Lunar

@misc{newton1969secular9,
    author = "Newton, R",
    title = "Secular variations of the earth and moon",
    year = "1969",
    howpublished = "Science, v. 166, p. 825-831",
    note = "talkorigins\_source = {true}; raw\_reference = {Newton, R., 1969, Secular variations of the earth and moon: Science, v. 166, p. 825-831.}"
}

@misc{goldreich1972tides5,
    author = "Goldreich, P",
    title = "Tides and the earth-moon system",
    year = "1972",
    howpublished = "Scientific American, v. 226, no. 4, p. 43-52",
    note = "talkorigins\_source = {true}; raw\_reference = {Goldreich, P., 1972, Tides and the earth-moon system: Scientific American, v. 226, no. 4, p. 43-52.}"
}

@misc{turcotte1974evolution12,
    author = "Turcotte, D. L. and Nordmann, J. C. and Cisne, J. L",
    title = "Evolution of the Moon's orbit and the origin of life",
    year = "1974",
    howpublished = "Nature, v. 251, p. 124-125",
    note = "talkorigins\_source = {true}; raw\_reference = {Turcotte, D. L., Nordmann, J. C., and Cisne, J. L., 1974, Evolution of the Moon's orbit and the origin of life: Nature, v. 251, p. 124-125.}"
}

@article{doi1010160019103575900706,
    author = "Hartmann, W. K. and Davis, Donald R.",
    title = "Satellite-sized planetesimals and lunar origin",
    year = "1975",
    journal = "Icarus",
    url = "https://doi.org/10.1016/0019-1035(75)90070-6",
    doi = "10.1016/0019-1035(75)90070-6",
    openalex = "W2067432880"
}

@book{taylor1975lunar11,
    author = "Taylor, S. R",
    title = "Lunar Science",
    year = "1975",
    publisher = "A Post-Apollo View: New York, Pergamon Press",
    note = "talkorigins\_source = {true}; raw\_reference = {Taylor, S. R., 1975, Lunar Science: A Post-Apollo View: New York, Pergamon Press.}"
}

@misc{kahn1978nautiloid6,
    author = "Kahn, P. G. H. and Pompea, S. M",
    title = "Nautiloid growth and dynamical evolution of the Earth-Moon system",
    year = "1978",
    howpublished = "Nature, v. 275, no. 5681, p. 606-611",
    note = "talkorigins\_source = {true}; raw\_reference = {Kahn, P. G. H., and Pompea, S. M., 1978, Nautiloid growth and dynamical evolution of the Earth-Moon system: Nature, v. 275, no. 5681, p. 606-611.}"
}

@misc{west1978moon13,
    author = "West, S",
    title = "Moon history in a sea shell",
    year = "1978",
    howpublished = "Science News, v. 114, p. 426-428",
    note = "talkorigins\_source = {true}; raw\_reference = {West, S., 1978, Moon history in a sea shell: Science News, v. 114, p. 426-428.}"
}

@misc{deyoung1979the2,
    author = "DeYoung, D. B",
    title = "The moon",
    year = "1979",
    howpublished = "A faithful witness in the sky: ICR Impact Series, v. 68, p. i-iv",
    note = "talkorigins\_source = {true}; raw\_reference = {DeYoung, D. B., 1979, The moon: A faithful witness in the sky: ICR Impact Series, v. 68, p. i-iv.}"
}

@book{doi1010079781461261674,
    author = "Ringwood, A. E.",
    title = "Origin of the Earth and Moon",
    year = "1979",
    url = "https://doi.org/10.1007/978-1-4612-6167-4",
    doi = "10.1007/978-1-4612-6167-4",
    openalex = "W1600775227"
}

@misc{fox1981amino3,
    author = "Fox, S. W. and Harada, K. and Hare, P. E",
    title = "Amino acids from the Moon",
    year = "1981",
    howpublished = "Notes on meteorites: Subcellular Biochemistry, v. 8, p. 357-373",
    note = "talkorigins\_source = {true}; raw\_reference = {Fox, S. W., Harada, K., and Hare, P. E., 1981, Amino acids from the Moon: Notes on meteorites: Subcellular Biochemistry, v. 8, p. 357-373.}"
}

@misc{french1981the4,
    author = "French, B. M",
    title = "The Moon, in Beatty, J. K., O'Leary, B., and Chaikin, A., eds., The New Solar System",
    year = "1981",
    howpublished = "Cambridge, Mass., Sky, p. 71-82",
    note = "talkorigins\_source = {true}; raw\_reference = {French, B. M., 1981, The Moon, in Beatty, J. K., O'Leary, B., and Chaikin, A., eds., The New Solar System: Cambridge, Mass., Sky, p. 71-82.}"
}

