is denser than its surroundings, the intrusion becomes unstable and may founder in two different regimes. At aspect ratios larger than about 0.4, the “teardrop” regime is such that the intrusion thickens in a central region, developing the shapes of a funnel and a pendant drop. At lower aspect ratios, another regime is observed, with thickening of the intrusion at the leading edge and thinning in a central region. The thick outer ring in turn becomes unstable into a set of teardrops and leads to an irregular horizontal outline. In one variant called the “jellyfish” regime, the thin central region develops a number of downwellings and upwellings in a Rayleigh-Taylor-like pattern. These instabilities may get arrested due to cooling as the intrusion and encasing rocks become too strong to deform. One would then be left with a funnel shaped residual body or a wide irregular one with thick peripheral lobes and a thinner central region. These different patterns can be recognized in upper crustal mafic intrusions.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 9
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    The instability of continental passive margins and its effect on continental topography and heat flow (2013)
    Wiley
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    Publication Date: 2013-01-22
    Description: [1]  The long geological history of passive margin evolution is complex yet typified by an initial ramp-like tilting of the subaerial surface towards the continent-ocean boundary, followed by episodic uplift and subsidence at a smaller wavelength. We argue that this behaviour is due to changes in margin structure brought about by buoyancy-driven lithospheric flow. Continental lithosphere is melt-depleted, buoyant and thick. It will resist convective breakdown into the asthenosphere below, but will be prone to lateral flow due to horizontal density contrasts. Changes in lithosphere thickness at the transition between continent and ocean will nucleate convection cells. Using a numerical model of viscous upper mantle flow we show that stability or instability of the continental lithosphere at a passive margin is a function of the lithospheric rheology and composition. Increased compositional buoyancy leads to ocean-ward lateral flow of the continental lithosphere whereas decreased buoyancy has the opposite effect, causing landward lateral flow of the continental lithosphere. In model simulations, a continental lithosphere thought typical of Phanerozoic continental platforms experiences first a margin-wide ramp-like tilting, followed by topographic fluctuations due to an evolving array of convection cells in the mantle. The timing and magnitude of predicted changes in topography are similar to those observed at the eastern North American margin, suggesting that the tilting and episodic uplift and subsidence at continental passive margins are a natural consequence of the evolution of continental lithosphere after break-up and during mature sea-floor spreading.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 10
    Electronic Resource
    Electronic Resource
    Editorial (2000)
    Oxford, UK : Blackwell Science Ltd
    Terra nova 12 (2000), S. 0 
    Details
    ISSN: 1365-3121
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3121.2000.00284.x
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    Paper (German National Licenses)
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