Precambrian deformation belts in compressive tectonic regimes: A numerical perspective

Poh, Jonathan; Yamato, Philippe; Duretz, Thibault; Gapais, Denis; Ledru, Patrick

doi:10.1016/j.tecto.2020.228350

Cited by 12 publications

(16 citation statements)

References 86 publications

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“…(A6) is satisfied (e.g. Popov and Sobolev, 2008). The viscosity for the dislocation and Peierls creep flow law is a function of the second invariant of the respective strain rate componentsε Figure A1.…”

Section: Discussionmentioning

confidence: 98%

Impact of upper mantle convection on lithosphere hyperextension and subsequent horizontally forced subduction initiation

2020

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Abstract. Many plate tectonic processes, such as subduction initiation, are embedded in long-term (>100 Myr) geodynamic cycles often involving subsequent phases of extension, cooling without plate deformation and convergence. However, the impact of upper mantle convection on lithosphere dynamics during such long-term cycles is still poorly understood. We have designed two-dimensional upper-mantle-scale (down to a depth of 660 km) thermo-mechanical numerical models of coupled lithosphere–mantle deformation. We consider visco–elasto–plastic deformation including a combination of diffusion, dislocation and Peierls creep law mechanisms. Mantle densities are calculated from petrological phase diagrams (Perple_X) for a Hawaiian pyrolite. Our models exhibit realistic Rayleigh numbers between 106 and 107, and the model temperature, density and viscosity structures agree with geological and geophysical data and observations. We tested the impact of the viscosity structure in the asthenosphere on upper mantle convection and lithosphere dynamics. We also compare models in which mantle convection is explicitly modelled with models in which convection is parameterized by Nusselt number scaling of the mantle thermal conductivity. Further, we quantified the plate driving forces necessary for subduction initiation in 2D thermo-mechanical models of coupled lithosphere–mantle deformation. Our model generates a 120 Myr long geodynamic cycle of subsequent extension (30 Myr), cooling (70 Myr) and convergence (20 Myr) coupled to upper mantle convection in a single and continuous simulation. Fundamental features such as the formation of hyperextended margins, upper mantle convective flow and subduction initiation are captured by the simulations presented here. Compared to a strong asthenosphere, a weak asthenosphere leads to the following differences: smaller value of plate driving forces necessary for subduction initiation (15 TN m−1 instead of 22 TN m−1) and locally larger suction forces. The latter assists in establishing single-slab subduction rather than double-slab subduction. Subduction initiation is horizontally forced, occurs at the transition from the exhumed mantle to the hyperextended passive margin and is caused by thermal softening. Spontaneous subduction initiation due to negative buoyancy of the 400 km wide, cooled, exhumed mantle is not observed after 100 Myr in model history. Our models indicate that long-term lithosphere dynamics can be strongly impacted by sub-lithosphere dynamics. The first-order processes in the simulated geodynamic cycle are applicable to orogenies that resulted from the opening and closure of embryonic oceans bounded by magma-poor hyperextended rifted margins, which might have been the case for the Alpine orogeny.

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Section: Discussionmentioning

confidence: 98%

Impact of upper mantle convection on lithosphere hyperextension and subsequent horizontally forced subduction initiation

2020

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“…Numerical models suggest that transitional tectonics occurred at mantle temperature up to 200 • C higher than today and was triggered by the generation of continental crust and the stabilisation of cratons (e.g., Sizova et al, 2010Sizova et al, , 2015Perchuk et al, 2018). However, a recent thermo-mechanical study indicated that the shortening rate, which can vary over several orders of magnitude, also plays an important role (Poh et al, 2020). High shortening rates ( > 1 × 10 -15 s -𝜀 𝐵𝐺 1 ) favours the formation of asymmetric deformation zones (i.e., modern-style tectonics) while low shortening rates ( < 1 × 10 -15 s -1 ) favour the development of 𝜀 𝐵𝐺 distributed deformation zones and vertical structures (i.e., ancient-style tectonics).…”

Section: Strength Of the Lithosphere And Parameters To Testmentioning

confidence: 99%

The transition from ancient to modern-style tectonics: Insights from lithosphere dynamics modelling in compressional regimes

et al. 2021

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“…The regional strain field (Fig. 5d), characterized by steeply dipping anastomosing fault systems that extend over several hundred kilometres along strike, is interpreted as resulting from the horizontal shortening and vertical stretching of a weak lithosphere during Paleoproterozoic orogens (Gapais, 2018;Poh et al, 2020;Ledru et al, 2022). In this model, deeply rooted structures like the Wollaston-Mudjatik Transition Zone, the Snowbird Tectonic Zone/Virgin River shear zone and the Patterson Lake corridor, are responsible of crustal segmentation and are natural links between deep and shallow processes.…”

Section: Sedimentary Basin-related Hydrothermal Mineralization Systemsmentioning

confidence: 99%

Hydrodynamic Links between Shallow and Deep Mineralization Systems and Implications for Deep Mineral Exploration

Chi

Xue

et al. 2022

Acta Geologica Sinica (Eng)

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Deep mineral exploration is increasingly important for finding new mineral resources but there are many uncertainties. Understanding the factors controlling the localization of mineralization at depth can reduce the risk in deep mineral exploration. One of the relatively poorly constrained but important factors is the hydrodynamics of mineralization. This paper reviews the principles of hydrodynamics of mineralization, especially the nature of relationships between mineralization and structures, and their applications to various types of mineralization systems in the context of hydrodynamic linkage between shallow and deep parts of the systems. Three categories of mineralization systems were examined, i.e., magmatic‐hydrothermal systems, structurally controlled hydrothermal systems with uncertain fluid sources, and hydrothermal systems associated with sedimentary basins. The implications for deep mineral exploration, including potentials for new mineral resources at depth, favorable locations for mineralization, as well as uncertainties, are discussed.

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Precambrian deformation belts in compressive tectonic regimes: A numerical perspective

Cited by 12 publications

References 86 publications

Impact of upper mantle convection on lithosphere hyperextension and subsequent horizontally forced subduction initiation

Impact of upper mantle convection on lithosphere hyperextension and subsequent horizontally forced subduction initiation

The transition from ancient to modern-style tectonics: Insights from lithosphere dynamics modelling in compressional regimes

Hydrodynamic Links between Shallow and Deep Mineralization Systems and Implications for Deep Mineral Exploration

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