@misc{kerr1982where7,
    author = "Kerr, R. A",
    title = "Where was the moon eons ago?",
    year = "1982",
    howpublished = "Science, v. 221, p. 1166",
    note = "talkorigins\_source = {true}; raw\_reference = {Kerr, R. A., 1982, Where was the moon eons ago?: Science, v. 221, p. 1166.}"
}

@misc{awbery1983space1,
    author = "Awbery, F. T",
    title = "Space dust, the moon's surface, and the age of the cosmos",
    year = "1983",
    howpublished = "Creation/Evolution, v. 4, p. 21-29",
    note = "talkorigins\_source = {true}; raw\_reference = {Awbery, F. T., 1983, Space dust, the moon's surface, and the age of the cosmos: Creation/Evolution, v. 4, p. 21-29.}"
}

@misc{kerr1984making8,
    author = "Kerr, R. A",
    title = "Making the Moon from a big splash",
    year = "1984",
    howpublished = "Science, v. 226, p. 1060-1061",
    note = "talkorigins\_source = {true}; raw\_reference = {Kerr, R. A., 1984, Making the Moon from a big splash: Science, v. 226, p. 1060-1061.}"
}

THE MAGMA OCEAN CONCEPT AND LUNAR EVOLUTION, Page 1 of 1 /docserver/preview/fulltext/earth/13/1/annurev.ea.13.050185.001221-1.gif

@article{doi101146annurevea13050185001221,
    author = "Warren, P. H.",
    title = "THE MAGMA OCEAN CONCEPT AND LUNAR EVOLUTION",
    year = "1985",
    journal = "Annual Review of Earth and Planetary Sciences",
    abstract = "THE MAGMA OCEAN CONCEPT AND LUNAR EVOLUTION, Page 1 of 1 /docserver/preview/fulltext/earth/13/1/annurev.ea.13.050185.001221-1.gif",
    url = "https://doi.org/10.1146/annurev.ea.13.050185.001221",
    doi = "10.1146/annurev.ea.13.050185.001221",
    openalex = "W2101788954"
}

@misc{taylor1985lunar10,
    author = "Taylor, G. J",
    title = "Lunar origin meeting favors impact theory",
    year = "1985",
    howpublished = "Geotimes, v. 30, no. 4, p. 16-17",
    note = "talkorigins\_source = {true}; raw\_reference = {Taylor, G. J., 1985, Lunar origin meeting favors impact theory: Geotimes, v. 30, no. 4, p. 16-17.}"
}

@article{doi1010160019103586900886,
    author = "Benz, W. and Slattery, W. L. and Cameron, A. G. W.",
    title = "The origin of the moon and the single-impact hypothesis I",
    year = "1986",
    journal = "Icarus",
    url = "https://doi.org/10.1016/0019-1035(86)90088-6",
    doi = "10.1016/0019-1035(86)90088-6",
    openalex = "W4256175005",
    references = "doi1010160019103583900325"
}

@article{doi1010160019103589901292,
    author = "Benz, W. and Cameron, A. G. W. and Melosh, H. J.",
    title = "The origin of the Moon and the single-impact hypothesis III",
    year = "1989",
    journal = "Icarus",
    url = "https://doi.org/10.1016/0019-1035(89)90129-2",
    doi = "10.1016/0019-1035(89)90129-2",
    openalex = "W2014157843",
    references = "doi1010160016703789901506, doi1010160019103583900325, doi1010160022286070900190"
}

The maturing of the Earth sciences has led to a fragmentation into subdisciplines which speak imperfectly to one another. Some of these subdisciplines are field geology, petrology, mineralogy, geochemistry, geodesy and seismology, and these in turn are split into even finer units. The science has also expanded to include the planets and even the cosmos. The practitioners in each of these fields tend to view the Earth in a completely different way. Discoveries in one field diffuse only slowly into the consciousness of a specialist in another. In spite of the fact that there is only one Earth, there are probably more Theories of the Earth than there are of astronomy, particle physics or cell biology where there are uncountable samples of each object. Even where there is cross-talk among disciplines, it is usually as noisy as static. Too often, one discipline's unproven assumptions or dogmas are treated as firm boundary conditions for a theoretician in a slightly overlapping area. The data of each subdiscipline are usually consistent with a range of hypotheses. The possibilities can be narrowed considerably as more and more diverse data are brought to bear on a particular problem. The questions of origin, composition and evolution of the Earth require input from astronomy, cosmochemistry, meteoritics, planetology, geology, petrology, mineralogy, crystallography, materials science and seismology, at a minimum. To a student of the Earth, these are artificial divisions, however necessary they are to make progress on a given front. \n \nIn Theory of the Earth I attempt to assemble the bits and pieces from a variety of disciplines which are relevant to an understanding of the Earth. Rocks and magmas are our most direct source of information about the interior, but they are biased toward the properties of the crust and shallow mantle. Seismology is our best source of information about the deep interior; however, the interpretation of seismic data for purposes other than purely structural requires input from solid-state physics and experimental petrology. Although this is not a book about seismology, it uses seismology in a variety of ways. \n \nThe "Theory of the Earth" developed here differs in many respects from conventional views. Petrologists' models for the Earth's interior usually focus on the composition of mantle samples contained in basalts and kimberlites. The simplest hypothesis based on these samples is that the observed basalts and peridotites bear a complementary relation to one another, that peridotites are the source of basalts or the residue after their removal, and that the whole mantle is identical in composition to the inferred chemistry of the upper mantle and the basalt source region. The mantle is therefore homogeneous in composition, and thus all parts of the mantle eventually rise to the surface to provide basalts. Subducted slabs experience no barrier in falling through the mantle to the core-mantle boundary.

