Collapse of passive margins by lithospheric damage and plunging grain size

Mulyukova, Elvira; Bercovici, David

doi:10.1016/j.epsl.2017.12.022

Cited by 33 publications

(24 citation statements)

References 43 publications

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“…Thus, DRX has long been considered an essential process for the accumulation of large plastic strains in the Earth's crust and mantle (Etheridge & Wilkie, 1979;Montési & Hirth, 2003;Platt & Behr, 2011;Poirier, 1980;Tullis & Yund, 1985;White et al, 1980). More recently, it has also been argued that DRX and grain size evolution play a key role in other geodynamic phenomena, including mantle convection (Barr & McKinnon, 2007;Dannberg et al, 2017;Hall & Parmentier, 2003;Rozel, 2012), mantle plume dynamics (Korenaga, 2005), intermediate-depth earthquake nucleation (Thielmann et al, 2015), passive margin collapse (Mulyukova & Bercovici, 2018), and plate boundary formation (e.g., Bercovici & Ricard, 2012).…”

Section: Introductionmentioning

confidence: 99%

Rates of Dynamic Recrystallization in Geologic Materials

Cross

Skemer

2019

JGR Solid Earth

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Grain size reduction via dynamic recrystallization (DRX) is intimately related to the softening of crystalline materials under an applied stress, and plays a role in numerous geodynamic processes that involve strain‐weakening feedbacks. Despite its importance, few studies have provided empirical constraints on the rates of DRX and grain size reduction. Here we examine DRX rates using the Johnson‐Mehl‐Avrami‐Kolmogorov theory for phase transformation kinetics. Our analysis uses a compilation of published and newly‐derived DRX data from experimental studies on a wide range of geologic and engineering materials. We find that DRX rates are strongly dependent on the homologous temperature at which deformation occurs, with DRX occurring over a broad range of shear strains (0.01 < γ < 200), and more rapidly with increasing homologous temperature. Moreover, the experimental data can be described by a single fit to a modified form of the Avrami equation that incorporates homologous temperature dependence, implying that, to first order, DRX rates are largely material independent. We also examine the influence of stress, deformation work rate, crystal orientation, and initial grain size on DRX rates and compare DRX data from experimental and natural conditions. Overall, we show that microstructures can evolve over long transient intervals, and provide a framework for determining DRX kinetics from empirical data, which can ultimately be incorporated into geodynamic models of grain size evolution in the Earth.

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Section: Introductionmentioning

confidence: 99%

Rates of Dynamic Recrystallization in Geologic Materials

Cross

Skemer

2019

JGR Solid Earth

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“…The combined effect of thermal stiffening, slow recovery from damage‐induced weakening, and the increasing stress from ridge push determine the time window within which the thickening oceanic plates can undergo strain localization and weakening. A weakened plate is more likely to yield to gravity and potentially lead to the collapse of passive margins, as is, for example, hypothesized for spontaneous subduction initiation (Mulyukova & Bercovici, ). At modern Earth conditions, the grain damage theory predicts that the passive margins collapse within 100 Myr or do not collapse at all (Mulyukova & Bercovici, ), which is consistent with the observation that many present‐day passive margins are older than 100 Myr (Müller et al, ).…”

Section: Applicationsmentioning

confidence: 92%

“…A weakened plate is more likely to yield to gravity and potentially lead to the collapse of passive margins, as is, for example, hypothesized for spontaneous subduction initiation (Mulyukova & Bercovici, ). At modern Earth conditions, the grain damage theory predicts that the passive margins collapse within 100 Myr or do not collapse at all (Mulyukova & Bercovici, ), which is consistent with the observation that many present‐day passive margins are older than 100 Myr (Müller et al, ). Similar analysis shows that formation of new trenches by the collapse of passive margins occurred more readily on early Earth, facilitated by the hotter mantle and a larger thermal contrast across the lithosphere (thus stronger ridge push); meanwhile, spontaneous subduction initiation with the help from grain damage is harder on Venus, due to its hotter conditions (thus faster grain growth and healing) and an arguably lower temperature drop across the lithosphere (Mulyukova & Bercovici, ).…”

Section: Applicationsmentioning

confidence: 92%

“…Due to its simplicity, relative to the full set of equations and , the pinned state limit is frequently used in geodynamic applications of grain damage theory (Bellas et al, ; Bercovici et al, , ; Mulyukova & Bercovici, , ).…”

Section: Grain Damage Physicsmentioning

confidence: 99%

“…Taking into account the polymineralic nature of rocks and the different regimes of mixing between mineral phases, the two‐phase grain damage theory predicts a hysteretic behavior of the Earth's lithosphere, wherein weak, rapidly deforming, and strongly localized plate boundaries coexist with the strong and largely undeformed plate interiors at the same stress and temperature conditions. Applications of the grain damage theory include the formation and longevity of new plate boundaries by accumulation and inheritance of damage (Bercovici & Ricard, ; ; Foley et al, ; Mulyukova & Bercovici, ), generation of strike‐slip motion (Bercovici & Ricard, ; ), evolution and rearrangement of existing plate boundaries by rapid slab detachment and rollback (Bellas et al, ; Bercovici et al, , ), and the development of microstructure in deep lithospheric shear zones (Landuyt & Bercovici, ; Mulyukova & Bercovici, , ).…”

Section: Summary and Future Directionsmentioning

confidence: 99%

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The Generation of Plate Tectonics From Grains to Global Scales: A Brief Review

Mulyukova

Bercovici

2019

Tectonics

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The physics of rock deformation in the lithosphere governs the formation of tectonic plates, which are characterized by strong, broad plate interiors, separated by weak, localized plate boundaries. The size of mineral grains in particular controls rock strength and grain reduction can lead to shear localization and weakening in the strong ductile portion of the lithosphere. Grain damage theory describes the competition between grain growth and grain size reduction as a result of deformation, and the effect of grain size evolution on the rheology of lithospheric rocks. The self-weakening feedback predicted by grain damage theory can explain the formation of mylonites, typically found in deep ductile lithospheric shear zones, which are characteristic of localized tectonic plate boundaries. The amplification of damage is most effective when minerallic phases, like olivine and pyroxene, are well mixed on the grain scale. Grain mixing theory predicts two coexisting deformation states of unmixed materials undergoing slow strain rate, and well-mixed materials with large strain rate; this is in agreement with recent laboratory experiments, and is analogous to Earth's plate-like state. A new theory for the role of dislocations in grain size evolution resolves the rapid timescale of dynamic recrystallization. In particular, a toy model for the competition between normal grain growth and dynamic recrystallization predicts oscillations in grain size with periods comparable to earthquake cycles and postseismic recovery, thus connecting plate boundary formation processes to the human timescale.

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Mantle Convection

Bercovici¹,

Mulyukova²

2020

Encyclopedia of Solid Earth Geophysics

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Collapse of passive margins by lithospheric damage and plunging grain size

Cited by 33 publications

References 43 publications

Rates of Dynamic Recrystallization in Geologic Materials

Rates of Dynamic Recrystallization in Geologic Materials

The Generation of Plate Tectonics From Grains to Global Scales: A Brief Review

Mantle Convection

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