The participation of ilmenite-bearing cumulates in lunar mantle overturn

Zhao, Yue; Vries, J. de; Berg, A. P. van den; Jacobs, Michael; Westrenen, W. van

doi:10.1016/j.epsl.2019.01.022

Cited by 74 publications

(72 citation statements)

References 44 publications

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“…Parmentier et al () presented a numerical model illustrating this process. Our results in the supporting information suggest a >150‐km IBC thickness, which is also consistent with estimation from recent study (Zhao et al, ). Thus, we consider IBC layer thickness up to 150 km, larger than the maximum of 50 km predicted by mass balance alone.…”

Section: Model Formulationsupporting

confidence: 93%

“…In addition to its density and thickness, the viscosity contrast between the IBC layer and the underlying mantle plays a key role in determining the dynamical behavior of an IBC layer (Elkins-Tanton et al, 2002;Parmentier et al, 2002;Scheinberg et al, 2014). Previous modeling studies either regarded the IBC viscosity to be the same as that of peridotite or arbitrarily assigned a range of values for parameter explorations (e.g., Elkins-Tanton et al, 2002;Parmentier et al, 2002;Yu et al, 2019;Zhao et al, 2019). Here we explore a range of IBC viscosities constrained by the results of a recent experimental study which, for the first time, measured the viscosity of ilmenite and extrapolated the measurement to the viscosity of harzburgitemixed IBC (Figure 2; Dygert et al, 2016).…”

Section: Physical and Chemical Properties Of The Ibc Layermentioning

confidence: 99%

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Lunar Cumulate Mantle Overturn: A Model Constrained by Ilmenite Rheology

Zhang

Liang

et al. 2019

JGR Planets

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Lunar cumulate mantle overturn has been proposed to explain the abundances of TiO2 and heat‐producing elements (U, Th, and K) in the source region of lunar basalts. Ilmenite‐bearing cumulates (IBCs) that were formed near the end of lunar magma ocean solidification are the driving force for overturn. IBCs are enriched with dense TiO2 and FeO contents and have lower viscosity and solidus than those of the underlying lunar cumulate mantle. We investigate the effects of temperature‐ and ilmenite‐dependent mantle rheology on the dynamic process of lunar cumulate mantle overturn and conditions for long‐wavelength downwellings of an IBC layer in a 3‐D spherical geometry. Our results show that the ilmenite‐induced rheological weakening is necessary to decouple the IBC layer from the top stagnant lid and facilitate overturn. Models with IBC viscosity derived from the experimental scaling can only produce short‐wavelength downwellings (spherical harmonic degree >3) and show an overturn timescale more than 100 Ma. A viscosity of the IBC layer at least 10−4 lower than that of the ambient mantle can produce the long‐wavelength (spherical harmonic degree ≤3) downwellings in ~10 Ma and even a hemispheric downwelling. Such low IBC viscosity requires additional weakening mechanisms, such as remelting or/and water enrichment. During the overturn, the cold downwellings displace upward the materials from hot lower mantle and produce partial melting in upper mantle, which may serve as a viable mechanism for early lunar magmatisms. The settling of cold downwellings on the core‐mantle boundary stimulates a transient high heat flux, which may contribute to generating an early lunar dynamo event.

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Section: Model Formulationsupporting

confidence: 93%

Section: Physical and Chemical Properties Of The Ibc Layermentioning

confidence: 99%

Lunar Cumulate Mantle Overturn: A Model Constrained by Ilmenite Rheology

Zhang

Liang

et al. 2019

JGR Planets

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“…A combination of recent analyses of Apollo-era samples (e.g., Borg et al, 2011;Saal et al, 2013;Tartèse and Anand, 2013;Hauri et al, 2015), reassessment of lunar seismic data (Garcia et al, 2011;Weber et al, 2011), orbital measurements from recent lunar missions (e.g., Pieters et al, 2009;Yamamoto et al, 2010;Wu et al, 2012;Wieczorek et al, 2013), and results from advanced experimental and computational studies (e.g., de Vries et al, 2010;Elardo et al, 2011;Jutzi and Asphaug, 2011;Cuk and Stewart, 2012;van Kan Parker et al, 2012;Lin et al, 2017a,b;Charlier et al, 2018;Rapp and Draper, 2018;Zhao et al, 2019) are revolutionizing our view of the formation and general evolution of the surface and interior of the Moon. Detailed models of key aspects of lunar magmatic evolution are still hampered by a lack of quantitative constraints on the physical properties of lunar magma at high pressures (P) and temperatures (T).…”

