Neutral buoyancy of titanium-rich melts in the deep lunar interior

Parker, M. van Kan; Sanloup, C.; Sator, Nicolas; Guillot, B.; Tronche, E. J.; Perrillat, Jean-Philippe; Mézouar, M.; Rai, Nachiketa; Westrenen, W. van

doi:10.1038/ngeo1402

Cited by 67 publications

(47 citation statements)

References 23 publications

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“…These samples represent the most primitive lunar magmas to have been collected to date [e.g., Delano, 1986]. Analyses showed that only the most TiO 2 -rich primitive lunar melts, corresponding to Apollo 14 black glass (∼16 wt % TiO 2 ), would be neutrally buoyant with respect to the lunar mantle [e.g., Delano, 1990;Circone and Agee, 1996;Smith and Agee, 1997;Sakamaki et al, 2010;van Kan Parker et al, 2011, 2012. This observation has fueled speculation that the source of pristine mare glasses, considered to be the best candidates for lunar primary magmas [Delano, 1986], could be related to the melt-bearing layer.…”

Section: Introductionmentioning

confidence: 99%

“…Toward the end of magma-ocean crystallization ilmenite-bearing cumulates would have formed a thin layer at the base of the crust and, owing to their high density relative to surrounding mantle, would become gravitationally unstable (cumulate pile overturn) and sink [e.g., Hess and Parmentier, 1995;Shearer and Papike, 1999;Elkins-Tanton et al, 2002Shearer et al, 2006]. Moreover, as ilmenite cumulates likely also integrated heat-producing elements (U, Th, and K), they might be responsible for having initiated melting at depth [e.g., Shearer et al, 1991] producing dynamically stable TiO 2 -rich melts in the deep lunar interior [e.g., Delano, 1990;Sakamaki et al, 2010;van Kan Parker et al, 2012], providing an explanation for the presence of deep-seated partial melt [e.g., Nakamura et al, 1973;Williams et al, 2001;Weber et al, 2011].…”

Section: Introductionmentioning

confidence: 99%

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Geophysical evidence for melt in the deep lunar interior and implications for lunar evolution

Khan

Connolly

Pommier

et al. 2014

J. Geophys. Res. Planets

116

176

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Analysis of lunar laser ranging and seismic data has yielded evidence that has been interpreted to indicate a molten zone in the lowermost mantle overlying a fluid core. Such a zone provides strong constraints on models of lunar thermal evolution. Here we determine thermochemical and physical structure of the deep Moon by inverting lunar geophysical data (mean mass and moment of inertia, tidal Love number, and electromagnetic sounding data) in combination with phase-equilibrium computations. Specifically, we assess whether a molten layer is required by the geophysical data. The main conclusion drawn from this study is that a region with high dissipation located deep within the Moon is required to explain the geophysical data. This region is located within the mantle where the solidus is crossed at a depth of ∼1200 km (≥1600• C). Inverted compositions for the partially molten layer (150-200 km thick) are enriched in FeO and TiO 2 relative to the surrounding mantle. The melt phase is neutrally buoyant at pressures of ∼4.5-4.6 GPa but contains less TiO 2 (<15 wt %) than the Ti-rich (∼16 wt %) melts that produced a set of high-density primitive lunar magmas (density of 3.4 g/cm 3 ). Melt densities computed here range from 3.25 to 3.45 g/cm 3 bracketing the density of lunar magmas with moderate-to-high TiO 2 contents. Our results are consistent with a model of lunar evolution in which the cumulate pile formed from crystallization of the magma ocean as it overturned, trapping heat-producing elements in the lower mantle.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Geophysical evidence for melt in the deep lunar interior and implications for lunar evolution

Khan

Connolly

Pommier

et al. 2014

J. Geophys. Res. Planets

116

176

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“…S1). The temperature imposes further constraints: if partial melting is present at the bottom of the mantle (10,32), temperatures at the core−mantle boundary (CMB) must exceed 1,650 K. The temperature at the inner core/outer core boundary (ICB) may be only a few tens of degrees higher than that at CMB, if we assume a nonconvective subadiabatic liquid, an assumption compatible with the absence of an active lunar dynamo (33). For temperatures at the ICB of at least 1,700 K, the amount of sulfur in the liquid phase could be brought down to 20 at.%, and even less for higher temperatures (Fig.…”

