Is There a Speed Limit for the Thermal Steady‐State Assumption in Continental Rifts?

Heckenbach, Esther; Brune, Sascha; Glerum, Anne; Sippel, Judith

doi:10.1029/2020gc009577

Cited by 8 publications

(4 citation statements)

References 89 publications

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“…We perform numerical simulations of a 3D extensional system using the open source finite element code ASPECT (Advanced Solver for Problems in Earth's ConvecTion, version 2.1.0; Bangerth et al., 2019; Heister et al., 2017; Kronbichler et al., 2012; Rose et al., 2017). While this software was originally developed to study global mantle convection, it has successfully been adopted to model geodynamic processes of lithosphere deformation, in particular extensional tectonics (Heckenbach et al., 2021; Heron et al., 2019; Muluneh et al., 2020; Naliboff et al., 2020; Sandiford et al., 2021). ASPECT solves the following extended Boussinesq conservation equations assuming an infinite Prandtl number (i.e., without the inertial term),

- \nabla \cdot (2 η \overset{ε}{true}) + \nabla P = ρ g,

\nabla \cdot (bold-italicu) = 0,

\bar{ρ} C_{p} (\frac{\partial T}{\partial t} + u \cdot \nabla T) - \nabla \cdot k \nabla T = \bar{ρ} H + (2 η \overset{ε}{true}) : \dot{ε} + α T (u \cdot \nabla P),

\frac{\partial c_{i}}{\partial t} + u \cdot \nabla c_{i} = q_{i}

where Equation represents the conservation of momentum, with

η

the effective viscosity,

\dot{ε}

the deviator of the strain rate tensor (defined as

\frac{1}{2} (\nabla u + {(\nabla u)}^{T})

), u the velocity, P the...…”

Section: Methodsmentioning

confidence: 99%

Formation of Continental Microplates Through Rift Linkage: Numerical Modeling and Its Application to the Flemish Cap and Sao Paulo Plateau

Neuharth

Brune

Glerum

et al. 2021

Geochem Geophys Geosyst

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Continental microplates are enigmatic plate boundary features, which can occur in extensional and compressional regimes. Here we focus on microplate formation and their temporal evolution in continental rift settings. To this aim, we employ the geodynamic finite element software ASPECT to conduct 3D lithospheric‐scale numerical models from rift inception to continental breakup. We find that depending on the strike‐perpendicular offset and crustal strength, rift segments connect or interact through one of four regimes: (1) an oblique rift, (2) a transform fault, (3) a rotating continental microplate or (4) a rift jump. We highlight that rotating microplates form at offsets >200 km in weak to moderately strong crustal setups. We describe the dynamics of microplate evolution from initial rift propagation, to segment overlap, vertical‐axis rotation, and eventually continental breakup. These models may explain microplate size and kinematics of the Flemish Cap, the Sao Paulo Plateau, and other continental microplates that formed during continental rifting worldwide.

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- \nabla \cdot (2 η \overset{ε}{true}) + \nabla P = ρ g,

\nabla \cdot (bold-italicu) = 0,

\bar{ρ} C_{p} (\frac{\partial T}{\partial t} + u \cdot \nabla T) - \nabla \cdot k \nabla T = \bar{ρ} H + (2 η \overset{ε}{true}) : \dot{ε} + α T (u \cdot \nabla P),

\frac{\partial c_{i}}{\partial t} + u \cdot \nabla c_{i} = q_{i}

where Equation represents the conservation of momentum, with

η

the effective viscosity,

\dot{ε}

the deviator of the strain rate tensor (defined as

\frac{1}{2} (\nabla u + {(\nabla u)}^{T})

), u the velocity, P the...…”

Section: Methodsmentioning

confidence: 99%

Formation of Continental Microplates Through Rift Linkage: Numerical Modeling and Its Application to the Flemish Cap and Sao Paulo Plateau

Neuharth

Brune

Glerum

et al. 2021

Geochem Geophys Geosyst

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show abstract

“…Parameters are listed in Table 1. Here, we build on previous ASPECT setups that were designed to capture rift dynamics on a wide range of scales (Corti et al., 2019; Glerum et al., 2020; Heckenbach et al., 2021; Muluneh et al., 2020; Neuharth et al., 2021; Sandiford et al., 2021).…”

Section: Numerical Model Setupmentioning

confidence: 99%

Controls on Asymmetric Rift Dynamics: Numerical Modeling of Strain Localization and Fault Evolution in the Kenya Rift

et al. 2021

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Asymmetric rifting, which is characterized by a dominant single border fault, is known to have played a major role in the evolution of many past rift systems (e.g., Schlische et al., 2003;Withjack et al., 2013). It can also be observed in many presently active extensional tectonic settings (e.g., Gawthorpe & Leeder, 2008;Ebinger & Scholz, 2011), where it governs basin geometry, topography evolution, erosion, and sedimentation patterns. One such setting is the largest continental rift system in existence today: the East African Rift System (EARS). It exhibits a wide array of developmental stages from youthful extension with incipient faulting to final continental breakup (Corti, 2009;Ebinger & Scholz, 2011;Ring, 2014) and is thus an ideal location for studying the stages of early rifting that involve asymmetric normal fault activity followed by hanging-wall segmentation. In this study, we focus on the southern and central sectors of the Kenya Rift, which are in an early phase of active continental rifting (Ebinger et al., 2017) characterized by the transition from waning border fault activity to enhanced intra-basinal faulting and subsidence (Muirhead et al., 2016).The first-order tectonic characteristics of continental rifts are known to be influenced by a large range of structural, petrological, and thermal parameters, which have been investigated in previous numerical modeling studies (e.g.,

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“…Numerical models were conducted using the finite element software ASPECT (Heister et al., 2017; Kronbichler et al., 2012; Rose et al., 2017), which solves the conservation equations of momentum, mass and energy for materials with visco‐plastic rheology (Glerum et al., 2018). This software has previously been successfully applied to model rift tectonics, both in two (Heckenbach et al., 2021; Neuharth et al., 2022; Richter et al., 2021) and three dimensions (Corti et al., 2019; Glerum et al., 2020; Gouiza & Naliboff, 2021; Naliboff et al., 2020).…”

Section: Methodology and Modeling Strategymentioning

confidence: 99%

Analog and Numerical Modeling of Rift‐Rift‐Rift Triple Junctions

et al. 2022

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Triple junctions involve the movement of three tectonic plates, and therefore represent one of the most challenging settings to understand deformation processes (e.g., Kleinrock & Morgan, 1988;McKenzie & Morgan, 1969;Patriat & Courtillot, 1984). McKenzie and Morgan (1969) identified 16 possible cases of triple junctions, among which the only stable case for all velocity conditions is the extensional Ridge-Ridge-Ridge triple junction (RRR), in which the three plates move away from each other. For this reason, RRR junctions can be preserved independent of the individual extension directions, and therefore they may exhibit symmetrical settings (with rift branches at 120°) as well as extremely asymmetric geometries.

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Is There a Speed Limit for the Thermal Steady‐State Assumption in Continental Rifts?

Cited by 8 publications

References 89 publications

Formation of Continental Microplates Through Rift Linkage: Numerical Modeling and Its Application to the Flemish Cap and Sao Paulo Plateau

Formation of Continental Microplates Through Rift Linkage: Numerical Modeling and Its Application to the Flemish Cap and Sao Paulo Plateau

Controls on Asymmetric Rift Dynamics: Numerical Modeling of Strain Localization and Fault Evolution in the Kenya Rift

Analog and Numerical Modeling of Rift‐Rift‐Rift Triple Junctions

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