Acceleration of continental rifting due to a thermomechanical instability

Takeshita, Toru; Yamaji, Atsushi

doi:10.1016/0040-1951(90)90024-3

Cited by 21 publications

(13 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thermomechanical finite element modeling has shown that rheology may play a critical role in the deformation of the lithosphere, particularly in the development of focused shear zones, resulting in decreasing and increasing rift velocity [Huismans and Beaumont, 2003]. Strain localization can determine the style of lithospheric deformation in an extensional regime [Frederiksen and Braun, 2001], as changes to rheology alone can drive acceleration and deceleration of rifting in the presence of a constant extensional force [Takeshita and Yamaji, 1990]. Rheologic changes related to magmatic activity may also factor into deformation by promoting thermal weakening and strain localization in the crust [Whitney et al, 2013], thus facilitating extension via a feedback mechanism between magmatism and extension during decompression and crustal thinning [Teyssier and Whitney, 2002].…”

Section: Acceleration Of Rifting In Tibetmentioning

confidence: 99%

Evidence for constriction and Pliocene acceleration of east‐west extension in the North Lunggar rift region of west central Tibet

et al. 2013

View full text Add to dashboard Cite

[1] The active north trending North Lunggar rift in west central southern Tibet exposes an extensional metamorphic core complex bounded by an east dipping low-angle normal fault. Apatite and zircon (U-Th)/He thermochronology and thermal modeling of the North Lunggar rift document a minimum timing for rift inception at >10 Ma and rapid footwall exhumation between 5 and 2 Ma. Miocene footwall cooling and exhumation rates were initially slow to moderate at <50°C Ma À1 and <1 mm a À1 , followed by increased Pliocene rates as high as >400°C Ma À1 and 4-10 mm a À1 . Footwall isotherms were significantly compressed during rapid exhumation resulting in an elevated transient geothermal gradient between 50 and 90°C km À1 . The minimum magnitude of horizontal extension for the North Lunggar rift is 8.1-12.8 km; maximum is 15-20 km, less in the south at~10 km. Mean Pliocene extension rate is 1.2-2.4 mm a À1 in the~120°direction. Results for the North Lunggar rift are similar in magnitude, rate, and orientation of slip to the kinematically linked Lamu Co dextral strike-slip fault to the north. This suggests a state of constrictional strain during Pliocene time along this stretch of the Bangong-Nujiang suture from which the Lamu Co fault emanates. The onset of extension in this region may be explained by crustal thickening and gravitational orogenic collapse, followed by accelerated rifting resulting from localized crustal stretching and increased magmatic activity, potentially driven by the position and northward extent of underthrusting Indian lithosphere.

show abstract

Section: Acceleration Of Rifting In Tibetmentioning

confidence: 99%

Evidence for constriction and Pliocene acceleration of east‐west extension in the North Lunggar rift region of west central Tibet

et al. 2013

View full text Add to dashboard Cite

show abstract

“…Models with velocity boundary conditions usually impose constant velocities at the lateral model sides, which allows to study the effect of extension rate on rift processes (e.g., Ammann et al, 2017;Armitage et al, 2018;Brune et al, 2017). A second category of models apply a constant extensional force in order to investigate how rift velocities evolve through time (Brune et al, 2012(Brune et al, , 2013Takeshita & Yamaji, 1990). All of these models, however, have the disadvantage that rift velocities have to be known a priori.…”

Section: Introductionmentioning

confidence: 99%

“…More complex setups involve temporarily varying velocities to match observations (e.g., Koptev et al, 2015;Naliboff & Buiter, 2015;Salerno et al, 2016) or spatially varying velocities mimicking basin opening around an Euler pole (Mondy et al, 2017). Another problem of rift models with force boundary conditions is that the necking instability, that is, the rift localization during thinning of the lithosphere, leads to exponentially growing rift velocities (Takeshita & Yamaji, 1990), such that the bulk extension rates eventually reach unrealistically high values unless a switch to velocity boundary conditions at a limiting velocity is implemented . A second category of models apply a constant extensional force in order to investigate how rift velocities evolve through time (Brune et al, 2012(Brune et al, , 2013Takeshita & Yamaji, 1990).…”