Section: Significancementioning

confidence: 99%

Toward a mineral physics reference model for the Moon’s core

Antonangeli

Morard

Schmerr

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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The physical properties of iron (Fe) at high pressure and high temperature are crucial for understanding the chemical composition, evolution, and dynamics of planetary interiors. Indeed, the inner structures of the telluric planets all share a similar layered nature: a central metallic core composed mostly of iron, surrounded by a silicate mantle, and a thin, chemically differentiated crust. To date, most studies of iron have focused on the hexagonal closed packed (hcp, or e) phase, as e-Fe is likely stable across the pressure and temperature conditions of Earth's core. However, at the more moderate pressures characteristic of the cores of smaller planetary bodies, such as the Moon, Mercury, or Mars, iron takes on a facecentered cubic (fcc, or γ) structure. Here we present compressional and shear wave sound velocity and density measurements of γ-Fe at high pressures and high temperatures, which are needed to develop accurate seismic models of planetary interiors. Our results indicate that the seismic velocities proposed for the Moon's inner core by a recent reanalysis of Apollo seismic data are well below those of γ-Fe. Our dataset thus provides strong constraints to seismic models of the lunar core and cores of small telluric planets. This allows us to propose a direct compositional and velocity model for the Moon's core.iron | high pressure | high temperature | Moon | telluric planetary cores E ven though the telluric planets and satellites have metallic cores composed mainly of iron, differences in bulk masses imply different pressure (P) and temperature (T) conditions at the center of these bodies. This, in turn, reflects on the solid versus liquid nature of the core and on the stable crystalline structure of the solid phase. The hexagonal closed-packed (hcp, or e) phase is likely the stable Fe phase across the pressure and temperature conditions of Earth's core (1). At the moderate P−T characteristic of the cores of relatively small planets, such as Mercury (P between ∼8 GPa and ∼40 GPa, T between ∼1,700 K and ∼2,200 K) (2) or Mars (P between ∼24 GPa and ∼42 GPa, T between ∼2,000 K and 2,600 K) (3, 4), or satellites, including the Moon (P∼5-6 GPa, T between 1,300 K and 1,900 K) (5), the expected iron stable structure is face-centered cubic (fcc, or γ) (6). For this phase, there are not extensive experimental measurements of the aggregate sound velocities as a function of pressure and temperature. Studies are limited to a single determination of the Debye velocity at 6 GPa and 920 K (7) and to an inelastic neutron scattering (INS) experiment at ambient pressure and 1,428 K (8), although a complete and consistent set of measurements of compressional and shear wave sound velocities (respectively, V P and V S ) and density (ρ) at high pressure and high temperature are essential parameters needed to develop reliable seismic models of planetary cores.The Moon is the only other telluric body besides Earth for which multiple direct seismic observations are available. These were provided by the Apollo Lunar Surface ...

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“…An advanced technique becomes popular for melt density measurements. This technique combines synchrotron X-ray absorption measurement with a large volume press and has been conducted successfully on a number of melts by several authors (Katayama et al, 1993;Sanloup et al, 2000;Sakamaki et al, 2009Sakamaki et al, , 2010aSakamaki et al, , 2010bSakamaki et al, , 2011Nishida et al, 2011;van Kan Parker et al, 2012;Sakamaki et al, 2013;Seifert et al, 2013;Malfait et al, 2014aMalfait et al, , 2014b. This well-established technique allows us to measure density of liquid under desired pressure and temperature conditions with much improved precision and accuracy.…”

Section: Introductionmentioning

confidence: 99%

Density of jadeite melts under high pressure and high temperature conditions

Sakamaki

2017

Journal of Mineralogical and Petrological Sciences

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The density of the jadeite (NaAlSi 2 O 6 ) melt has been measured up to 6.5 GPa and 2273 K using the X-ray absorption technique at beamline 13-BM-D of the Advanced Photon Source. A fit of the pressure-densitytemperature data to the high temperature Birch-Murnaghan equation of state yielded the following thermoelastic parameters: density, ρ 0 = 2.36 g/cm 3 , isothermal bulk modulus, K T0 = 21.5 ± 0.8 GPa, its pressure derivative, K 0 A = 8.9 ± 1.2, and the temperature derivative (∂K T /∂T ) P = −0.0021 ± 0.0011 GPa/K at a reference temperature T 0 = 1473 K. The densification of jadeite melt at low pressures is primarily dominated by topological changes in the structure, including a decrease in T-O-T angle and breaking and reforming of the T-O bond (T = Si 4+ , Al 3+ ). Compressibilities of jadeite, albite, diopside, phonolite and peridotite melts display a systematic trend: the K 0 -K 0 A plot of these silicate melts exhibits an inverse linear relation.

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Neutral buoyancy of titanium-rich melts in the deep lunar interior

Cited by 67 publications

References 23 publications

Geophysical evidence for melt in the deep lunar interior and implications for lunar evolution

Geophysical evidence for melt in the deep lunar interior and implications for lunar evolution

Toward a mineral physics reference model for the Moon’s core

Density of jadeite melts under high pressure and high temperature conditions

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