Section: Introductionmentioning

confidence: 99%

In situ Viscometry of Primitive Lunar Magmas at High Pressure and High Temperature

et al. 2019

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Understanding the dynamics of the magmatic evolution of the interior of the Moon requires accurate knowledge of the viscosity (η) of lunar magmas at high pressure (P) and high temperature (T) conditions. Although the viscosities of terrestrial magmas are relatively well-documented, and their relation to magma composition well-studied, the viscosities of lunar titano-silicate melts are not well-known. Here, we present an experimentally measured viscosity dataset for three end member compositions, characterized by a wide range of titanium contents, at lunar-relevant pressuretemperature range of ∼1.1-2.4 GPa and 1830-2090 K. In situ viscometry using the falling sphere technique shows that the viscosity of lunar melts varies between ∼0.13 and 0.87 Pa-s depending on temperature, pressure and composition. Viscosity decreases with increasing temperature with activation energies for viscous flow of E a = 201 kJ/mol and E a = 106 kJ/mol for low-titanium (Ti) and high-Ti melts, respectively. Pressure is found to mildly increase the viscosity of these intermediate polymerized melts by a factor of ∼1.5 between 1.1 and 2.4 GPa. Viscosities of low-Ti and high-Ti magmas at their respective melting temperatures are very close. However at identical P-T conditions (∼1.3 GPa, ∼1840 K) low-Ti magmas are about a factor of three more viscous than high-Ti magmas, reflecting structural effects of Si and Ti on melt viscosity. Measured viscosities differ significantly from empirical models based on measurements of the viscosity of terrestrial basalts, with largest deviations observed for the most Tirich and Si-poor composition. Viscosity coefficients for these primitive lunar melts are found to be lower than those of common terrestrial basalts, giving them a high mobility throughout the lunar mantle and onto the surface of the Moon despite their Fe and Ti-rich compositions.

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“…SEPRAN is a general purpose finite element toolkit applied in engineering problems as well as in development of 2-D and 3-D numerical models in geodynamics and planetary science (Chertova et al, 2012(Chertova et al, , 2014Čížková et al, 2012;van den Berg et al, 2015Zhao et al, 2019). The model contains a lithospheric slab subducting under an overriding plate as shown in Fig.…”

Section: Using the Gwb With Sepranmentioning

confidence: 99%

“…For example, 3-D initial models of a geometrically simplified nature are often constructed for modeling of generic subduction evolution using plate boundaries and lithosphere domains that are parallel to the sides of the (rectangular) model domain (e.g., Yamato et al, 2009;Stegman et al, 2010;Brune and Autin, 2013;Schellart and Moresi, 2013;Duretz et al, 2014;Holt et al, 2015;Leng and Gurnis, 2015;Naliboff and Buiter, 2015;Kiraly et al, 2016;Schellart, 2017). When numerically simulating (regions of) the Earth, geometrically more complex initial models are required, e.g., involving the starting plate tectonic layout, initial trench geometry and slab shape for use in either instantaneous dynamics modeling or as an initial model for modeling of subduction evolution (e.g., Alisic et al, 2012;Liu and Stegman, 2011;Billen, 2010, 2012;Chertova et al, 2014;Billen and Arredondo, 2018;Zhou et al, 2018). Such initial model setups cannot be easily created, adapted or shared with the community, nor easily transferred to another code.…”

Section: Introductionmentioning

confidence: 99%

The Geodynamic World Builder: a solution for complex initial conditions in numerical modeling

et al. 2019

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Abstract. The Geodynamic World Builder is an open-source code library intended to set up initial conditions for computational geodynamic models in both Cartesian and spherical geometries. The inputs for the JavaScript Object Notation (JSON)-style parameter file are not mathematical but rather a structured nested list describing tectonic features, e.g., a continental, an oceanic or a subducting plate. Each of these tectonic features can be assigned a specific temperature profile (e.g., plate model) or composition label (e.g., uniform). For each point in space, the Geodynamic World Builder can return the composition and/or temperature. It is written in C++ but can be used in almost any language through its C and Fortran wrappers. Various examples of 2-D and 3-D subduction settings are presented. The Geodynamic World Builder comes with an extensive online user manual.

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The participation of ilmenite-bearing cumulates in lunar mantle overturn

Cited by 74 publications

References 44 publications

Lunar Cumulate Mantle Overturn: A Model Constrained by Ilmenite Rheology

Lunar Cumulate Mantle Overturn: A Model Constrained by Ilmenite Rheology

In situ Viscometry of Primitive Lunar Magmas at High Pressure and High Temperature

The Geodynamic World Builder: a solution for complex initial conditions in numerical modeling

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