Experimental investigation of the creep behavior of garnet at high temperatures and pressures

Mei, Shenghua; Suzuki, Ayako; Kohlstedt, D. L.; Xu, Lili

doi:10.1007/s12583-010-0127-8

Cited by 15 publications

(5 citation statements)

References 32 publications

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“…For garnet, we used the flow law from Ji and Martignole () as it appears also the most appropriate for our study. The number of experimental data for garnet is indeed limited and/or most of the time dedicated to higher‐pressure‐temperature values (e.g., Katayama & Karato, ; Li et al, ; Mei et al, ). Moreover, dislocation creep in garnet is never activated in the P‐T conditions of our models.…”

Section: Discussionmentioning

confidence: 99%

Brittle/Ductile Deformation of Eclogites: Insights From Numerical Models

Yamato

Duretz

Angiboust

2019

Geochem Geophys Geosyst

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How rocks deform at depth during lithospheric convergence and what are the magnitudes of stresses they experience during burial/exhumation processes constitute fundamental questions for refining our vision of short‐term (i.e., seismicity) and long‐term tectonic processes in the Earth's lithosphere. Field evidence showing the coexistence of both brittle and ductile deformation at high pressure‐low temperature (HP‐LT) conditions particularly fuels this questioning. We here present 2D numerical models of eclogitic rock deformation by simple shear performed at centimeter scale. To approximate the eclogite paragenesis, we considered the deformed medium as composed of two mineral phases: omphacite and garnet. We run a series of models at 2.0 GPa and 550 °C for different background strain rates (from 10−14 s−1 to 10−8 s−1) and for different garnet proportions (from 0% to 55%). Results show that whole rock fracturing can occur under HP‐LT conditions for strain rates larger than ~10−10 s−1. This suggests that observation of brittle features in eclogites does not necessarily mean that they underwent extreme strain rate. Care should therefore be taken when linking failure of eclogitic rocks to seismic deformation. We also explore the ranges of parameters where garnet and omphacite are deforming with a different deformation style (i.e., frictional vs viscous) and discuss our results in the light of naturally deformed eclogitic samples. This study illustrates that effective stresses sustained by rocks can be high at these P‐T conditions. They reach up to ~1 GPa for an entirely fractured eclogite and up to ~500 MPa for rocks that contain fractured garnet.

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Section: Discussionmentioning

confidence: 99%

Brittle/Ductile Deformation of Eclogites: Insights From Numerical Models

Yamato

Duretz

Angiboust

2019

Geochem Geophys Geosyst

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“…In addition to fluid‐mediated processes, non‐hydrostatic stress at high metamorphic grades can lead to crystal plastic deformation. However, studies have shown that the minerals we consider (garnet, omphacite, and plagioclase) are exceptionally strong, especially when dry (e.g., Bystricky & Mackwell, 2001; Dimanov et al., 1999; Karato et al., 1995; Li et al., 2006; Mei et al., 2010; Rybacki & Dresen, 2004; Wang & Ji, 1999; Zhang & Green, 2007). Consequently, these minerals are likely able to sustain non‐hydrostatic stresses at high metamorphic temperatures (e.g., 500°C–800°C) with limited deformation.…”

Section: Discussionmentioning

confidence: 99%

Quantifying the Effects of Non‐Hydrostatic Stress on Multi‐Component Minerals

2022

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Mineral compositions are used to infer pressures, temperatures, and timescales of geological processes. The thermodynamic techniques underlying these inferences assume a uniform, constant pressure. Nonetheless, convergent margins generate significant non‐hydrostatic (unequal) stresses, violating the uniform pressure assumption and creating uncertainty. Materials scientists F. Larché and J. Cahn derived an equation suitable for non‐hydrostatically stressed geologic environments that links stress and equilibrium composition in elastic, multi‐component crystals. However, previous works have shown that for binary solid solutions with ideal mixing behavior, hundreds of MPa to GPa‐level stresses are required to shift mineral compositions by a few hundredths of a mole fraction, limiting the equation's applicability. Here, we apply Larché and Cahn's equation to garnet, clinopyroxene, and plagioclase solid solutions, incorporating for the first time non‐ideal mixing behavior and more than two endmembers. We show that non‐ideal mixing increases predicted stress‐induced composition changes by up to an order of magnitude. Further, incorporating additional solid solution endmembers changes the predicted stress‐induced composition shifts of the other endmembers being considered. Finally, we demonstrate that Larché and Cahn's approach yields positive entropy production, a requirement for any real process to occur. Our findings reveal that stresses between tens and a few hundred MPa can shift mineral compositions by several hundredths of a mole fraction. Consequently, mineral compositions could plausibly be used to infer stress states. We suggest that stress‐composition effects could develop via intracrystalline diffusion in any high‐grade metamorphic setting, but are most likely in hot, dry, and strong rocks such as lower crustal granulites.

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“…The mafic lower crust initially present in the orogen at the centre of the model and within the mantle transition zone is assumed to follow an eclogite power-law 52 at pressures less than 17.5 GPa . At higher pressures, a garnetite 53 flow law is assumed.…”

Section: Methodsmentioning

confidence: 99%

LIP formation and protracted lower mantle upwelling induced by rifting and delamination

Petersen

Schiffer

Nagel

2018

Sci Rep

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Large Igneous Provinces (LIPs) are commonly attributed to mantle plumes, hot upwellings from the deep lower mantle, apparently unrelated to plate motions. However, LIPs often form in association with rifting and breakup. Using numerical modelling, we introduce a novel idea that explains plume-like mantle upwelling by plate tectonic processes. Our model indicates that rifting-induced delamination of orogenic lithosphere can perturb the thermochemical mantle stratification and induce lower mantle upwelling which causes syn-rift LIP formation followed by protracted and enhanced mid ocean ridge basalt (MORB) generation. Our model provides an explanation for the geographical correlation between the Caledonian suture, the North Atlantic Igneous Province (NAIP) and present-day Icelandic magmatism.

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Experimental investigation of the creep behavior of garnet at high temperatures and pressures

Cited by 15 publications

References 32 publications

Brittle/Ductile Deformation of Eclogites: Insights From Numerical Models

Brittle/Ductile Deformation of Eclogites: Insights From Numerical Models

Quantifying the Effects of Non‐Hydrostatic Stress on Multi‐Component Minerals

LIP formation and protracted lower mantle upwelling induced by rifting and delamination

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