Section: Introductionmentioning

confidence: 99%

Breakup Without Borders: How Continents Speed Up and Slow Down During Rifting

Ulvrová

Brune

Williams

2019

Geophysical Research Letters

View full text Add to dashboard Cite

Relative plate motions during continental rifting result from the interplay of local with far‐field forces. Here we study the dynamics of rifting and breakup using large‐scale numerical simulations of mantle convection with self‐consistent evolution of plate boundaries. We show that continental separation follows a characteristic evolution with four distinctive phases: (1) an initial slow rifting phase with low divergence velocities and maximum tensional stresses, (2) a synrift speed‐up phase featuring an abrupt increase of extension rate with a simultaneous drop of tensional stress, (3) the breakup phase with inception of fast sea‐floor spreading, and (4) a deceleration phase occurring in most but not all models where extensional velocities decrease. We find that the speed‐up during rifting is compensated by subduction acceleration or subduction initiation even in distant localities. Our study illustrates new links between local rift dynamics, plate motions, and subduction kinematics during times of continental separation.

show abstract

“…To overcome limits of the CSR concept, Kusznir (1982, 1991), Kusznir & Park (1984, 1987), Takeshita & Yamaji (1990) and Hopper & Buck (1993) discussed stress distributions in continental lithosphere assuming a tectonic force that is constant with (temporal) variations of lithospheric strength and the rate of deformation,…”

Section: Constant Strain Rate and Constant Force Modelmentioning

confidence: 99%

“…However, the kinematic concept may lead to an unrealistic high stress level when applied to stable regions (see below), which limits applying it to real situations. An alternative approach keeps the tectonic force imposed on the lithospheric model constant (Kusznir 1982, 1991; Kusznir & Park 1984, 1987; Takeshita & Yamaji 1990; Hopper & Buck 1993). The constant force (CF) model overcomes the problem of unrealistically high stress level that may arise from the CSR assumption.…”

Section: Introductionmentioning

confidence: 99%

A strain-rate-dependent force model of lithospheric strength

Porth¹

2000

Geophysical Journal International

View full text Add to dashboard Cite

Summary This study investigates the rate of intraplate deformation, the vertically integrated stress magnitude and vertical distributions of tectonic stress in continental lithosphere that is subjected to horizontal tectonic force. The fundamental assumption of this study is that the magnitude of the imposed tectonic force depends on the rate of deformation. This modification of the often applied strength envelope concept accounts for resistance forces generated externally to the lithospheric section that the calculated vertical stress distribution is considered to represent. The model presented overcomes the difficulties that arose in previous constant strain rate and constant force approaches and thus proves to be physically more realistic. Results are discussed with emphasis on the effects related to the strain‐rate‐dependent force assumption and on differences from the results of both previous approaches. The strain‐rate‐dependent force model predicts that in and adjacent to a weak and fast‐deforming lithospheric plate, the integrated stress magnitude is significantly reduced due to externally derived resistance forces. Modelling results suggest that the rate of intraplate deformation in many cases is controlled by the balance of externally derived deformation‐driving and externally derived deformation‐resisting forces, but is relatively insensitive to the low internal strength of the deforming lithosphere. The integrated stress level in regions of active intraplate deformation, in contrast, is predicted to be largely controlled by the time‐independent brittle strength. The strain‐rate‐dependent force model provides a geodynamic concept that allows one to investigate intraplate stress distribution depending on tectonic force magnitude, lithospheric strength and rate of intraplate deformation.

show abstract

Acceleration of continental rifting due to a thermomechanical instability

Cited by 21 publications

References 48 publications

Evidence for constriction and Pliocene acceleration of east‐west extension in the North Lunggar rift region of west central Tibet

Evidence for constriction and Pliocene acceleration of east‐west extension in the North Lunggar rift region of west central Tibet

Breakup Without Borders: How Continents Speed Up and Slow Down During Rifting

A strain-rate-dependent force model of lithospheric strength

Contact Info

Product

Resources

About