Victoria continental microplate dynamics controlled by the lithospheric strength distribution of the East African Rift

Glerum, Anne; Brune, Sascha; Stamps, D. S.; Strecker, Manfred R.

doi:10.1038/s41467-020-16176-x

Cited by 51 publications

(54 citation statements)

References 104 publications

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“…Pronounced thinning occurred on both sides of the microplate from two coexisting rifts, with an oceanward rift jump rendering the landward rift obsolete. Early rift geometries and interactions in the microplate models resemble the East African Rift System and show that overlapping rifts with a rotating microplate can form without the guidance of lithospheric strength heterogeneities (e.g., mobile belts; Glerum et al., 2020). Additionally, the reference model elucidates many features of the Flemish Cap and Sao Paulo Plateau, two extensional microplates that formed during the rifting of the North and South Atlantic, respectively.…”

Section: Discussionmentioning

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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Section: Discussionmentioning

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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“…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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“…We construct a 2-D box setup using thermomechanical finite element code ASPECT v2.0.0-pre (Advanced Solver for Problems in the Earth's ConvecTion, Bangerth et al, 2018;Glerum et al, 2018;Heister et al, 2017;Kronbichler et al, 2012;Rose et al, 2017) to model extension of the MER. Our model is based on previous ASPECT setups aimed at modeling continental rift dynamics (Corti et al, 2019;Glerum et al, 2020;Naliboff et al, 2020). We solve the incompressible flow equations for conservation of momentum (Equation 1), mass (Equation 2), and energy (Equation 3) assuming an infinite Prandtl number:…”

Section: Governing Equationsmentioning

confidence: 99%

“…We construct a 2‐D box setup using thermomechanical finite element code ASPECT v2.0.0‐pre (Advanced Solver for Problems in the Earth's ConvecTion, Bangerth et al., 2018; Glerum et al., 2018; Heister et al., 2017; Kronbichler et al., 2012; Rose et al., 2017) to model extension of the MER. Our model is based on previous ASPECT setups aimed at modeling continental rift dynamics (Corti et al., 2019; Glerum et al., 2020; Naliboff et al., 2020). We solve the incompressible flow equations for conservation of momentum (Equation ), mass (Equation ), and energy (Equation ) assuming an infinite Prandtl number:

- \nabla \cdot false(2 η \overset{ε}{true} false(bold-italicu false) false) + \nabla italicP = ρ boldg,

\nabla \cdot bold-italicu = 0,

\overset{ρ}{true} {italicC}_{p} ((), \frac{\partial italicT}{\partial t} + bold-italicu \cdot \nabla italicT) - \nabla \cdot false(κ + ν_{h} false(italicT false) false) \nabla italicT = \overset{ρ}{true} H + 2 η ((), \overset{ε}{true} false(boldu false)) : ((), \overset{ε}{true} false(boldu false)) + α T ((), boldu \cdot \nabla P),

where η is viscosity,

\overset{ε}{true}

is strain rate tensor, u is velocity vector, P is pressure, ρ is density,

\overset{ρ}{true}

is adiabatic reference density, g is gravitational acceleration, κ is thermal diffusivity, ν h is artificial diffusivity, C p is specific heat capacity, and H is heat production.…”

Section: Numerical Modelmentioning

confidence: 99%

Mechanism for Deep Crustal Seismicity: Insight From Modeling of Deformation Processes at the Main Ethiopian Rift

Muluneh

Brune

Illsley‐Kemp

et al. 2020

Geochem Geophys Geosyst

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We combine numerical modeling of lithospheric extension with analysis of seismic moment release and earthquake b‐value in order to elucidate the mechanism for deep crustal seismicity and seismic swarms in the Main Ethiopian Rift (MER). We run 2‐D numerical simulations of lithospheric deformation calibrated by appropriate rheology and extensional history of the MER to simulate migration of deformation from mid‐Miocene border faults to ∼30 km wide zone of Pliocene to recent rift floor faults. While currently the highest strain rate is localized in a narrow zone within the rift axis, brittle strain has been accumulated in a wide region of the rift. The magnitude of deviatoric stress shows strong variation with depth. The uppermost crust deforms with maximum stress of 80 MPa, at 8–14 km depth stress sharply decreases to 10 MPa and then increases to a maximum of 160 MPa at ∼18 km depth. These two peaks at which the crust deforms with maximum stress of 80 MPa or above correspond to peaks in the seismic moment release. Correspondingly, the drop in stress at 8–14 km correlates to a low in seismic moment release. At this depth range, the crust is weaker and deformation is mainly accommodated in a ductile manner. We therefore see a good correlation between depths at which the crust is strong and elevated seismic deformation, while regions where the crust is weaker deform more aseismically. Overall, the bimodal depth distribution of seismic moment release is best explained by the rheology of the deforming crust.

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Victoria continental microplate dynamics controlled by the lithospheric strength distribution of the East African Rift

Cited by 51 publications

References 104 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

Mechanism for Deep Crustal Seismicity: Insight From Modeling of Deformation Processes at the Main Ethiopian Rift

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