Evidence of phase nucleation during olivine diffusion creep: A new perspective for mantle strain localisation

Précigout, Jacques; Stünitz, Holger

doi:10.1016/j.epsl.2016.09.029

Cited by 47 publications

(65 citation statements)

References 49 publications

(74 reference statements)

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“…In either case, cavitation should be considered as a mechanism that is capable of evolving the Zener parameter and hence the rheology of a domain from GSI to GSS. Our model ties in with more recent experimental observations by Précigout and Stünitz (2016), who also identify creep cavitation as a means of producing domains that deform by GSS creep. In contrast to our results, Précigout and Stünitz (2016) discuss the deformation of clinopyroxene embedded in an olivine matrix in which phase mixing occurs in clinopyroxene tails.…”

Section: The Role Of Creep Cavities In the Activation Of Gss Creepmentioning

confidence: 73%

“…Synkinematic creep cavitation by VGBS is not a new idea in geology: several microstructural (Behrmann and Mainprice, 1987;Herwegh and Jenni, 2001;Závada et al, 2007;Fusseis et al, 2009;Kilian et al, 2011;Menegon et al, 2015) and experimental works (Ree, 1994;Dimanov et al, 2007;Rybacki et al, 2008;Précigout and Stünitz, 2016) invoke the process. Experimental work by both Dimanov et al (2007) and Rybacki et al (2008) show that pores generated during deformation by VGBS have a complex, angular and elongated shape.…”

Section: A Model For Synkinematic Creep Cavitation By Different Mechamentioning

confidence: 99%

“…This process is interpreted to be initiated by micro-cracking. Précigout and Stünitz (2016) advocate a model in which the nucleation rate of secondary phases is high. New phases are precipitated simultaneously with micro-cracking and each new cavitation site becomes filled with new phases, which suppresses the development of a CPO.…”

Section: The Role Of Creep Cavities In the Activation Of Gss Creepmentioning

confidence: 99%

“…Many of the geological works cited interpret creep cavities as the product of VGBS that form to accommodate strain incompatibilities (Behrmann and Mainprice, 1987;Ree, 1994;Herwegh and Jenni, 2001;Dimanov et al, 2007;Závada et al, 2007;Rybacki et al, 2008;Fusseis et al, 2009;Kilian et al, 2011;Menegon et al, 2015;Précigout and Stünitz, 2016). In the VGBSbased model of Fusseis et al (2009), cavitation at one grain triple junction is balanced by cavity closure at other grain triple junctions.…”

Section: Introductionmentioning

confidence: 99%

“…To date, geological research has identified evidence for creep cavitation in natural ultramylonites from the middle crust (Behrmann and Mainprice, 1987;Mancktelow et al, 1998;Herwegh and Jenni, 2001;Fusseis et al, 2009;Kilian et al, 2011;Rogowitz et al, 2016), the lower crust (Zá-vada et al, 2007;Menegon et al, 2015) and in mantle rocks (Rovetta et al, 1986;Précigout et al, 2017). Experimental work has shown that octachloropropane, quartzite, diabase, feldspar aggregates, anorthite-diopside aggregates, olivineclinopyroxene aggregates and calcite-muscovite aggregates can develop creep cavities (Caristan, 1982;Hirth and Tullis, 1989;Ree, 1994;Dimanov et al, 2007;Rybacki et al, 2008;Delle Piane et al, 2009;Précigout and Stünitz, 2016). This dataset is small but diverse and suggests that creep cavities can occur in many types of deforming rocks across varying pressure, temperature and rate conditions.…”

Section: Introductionmentioning

confidence: 99%

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Hierarchical creep cavity formation in an ultramylonite and implications for phase mixing

et al. 2017

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Abstract. Establishing models for the formation of wellmixed polyphase domains in ultramylonites is difficult because the effects of large strains and thermo-hydro-chemomechanical feedbacks can obscure the transient phenomena that may be responsible for domain production. We use scanning electron microscopy and nanotomography to offer critical insights into how the microstructure of a highly deformed quartzo-feldspathic ultramylonite evolved. The dispersal of monomineralic quartz domains in the ultramylonite is interpreted to be the result of the emergence of synkinematic pores, called creep cavities. The cavities can be considered the product of two distinct mechanisms that formed hierarchically: Zener-Stroh cracking and viscous grain-boundary sliding. In initially thick and coherent quartz ribbons deforming by grain-size-insensitive creep, cavities were generated by the Zener-Stroh mechanism on grain boundaries aligned with the Y Z plane of finite strain. The opening of creep cavities promoted the ingress of fluids to sites of low stress. The local addition of a fluid lowered the adhesion and cohesion of grain boundaries and promoted viscous grain-boundary sliding. With the increased contribution of viscous grainboundary sliding, a second population of cavities formed to accommodate strain incompatibilities. Ultimately, the emergence of creep cavities is interpreted to be responsible for the transition of quartz domains from a grain-size-insensitive to a grain-size-sensitive rheology.

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Section: The Role Of Creep Cavities In the Activation Of Gss Creepmentioning

confidence: 73%

Section: A Model For Synkinematic Creep Cavitation By Different Mechamentioning

confidence: 99%

Section: The Role Of Creep Cavities In the Activation Of Gss Creepmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hierarchical creep cavity formation in an ultramylonite and implications for phase mixing

et al. 2017

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Rheological Weakening of Olivine + Orthopyroxene Aggregates Due to Phase Mixing: 1. Mechanical Behavior

2017

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To understand the processes involved in rheological weakening due to phase mixing in olivine + orthopyroxene aggregates, we conducted high‐strain torsion experiments on two‐phase samples at a temperature of 1200°C and a confining pressure of 300 MPa. Samples composed of iron‐rich olivine plus 26% orthopyroxene were deformed to outer radius shear strains of up to γ ≈ 26. Values for the stress exponent, n, and grain size exponent, p, were determined based on least squares fits of the strain rate, stress, and grain size data to a power law creep equation both at smaller strains (γ ≤ 3) and at larger strains (γ ≥ 24). Microstructural observations demonstrate that with increasing shear strain, grain size decreased and mixtures of small, equant grains of olivine and pyroxene developed. The values of n and p combined with associated changes in microstructure demonstrate that our samples deformed (i) by dislocation‐accommodated grain‐boundary sliding with subgrains present at lower strains and (ii) by dislocation‐accommodated grain‐boundary sliding with subgrains absent at higher strains. The evolution of both the mechanical and the microstructural properties observed in this study provide insights into the dynamic processes associated with rheological weakening and strain localization in the plastically deforming portion of the lithosphere.

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Strain Localized Deformation Variation of a Small-Scale Ductile Shear Zone

et al. 2023

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Evidence of phase nucleation during olivine diffusion creep: A new perspective for mantle strain localisation

Cited by 47 publications

References 49 publications

Hierarchical creep cavity formation in an ultramylonite and implications for phase mixing

Hierarchical creep cavity formation in an ultramylonite and implications for phase mixing

Rheological Weakening of Olivine + Orthopyroxene Aggregates Due to Phase Mixing: 1. Mechanical Behavior

Strain Localized Deformation Variation of a Small-Scale Ductile Shear Zone

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