Influence of melt on the creep behavior of olivine–basalt aggregates under hydrous conditions

Mei, Shenghua; Bai, Wangfeng; Hiraga, Takehiko; Kohlstedt, D. L.

doi:10.1016/s0012-821x(02)00745-8

Cited by 238 publications

(203 citation statements)

References 33 publications

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“…The viscosity and its temperature dependence in the solid state [34], and liquid state [35] are taken from ab initio studies. Melt fraction is assumed to vary linearly with temperature between solidus and liquidus, and the dependence of viscosity on melt fraction is taken from experiment [36,37]. The isentropic temperature (2400 K) is computed with HeFESTo assuming a potential temperature of 1600 K [38]; the solidus (3950 K) and liquidus (4950 K) temperatures are from an experimental study [39].…”

Section: −2β Pmentioning

confidence: 99%

Melting in super-earths

Stixrude

2014

Phil. Trans. R. Soc. A.

104

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We examine the possible extent of melting in rockiron super-earths, focusing on those in the habitable zone. We consider the energetics of accretion and core formation, the timescale of cooling and its dependence on viscosity and partial melting, thermal regulation via the temperature dependence of viscosity, and the melting curves of rock and iron components at the ultra-high pressures characteristic of superearths. We find that the efficiency of kinetic energy deposition during accretion increases with planetary mass; considering the likely role of giant impacts and core formation, we find that super-earths probably complete their accretionary phase in an entirely molten state. Considerations of thermal regulation lead us to propose model temperature profiles of super-earths that are controlled by silicate melting. We estimate melting curves of iron and rock components up to the extreme pressures characteristic of superearth interiors based on existing experimental and ab initio results and scaling laws. We construct superearth thermal models by solving the equations of mass conservation and hydrostatic equilibrium, together with equations of state of rock and iron components. We set the potential temperature at the core-mantle boundary and at the surface to the local silicate melting temperature. We find that ancient (∼4 Gyr) super-earths may be partially molten at the top and bottom of their mantles, and that mantle convection is sufficiently vigorous to sustain dynamo action over the whole range of super-earth masses.

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Section: −2β Pmentioning

confidence: 99%

Melting in super-earths

Stixrude

2014

Phil. Trans. R. Soc. A.

104

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“…This empirical fit has been extensively used and generally provides the best-fit to laboratory data [e.g. Hirth and Kohlstedt, 1995a;Kohlstedt, 2002;Mei, et al, 2002;Scott and Kohlstedt, 2006]. At small melt fractions the CK, HK-diffusion and HK-dislocation models approach the exponential relationship given by equation (2.37).…”

Section: B1 Influence Of Melt On Strengthmentioning

confidence: 99%

“…These experiments were followed by systematic studies investigating the influence of melt on the deformation of dry olivine [Hirth and Kohlstedt, 1995a;, olivine at hydrous condition [Mei, et al, 2002], and olivine aggregates in simple shear [Zimmerman, et al, 1999;Holtzman, et al, 2003a;Holtzman, et al, 2003b]. In all cases, the presence of melt decreased the strength of the aggregates.…”

Section: Introductionmentioning

confidence: 99%

“…Samples have sometimes been enclosed by alumina discs [e.g., Hirth and Kohlstedt, 1995a; or within metal capsules [Mei, et al, 2002]. In these configurations, often referred to as undrained deformation experiments, melt pressures may be as large as the mean stress if the sample is weak, melt is in isolated pores, or the melt viscosity is high.…”

Section: Introductionmentioning

confidence: 99%

“…Shear viscosity of partially molten aggregates is constrained by undrained deformation experiments [e.g., Hirth and Kohlstedt, 1995a;Mei, et al, 2002;Scott and Kohlstedt, 2006]. Renner et al, [2003] measured bulk viscosity and inferred sample permeability in hydrostatically compacting olivine aggregates containing various melt phases using a high-pressure carbon bead reservoir as a sink for melt.…”

Section: Introductionmentioning

confidence: 99%

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Experimental and seismological constraints on the rheology, evolution, and alteration of the lithosphere at oceanic spreading centers

deMartin¹

2007

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Oceanic spreading centers are sites of magmatic, tectonic, and hydrothermal processes. In this thesis I present experimental and seismological constraints on the evolution of these complex regions of focused crustal accretion and extension. Experimental results from drained, triaxial deformation experiments on partially molten olivine reveal that melt extraction rates are linearly dependent on effective mean stress when the effective mean stress is low and non-linearly dependent on effective mean stress when it is high. Microearthquakes recorded above an inferred magma reservoir along the TAG segment of the Mid-Atlantic Ridge delineate for the first time the arcuate, subsurface structure of a long-lived, active detachment fault. This fault penetrates the entire oceanic crust and forms the high-permeability pathway necessary to sustain long-lived, high-temperature hydrothermal venting in this region. Long-lived detachment faulting exhumes lower crustal and mantle rocks. Residual stresses generated by thermal expansion anisotropy and mismatch in the uplifting, cooling rock trigger grain boundary microfractures if stress intensities at the tips of naturally occurring flaws exceed a critical stress intensity factor. Experimental results coupled with geomechanical models indicate that pervasive grain boundary cracking occurs in mantle peridotite when it is uplifted to within 4 km of the seafloor. Whereas faults provide the high-permeability pathways necessary to sustain high-temperature fluid circulation, grain boundary cracks form the interconnected network required for pervasive alteration of the oceanic lithosphere. This thesis provides fundamental constraints on the rheology, evolution, and alteration of the lithosphere at oceanic spreading centers.

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Compaction around a rigid, circular inclusion in partially molten rock

et al. 2014

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Conservation laws that describe the behavior of partially molten mantle rock have been established for several decades, but the associated rheology remains poorly understood. Constraints on the rheology may be obtained from recently published experiments involving deformation of partially molten rock around a rigid, spherical inclusion. These experiments give rise to patterns of melt segregation that exhibit the competing effects of pressure shadows and melt‐rich bands. Such patterns provide an opportunity to infer rheological parameters through comparison with models based on the conservation laws and constitutive relations that hypothetically govern the system. To this end, we have developed software tools to simulate finite strain, two‐phase flow around a circular inclusion in a configuration that mirrors the experiments. Simulations indicate that the evolution of porosity is predominantly controlled by the porosity‐weakening exponent of the shear viscosity and the poorly known bulk viscosity. In two‐dimensional simulations presented here, we find that the balance of pressure shadows and melt‐rich bands observed in experiments only occurs for bulk‐to‐shear viscosity ratio of less than about five. However, the evolution of porosity in simulations with such low bulk viscosity exceeds physical bounds at unrealistically small strain due to the unchecked, exponential growth of the porosity variations. Processes that limit or balance porosity localization should be incorporated in the formulation of the model to produce results that are consistent with the porosity evolution in experiments.

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Influence of melt on the creep behavior of olivine–basalt aggregates under hydrous conditions

Cited by 238 publications

References 33 publications

Melting in super-earths

Melting in super-earths

Experimental and seismological constraints on the rheology, evolution, and alteration of the lithosphere at oceanic spreading centers

Compaction around a rigid, circular inclusion in partially molten rock

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