@book{openalexw1563457350,
    author = "Anderson, Don L.",
    title = "Theory of the Earth",
    year = "1989",
    booktitle = "CaltechAUTHORS (California Institute of Technology)",
    abstract = {The maturing of the Earth sciences has led to a fragmentation into subdisciplines which speak imperfectly to one another. Some of these subdisciplines are field geology, petrology, mineralogy, geochemistry, geodesy and seismology, and these in turn are split into even finer units. The science has also expanded to include the planets and even the cosmos. The practitioners in each of these fields tend to view the Earth in a completely different way. Discoveries in one field diffuse only slowly into the consciousness of a specialist in another. In spite of the fact that there is only one Earth, there are probably more Theories of the Earth than there are of astronomy, particle physics or cell biology where there are uncountable samples of each object. Even where there is cross-talk among disciplines, it is usually as noisy as static. Too often, one discipline's unproven assumptions or dogmas are treated as firm boundary conditions for a theoretician in a slightly overlapping area. The data of each subdiscipline are usually consistent with a range of hypotheses. The possibilities can be narrowed considerably as more and more diverse data are brought to bear on a particular problem. The questions of origin, composition and evolution of the Earth require input from astronomy, cosmochemistry, meteoritics, planetology, geology, petrology, mineralogy, crystallography, materials science and seismology, at a minimum. To a student of the Earth, these are artificial divisions, however necessary they are to make progress on a given front. \n \nIn Theory of the Earth I attempt to assemble the bits and pieces from a variety of disciplines which are relevant to an understanding of the Earth. Rocks and magmas are our most direct source of information about the interior, but they are biased toward the properties of the crust and shallow mantle. Seismology is our best source of information about the deep interior; however, the interpretation of seismic data for purposes other than purely structural requires input from solid-state physics and experimental petrology. Although this is not a book about seismology, it uses seismology in a variety of ways. \n \nThe "Theory of the Earth" developed here differs in many respects from conventional views. Petrologists' models for the Earth's interior usually focus on the composition of mantle samples contained in basalts and kimberlites. The simplest hypothesis based on these samples is that the observed basalts and peridotites bear a complementary relation to one another, that peridotites are the source of basalts or the residue after their removal, and that the whole mantle is identical in composition to the inferred chemistry of the upper mantle and the basalt source region. The mantle is therefore homogeneous in composition, and thus all parts of the mantle eventually rise to the surface to provide basalts. Subducted slabs experience no barrier in falling through the mantle to the core-mantle boundary.},
    openalex = "W1563457350",
    references = "doi1010079781461261674, doi1010079783642680120, doi1010160012825268901475, doi1010160031920181900467, doi101029jb079i035p05507, doi101029jb082i005p00803, doi101029jb089ib07p05929, doi101029jb089ib07p05987, doi101029jb089ib07p06003, doi101029rg013i003p00001, doi101029rg016i004p00621, doi101038297391a0, doi101038309753a0, doi10111513423694, doi101126science2214611651, doi101130mem97, doi10119011442051, doi102307jctvw1d7dg9, openalexw1572130436, openalexw1604427421, openalexw1624806571"
}

@article{doi101016001910359190046v,
    author = "Cameron, A. G. W. and Benz, W.",
    title = "The origin of the moon and the single impact hypothesis IV",
    year = "1991",
    journal = "Icarus",
    url = "https://doi.org/10.1016/0019-1035(91)90046-v",
    doi = "10.1016/0019-1035(91)90046-v",
    openalex = "W4232459068",
    references = "doi1010160019103583900325"
}

@article{doi1010160012821x95001383,
    author = "Hess, P. C. and Parmentier, E. M.",
    title = "A model for the thermal and chemical evolution of the Moon's interior: implications for the onset of mare volcanism",
    year = "1995",
    journal = "Earth and Planetary Science Letters",
    url = "https://doi.org/10.1016/0012-821x(95)00138-3",
    doi = "10.1016/0012-821x(95)00138-3",
    openalex = "W1996895446"
}

The derivation of quantitative elemental concentrations from multispectral imaging of the Moon has long been a goal of lunar remote sensing. Concentration maps at the spatial resolutions available from the recent Clementine mission would provide a revolutionary new tool for understanding the origin and evolution of the lunar crust. Lucey et al. [1995] presented a method for extracting the concentration of Fe from multispectral imaging of the Moon. This paper examines and quantifies important aspects ofthat technique left unexamined by Lucey et al. which had the potential to severely limit its utility. These aspects include the effects of maturity, grain size, mineralogy, shading due to topography, and the presence of glass. We also present a new algorithm for derivation of TiO 2 from multispectral imaging of both mare and highland units. We find that both techniques are only weakly sensitive to maturity and that they have about 1 wt % accuracy based on examination of the spectral properties and compositions of resolved lunar sampling stations presented by Blewett et al. [1997]. We also discuss these findings in the context of two contrasting views of the effect of composition on lunar spectral properties presented by Pieters and coworkers and Hapke and coworkers. We find the view of Hapke and coworkers to be more consistent with our observations. Using a global mosaic of Clementine multispectral data and these element derivation algorithms, we find that the global modal abundance of FeO is 4.5 wt %±1 wt % and the global modal abundance of TiO 2 is 0.45 wt %±1 wt. %.

@article{doi10102997je03019,
    author = "Lucey, P. G. and Blewett, D. T. and Hawke, B. R.",
    title = "Mapping the FeO and TiO 2 content of the lunar surface with multispectral imagery",
    year = "1998",
    journal = "Journal of Geophysical Research Atmospheres",
    abstract = "The derivation of quantitative elemental concentrations from multispectral imaging of the Moon has long been a goal of lunar remote sensing. Concentration maps at the spatial resolutions available from the recent Clementine mission would provide a revolutionary new tool for understanding the origin and evolution of the lunar crust. Lucey et al. [1995] presented a method for extracting the concentration of Fe from multispectral imaging of the Moon. This paper examines and quantifies important aspects ofthat technique left unexamined by Lucey et al. which had the potential to severely limit its utility. These aspects include the effects of maturity, grain size, mineralogy, shading due to topography, and the presence of glass. We also present a new algorithm for derivation of TiO 2 from multispectral imaging of both mare and highland units. We find that both techniques are only weakly sensitive to maturity and that they have about 1 wt \% accuracy based on examination of the spectral properties and compositions of resolved lunar sampling stations presented by Blewett et al. [1997]. We also discuss these findings in the context of two contrasting views of the effect of composition on lunar spectral properties presented by Pieters and coworkers and Hapke and coworkers. We find the view of Hapke and coworkers to be more consistent with our observations. Using a global mosaic of Clementine multispectral data and these element derivation algorithms, we find that the global modal abundance of FeO is 4.5 wt \%±1 wt \% and the global modal abundance of TiO 2 is 0.45 wt \%±1 wt. \%.",
    url = "https://doi.org/10.1029/97je03019",
    doi = "10.1029/97je03019",
    openalex = "W2075351638"
}

Geophysical, remote‐sensing, and sample data demonstrate that the Procellarum and Imbrium regions of the Moon make up a unique geochemical crustal province (here dubbed the Procellarum KREEP Terrane). Geochemical studies of Imbrium's ejecta and the crustal structure of the Imbrium and Serenitatis basins both suggest that a large portion of the lunar crust in this locale is composed of a material similar in composition to Apollo 15 KREEP basalt. KREEP basalt has about 300 times more uranium and thorium than chondrites, so this implies that a large portion of Moon's heat‐producing elements is located within this single crustal province. The spatial distribution of mare volcanism closely parallels the confines of the Procellarum KREEP Terrane and this suggests a causal relationship between the two phenomena. We have modeled the Moon's thermal evolution using a simple thermal conduction model and show that as a result of the high abundance of heat‐producing elements that are found in the Procellarum KREEP Terrane, partial melting of the underlying mantle is an inevitable outcome. Specifically, by placing a 10‐km KREEP basalt layer at the base of the crust there, our model predicts that mare volcanism should span most of the Moon's history and that the depth of melting should increase with time to a maximum depth of about 600 km. We suggest that the 500‐km seismic discontinuity that is observed in the Apollo seismic data may represent this maximum depth of melting. Our model also predicts that the KREEP basalt layer should remain partially molten for a few billion years. Thus the Imbrium impact event most likely excavated into a partially molten KREEP basalt magma chamber. We postulate that the KREEP basalt composition is a by‐product of mixing urKREEP with shallow partial melts of the underlying mantle. Since Mg‐suite rocks are likely derived from crystallizing KREEP basalt, the provenance of these plutonic rocks is likely to be unique to this region of the Moon.

@article{doi1010291999je001092,
    author = "Wieczorek, M. A. and Phillips, R. J.",
    title = "The “Procellarum KREEP Terrane”: Implications for mare volcanism and lunar evolution",
    year = "2000",
    journal = "Journal of Geophysical Research Atmospheres",
    abstract = "Geophysical, remote‐sensing, and sample data demonstrate that the Procellarum and Imbrium regions of the Moon make up a unique geochemical crustal province (here dubbed the Procellarum KREEP Terrane). Geochemical studies of Imbrium's ejecta and the crustal structure of the Imbrium and Serenitatis basins both suggest that a large portion of the lunar crust in this locale is composed of a material similar in composition to Apollo 15 KREEP basalt. KREEP basalt has about 300 times more uranium and thorium than chondrites, so this implies that a large portion of Moon's heat‐producing elements is located within this single crustal province. The spatial distribution of mare volcanism closely parallels the confines of the Procellarum KREEP Terrane and this suggests a causal relationship between the two phenomena. We have modeled the Moon's thermal evolution using a simple thermal conduction model and show that as a result of the high abundance of heat‐producing elements that are found in the Procellarum KREEP Terrane, partial melting of the underlying mantle is an inevitable outcome. Specifically, by placing a 10‐km KREEP basalt layer at the base of the crust there, our model predicts that mare volcanism should span most of the Moon's history and that the depth of melting should increase with time to a maximum depth of about 600 km. We suggest that the 500‐km seismic discontinuity that is observed in the Apollo seismic data may represent this maximum depth of melting. Our model also predicts that the KREEP basalt layer should remain partially molten for a few billion years. Thus the Imbrium impact event most likely excavated into a partially molten KREEP basalt magma chamber. We postulate that the KREEP basalt composition is a by‐product of mixing urKREEP with shallow partial melts of the underlying mantle. Since Mg‐suite rocks are likely derived from crystallizing KREEP basalt, the provenance of these plutonic rocks is likely to be unique to this region of the Moon.",
    url = "https://doi.org/10.1029/1999je001092",
    doi = "10.1029/1999je001092",
    openalex = "W2152643502",
    references = "doi1010291999je001103"
}

In light of global remotely sensed data, the igneous crust of the Moon can no longer be viewed as a simple, globally stratified cumulus structure, composed of a flotation upper crust of anorthosite underlain by progressively more mafic rocks and a residual‐melt (KREEP) sandwich horizon near the base of the lower crust. Instead, global geochemical information derived from Clementine multispectral data and Lunar Prospector gamma‐ray data reveals at least three distinct provinces whose geochemistry and petrologic history make them geologically unique: (1) the Procellarum KREEP Terrane (PKT), (2) the Feldspathic High‐lands Terrane (FHT), and (3) the South Pole‐Aitken Terrane (SPAT). The PKT is a mafic province, coincident with the largely resurfaced area in the Procellarum‐Imbrium region whose petrogenesis relates to the early differentiation of the Moon. Here, some 40% of the Th in the Moon's crust is concentrated into a region that constitutes only about 10% of the crustal volume. This concentration of Th (average ∼5 ppm), and by implication the other heat producing elements, U and K, led to a fundamentally different thermal and igneous evolution within this region compared to other parts of the lunar crust. Lower‐crustal materials within the PKT likely interacted with underlying mantle materials to produce hybrid magmatism, leading to the magnesian suite of lunar rocks and possibly KREEP basalt. Although rare in the Apollo sample collection, widespread mare volcanic rocks having substantial Th enrichment are indicated by the remote data and may reflect further interaction between enriched crustal residues and mantle sources. The FHT is characterized by a central anorthositic region that constitutes the remnant of an anorthositic craton resulting from early lunar differentiation. Basin impacts into this region do not excavate significantly more mafic material, suggesting a thickness of tens of kilometers of anorthositic crust. The feldspathic lunar meteorites may represent samples from the anorthositic central region of the FHT. Ejecta from deep‐penetrating basin impacts outside of the central anorthositic region, however, indicate an increasingly mafic composition with depth. The SPAT, a mafic anomaly of great magnitude, may include material of the upper mantle as well as lower crust; thus it is designated a separate terrane. Whether the SPA basin impact simply uncovered lower crust such as we infer for the FHT remains to be determined.

@article{doi1010291999je001103,
    author = "Jolliff, Bradley L. and Gillis, Jeffrey J. and Haskin, L. A. and Korotev, R. L. and Wieczorek, M. A.",
    title = "Major lunar crustal terranes: Surface expressions and crust‐mantle origins",
    year = "2000",
    journal = "Journal of Geophysical Research Atmospheres",
    abstract = "In light of global remotely sensed data, the igneous crust of the Moon can no longer be viewed as a simple, globally stratified cumulus structure, composed of a flotation upper crust of anorthosite underlain by progressively more mafic rocks and a residual‐melt (KREEP) sandwich horizon near the base of the lower crust. Instead, global geochemical information derived from Clementine multispectral data and Lunar Prospector gamma‐ray data reveals at least three distinct provinces whose geochemistry and petrologic history make them geologically unique: (1) the Procellarum KREEP Terrane (PKT), (2) the Feldspathic High‐lands Terrane (FHT), and (3) the South Pole‐Aitken Terrane (SPAT). The PKT is a mafic province, coincident with the largely resurfaced area in the Procellarum‐Imbrium region whose petrogenesis relates to the early differentiation of the Moon. Here, some 40\% of the Th in the Moon's crust is concentrated into a region that constitutes only about 10\% of the crustal volume. This concentration of Th (average ∼5 ppm), and by implication the other heat producing elements, U and K, led to a fundamentally different thermal and igneous evolution within this region compared to other parts of the lunar crust. Lower‐crustal materials within the PKT likely interacted with underlying mantle materials to produce hybrid magmatism, leading to the magnesian suite of lunar rocks and possibly KREEP basalt. Although rare in the Apollo sample collection, widespread mare volcanic rocks having substantial Th enrichment are indicated by the remote data and may reflect further interaction between enriched crustal residues and mantle sources. The FHT is characterized by a central anorthositic region that constitutes the remnant of an anorthositic craton resulting from early lunar differentiation. Basin impacts into this region do not excavate significantly more mafic material, suggesting a thickness of tens of kilometers of anorthositic crust. The feldspathic lunar meteorites may represent samples from the anorthositic central region of the FHT. Ejecta from deep‐penetrating basin impacts outside of the central anorthositic region, however, indicate an increasingly mafic composition with depth. The SPAT, a mafic anomaly of great magnitude, may include material of the upper mantle as well as lower crust; thus it is designated a separate terrane. Whether the SPA basin impact simply uncovered lower crust such as we infer for the FHT remains to be determined.",
    url = "https://doi.org/10.1029/1999je001103",
    doi = "10.1029/1999je001103",
    openalex = "W2071619825",
    references = "doi1010160012821x95001383, doi101016001670378990286x, doi101016016093279290014g, doi1010291999je001092, doi10102997je03019, doi10102997je03136, doi101126science26651921835, doi101126science26651921839, doi101126science26852141150, openalexw2302969081"
}

Abstract— In the primordial solar system, the most plausible sources of the water accreted by the Earth were in the outer asteroid belt, in the giant planet regions, and in the Kuiper Belt. We investigate the implications on the origin of Earth's water of dynamical models of primordial evolution of solar system bodies and check them with respect to chemical constraints. We find that it is plausible that the Earth accreted water all along its formation, from the early phases when the solar nebula was still present to the late stages of gas‐free sweepup of scattered planetesimals. Asteroids and the comets from the Jupiter‐Saturn region were the first water deliverers, when the Earth was less than half its present mass. The bulk of the water presently on Earth was carried by a few planetary embryos, originally formed in the outer asteroid belt and accreted by the Earth at the final stage of its formation. Finally, a late veneer, accounting for at most 10% of the present water mass, occurred due to comets from the Uranus‐Neptune region and from the Kuiper Belt. The net result of accretion from these several reservoirs is that the water on Earth had essentially the D/H ratio typical of the water condensed in the outer asteroid belt. This is in agreement with the observation that the D/H ratio in the oceans is very close to the mean value of the D/H ratio of the water inclusions in carbonaceous chondrites.

@article{doi101111j194551002000tb01518x,
    author = "Morbidelli, Alessandro and Chambers, John and Lunine, J. I. and Petit, Jean-Marc and Robert, F. and Valsecchi, G. B. and Cyr, K. E.",
    title = "Source regions and timescales for the delivery of water to the Earth",
    year = "2000",
    journal = "Meteoritics and Planetary Science",
    abstract = "Abstract— In the primordial solar system, the most plausible sources of the water accreted by the Earth were in the outer asteroid belt, in the giant planet regions, and in the Kuiper Belt. We investigate the implications on the origin of Earth's water of dynamical models of primordial evolution of solar system bodies and check them with respect to chemical constraints. We find that it is plausible that the Earth accreted water all along its formation, from the early phases when the solar nebula was still present to the late stages of gas‐free sweepup of scattered planetesimals. Asteroids and the comets from the Jupiter‐Saturn region were the first water deliverers, when the Earth was less than half its present mass. The bulk of the water presently on Earth was carried by a few planetary embryos, originally formed in the outer asteroid belt and accreted by the Earth at the final stage of its formation. Finally, a late veneer, accounting for at most 10\% of the present water mass, occurred due to comets from the Uranus‐Neptune region and from the Kuiper Belt. The net result of accretion from these several reservoirs is that the water on Earth had essentially the D/H ratio typical of the water condensed in the outer asteroid belt. This is in agreement with the observation that the D/H ratio in the oceans is very close to the mean value of the D/H ratio of the water inclusions in carbonaceous chondrites.",
    url = "https://doi.org/10.1111/j.1945-5100.2000.tb01518.x",
    doi = "10.1111/j.1945-5100.2000.tb01518.x",
    openalex = "W2014359877",
    references = "doi101006icar19941039, doi101006icar19960190, doi101006icar19986007, doi101006icar19996299, doi1010079781461261674, doi101007bf00642464, doi1010160019103588900310, doi101016001910359190036s, doi101017cbo9780511545986, doi101126science25550501391, doi101126science27653191670"
}

@article{doi10103835089010,
    author = "Canup, R. M. and Asphaug, Erik",
    title = "Origin of the Moon in a giant impact near the end of the Earth's formation",
    year = "2001",
    journal = "Nature",
    url = "https://doi.org/10.1038/35089010",
    doi = "10.1038/35089010",
    openalex = "W2043818941",
    references = "doi101006icar19960083, doi101006icar20006581, doi1010160019103575900706, doi1010160019103586900886, doi1010160019103589901292, doi101016001910359190046v, doi10103838669, doi101086112164, doi101086191344, openalexw139796423"
}

▪ Abstract The giant impact theory is the leading hypothesis for the origin of the Moon. This review focuses on dynamical aspects of an impact-induced lunar formation, in particular those areas that have advanced considerably in the past decade, including (a) late-stage terrestrial accretion, (b) giant impact simulations, (c) protolunar disk evolution and lunar accretion, and (d) the origin of the initial lunar inclination. In all, recent developments now provide a reasonably consistent dynamical account of the origin of the Moon through a late giant impact with Earth, and suggest that the impact-generation of satellites is likely to be a common process in late-stage solid planet formation.

@article{doi101146annurevastro41082201113457,
    author = "Canup, R. M.",
    title = "Dynamics of Lunar Formation",
    year = "2004",
    journal = "Annual Review of Astronomy and Astrophysics",
    abstract = "▪ Abstract The giant impact theory is the leading hypothesis for the origin of the Moon. This review focuses on dynamical aspects of an impact-induced lunar formation, in particular those areas that have advanced considerably in the past decade, including (a) late-stage terrestrial accretion, (b) giant impact simulations, (c) protolunar disk evolution and lunar accretion, and (d) the origin of the initial lunar inclination. In all, recent developments now provide a reasonably consistent dynamical account of the origin of the Moon through a late giant impact with Earth, and suggest that the impact-generation of satellites is likely to be a common process in late-stage solid planet formation.",
    url = "https://doi.org/10.1146/annurev.astro.41.082201.113457",
    doi = "10.1146/annurev.astro.41.082201.113457",
    openalex = "W2140944900",
    references = "doi101006icar20016639, doi101007978940102585013, doi1010160019103575900706, doi10103835089010, doi101038nature00982, doi101046j13658711199902379x, doi101086112164, doi101086115978, doi101086158356, doi101146annurevaa30090192002551"
}

The main objective of the present study is to discuss in detail the results obtained from an inversion of the Apollo lunar seismic data set, lunar mass, and moment of inertia. We inverted directly for lunar chemical composition and temperature using the model system CaO‐FeO‐MgO‐Al 2 O 3 ‐SiO 2. Using Gibbs free energy minimization, stable mineral phases at the temperatures and pressures of interest, their modes and physical properties are calculated. We determine the compositional range of the oxide elements, thermal state, Mg#, mineralogy and physical structure of the lunar interior, as well as constraining core size and density. The results indicate a lunar mantle mineralogy that is dominated by olivine and orthopyroxene (−80 vol%), with the remainder being composed of clinopyroxene and an aluminous phase (plagioclase, spinel, and garnet present in the depth ranges 0–150 km, 150–200 km, and >200 km, respectively). This model is broadly consistent with constraints on mantle mineralogy derived from the experimental and observational study of the phase relationships and trace element compositions of lunar mare basalts and picritic glasses. In particular, by melting a typical model mantle composition using the pMELTS algorithm, we found that a range of batch melts generated from these models have features in common with low Ti mare basalts and picritic glasses. Our results also indicate a bulk lunar composition and Mg# different to that of the Earth's upper mantle, represented by the pyrolite composition. This difference is reflected in a lower bulk lunar Mg# (−0.83). Results also indicate a small iron‐like core with a radius around 340 km.

@article{doi1010292005je002608,
    author = "Khan, A. and Maclennan, John and Taylor, S. R. and Connolly, J. A. D.",
    title = "Are the Earth and the Moon compositionally alike? Inferences on lunar composition and implications for lunar origin and evolution from geophysical modeling",
    year = "2006",
    journal = "Journal of Geophysical Research Atmospheres",
    abstract = "The main objective of the present study is to discuss in detail the results obtained from an inversion of the Apollo lunar seismic data set, lunar mass, and moment of inertia. We inverted directly for lunar chemical composition and temperature using the model system CaO‐FeO‐MgO‐Al 2 O 3 ‐SiO 2. Using Gibbs free energy minimization, stable mineral phases at the temperatures and pressures of interest, their modes and physical properties are calculated. We determine the compositional range of the oxide elements, thermal state, Mg\#, mineralogy and physical structure of the lunar interior, as well as constraining core size and density. The results indicate a lunar mantle mineralogy that is dominated by olivine and orthopyroxene (−80 vol\%), with the remainder being composed of clinopyroxene and an aluminous phase (plagioclase, spinel, and garnet present in the depth ranges 0–150 km, 150–200 km, and >200 km, respectively). This model is broadly consistent with constraints on mantle mineralogy derived from the experimental and observational study of the phase relationships and trace element compositions of lunar mare basalts and picritic glasses. In particular, by melting a typical model mantle composition using the pMELTS algorithm, we found that a range of batch melts generated from these models have features in common with low Ti mare basalts and picritic glasses. Our results also indicate a bulk lunar composition and Mg\# different to that of the Earth's upper mantle, represented by the pyrolite composition. This difference is reflected in a lower bulk lunar Mg\# (−0.83). Results also indicate a small iron‐like core with a radius around 340 km.",
    url = "https://doi.org/10.1029/2005je002608",
    doi = "10.1029/2005je002608",
    openalex = "W2161379573",
    references = "doi1010079781461261674, doi101007bf00307281, doi1010160009254194001404, doi101016jepsl200504033, doi1010291999je001103, doi1010292003gc000597, doi10102994jb03097, doi10103835089010, doi101111j194551001990tb00717x, openalexw1574224119"
}

@article{doi102138rmg2006604,
    author = "Shearer, C. K.",
    title = "Thermal and Magmatic Evolution of the Moon",
    year = "2006",
    journal = "Reviews in Mineralogy and Geochemistry",
    url = "https://doi.org/10.2138/rmg.2006.60.4",
    doi = "10.2138/rmg.2006.60.4",
    openalex = "W2122195812",
    references = "doi1010291999je001103, doi10103835089010"
}

The main objective of the present study is to discuss in detail the results obtained from an inversion of the Apollo lunar seismic data set, lunar mass, and moment of inertia. We inverted directly for lunar chemical composition and temperature using the model system CaO‐FeO‐MgO‐Al 2 O 3 ‐SiO 2. Using Gibbs free energy minimization, stable mineral phases at the temperatures and pressures of interest, their modes and physical properties are calculated. We determine the compositional range of the oxide elements, thermal state, Mg#, mineralogy and physical structure of the lunar interior, as well as constraining core size and density. The results indicate a lunar mantle mineralogy that is dominated by olivine and orthopyroxene (−80 vol%), with the remainder being composed of clinopyroxene and an aluminous phase (plagioclase, spinel, and garnet present in the depth ranges 0–150 km, 150–200 km, and >200 km, respectively). This model is broadly consistent with constraints on mantle mineralogy derived from the experimental and observational study of the phase relationships and trace element compositions of lunar mare basalts and picritic glasses. In particular, by melting a typical model mantle composition using the pMELTS algorithm, we found that a range of batch melts generated from these models have features in common with low Ti mare basalts and picritic glasses. Our results also indicate a bulk lunar composition and Mg# different to that of the Earth's upper mantle, represented by the pyrolite composition. This difference is reflected in a lower bulk lunar Mg# (−0.83). