Employing magma ocean crystallization models to constrain structure and composition of the lunar interior

Schwinger, Sabrina; Breuer, D.

doi:10.1016/j.pepi.2021.106831

Cited by 10 publications

(8 citation statements)

References 77 publications

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“…However, this scenario is still highly putative and requires further studies. On the other hand, inefficient overturn would produce Fe‐Ti‐rich domains in the shallower lunar mantle (Schwinger & Breuer, 2022; Zhao et al., 2019), forming a hybrid, heterogeneous mantle for the source of mare basalts and ultramafic glasses (Elkins Tanton et al., 2002). Subsequent impact events may have triggered melting of the hybrid, heterogeneous upper mantle, generating mare basalts asymmetrically in the nearside of the Moon (Zhang et al., 2022).…”

Section: Discussionmentioning

confidence: 99%

Experimental Evidence Supporting an Overturned Iron‐Titanium‐Rich Melt Layer in the Deep Lunar Interior

Jing

Orman

et al. 2022

Geophysical Research Letters

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Dense Fe‐Ti‐rich cumulates, formed as the last dregs of the lunar magma ocean, are thought to have driven a large‐scale overturn of the lunar mantle over 4 Ga ago. Analysis of lunar seismic data has implied that some of the overturned bodies may have reached the lunar core‐mantle boundary and remained there until the present day as a partially molten layer. However, whether such a molten layer could be stable during >4 Ga of post‐magma‐ocean lunar history and explain lunar seismic observations remains poorly constrained. Here, we report the first sound velocity measurements on a Fe‐Ti‐rich lunar melt up to conditions of the lowermost lunar mantle. Our results suggest that a partial melt layer with at least 20% overturned Fe‐Ti‐rich melt can be trapped atop the lunar core‐mantle boundary until the present day, strongly influencing the thermochemical evolution of the lunar interior.

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Section: Discussionmentioning

confidence: 99%

Experimental Evidence Supporting an Overturned Iron‐Titanium‐Rich Melt Layer in the Deep Lunar Interior

Jing

Orman

et al. 2022

Geophysical Research Letters

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“…In the initial condition, we assume that the deep mantle is more enriched in HPEs and the IBC components than the shallower mantle as earlier models of mantle differentiation by the magma ocean and subsequent mantle overturn suggest (e.g., Hess & Parmentier, 1995;Moriarty III et al, 2021;Ringwood & Kesson, 1976). Several previous studies, however, suggest that a portion of the IBC materials enriched in HPEs persist just beneath the crust even after mantle overturn (e.g., Schwinger & Breuer, 2022;Yu et al, 2019;Zhao et al, 2019). Instead of explicitly simulating these remains of HPE-enriched materials, we assume that the crust is uniformly enriched in HPEs.…”

Section: Model Descriptionmentioning

confidence: 99%

The Volcanic and Radial Expansion/Contraction History of the Moon Simulated by Numerical Models of Magmatism in the Convective Mantle

Kameyama,

Ogawa

2023

JGR Planets

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To understand the evolution of the Moon, we numerically modeled mantle convection and magmatism in a two‐dimensional polar rectangular mantle. Magmatism occurs as an upward permeable flow of magma generated by decompression melting through the convecting matrix. The mantle is assumed to be initially enriched in heat‐producing elements (HPEs) and compositionally dense ilmenite‐bearing cumulates (IBC) at its base. Here, we newly show that magma generation and migration play a crucial role in the calculated volcanic and radial expansion/contraction history. Magma is generated in the deep mantle by internal heating for the first several hundred million years. A large volume of the generated magma ascends to the surface as partially molten plumes driven by melt buoyancy; the magma generation and ascent cause a volcanic activity and radial expansion of the Moon with the peak at 3.5–4 Gyr ago. Eventually, the Moon begins to radially contract when the mantle solidifies by cooling from the surface boundary. As the mantle is cooled, the activity of partially molten plumes declines but continues for billions of years after the peak because some basal materials enriched in the dense IBC components hold HPEs. The calculated volcanic and radial expansion/contraction history is consistent with the observed history of the Moon. Our simulations suggest that a substantial fraction of the mantle was solid, and there was a basal layer enriched in HPEs and the IBC components at the beginning of the history of the Moon.

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“…The program FXMOTR from the software package SPICES was used for modeling the solidification of the first ~45% of the magma ocean until only olivine was present at the liquidus. Once orthopyroxene joins olivine on the cotectic, alphaMELTS reproduces the experimental data better (Schwinger & Breuer, 2022).…”

Section: Methodsmentioning

confidence: 99%

“…They showed that the chemical evolution of the liquid and crystallizing solids can be reproduced best by a combination of SPICES (Davenport et al., 2014) and alphaMELTS (Smith & Asimow, 2005). We modeled the fractional crystallization of several LMO scenarios, adopting the modeling approach of Schwinger and Breuer (2022). The program FXMOTR from the software package SPICES was used for modeling the solidification of the first ~45% of the magma ocean until only olivine was present at the liquidus.…”

Section: Methodsmentioning

confidence: 99%

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Controls on determining the bulk water content of the Moon

Mallik

Schwinger

Roy

et al. 2022

Meteorit & Planetary Scien

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The Moon is much wetter than previously thought. The estimated bulk H2O concentrations based on the analyses of H2O in lunar materials show a wide range from 5 to 1650 ppm. To better constrain bulk H2O in the lunar magma ocean (LMO), we model LMO crystallization and vary DH (concentration of H2O in LMO mineral/concentration of H2O in melt), interstitial melt fraction, and initial LMO depth. We take the highest and lowest values of DH reported in the literature for the LMO minerals. We assess the bulk H2O content required in the initial magma ocean to satisfy two observational constraints: (1) H2O measured in plagioclase grains from ferroan anorthosites and (2) crustal mass from GRAIL. We find that the initial bulk LMO H2O that best explains the H2O content in crustal plagioclase is strongly dependent on DH rather than interstitial melt fractions or initial LMO depths, with a drier magma ocean (10 ppm H2O) being favored with higher DH and a wetter magma ocean (100–1000 ppm H2O) with lower DH. This underscores the importance of constraining DH specific to lunar conditions in future studies. We also demonstrate that crustal mass is not an effective hygrometer.

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Employing magma ocean crystallization models to constrain structure and composition of the lunar interior

Cited by 10 publications

References 77 publications

Experimental Evidence Supporting an Overturned Iron‐Titanium‐Rich Melt Layer in the Deep Lunar Interior

Experimental Evidence Supporting an Overturned Iron‐Titanium‐Rich Melt Layer in the Deep Lunar Interior

The Volcanic and Radial Expansion/Contraction History of the Moon Simulated by Numerical Models of Magmatism in the Convective Mantle

Controls on determining the bulk water content of the Moon

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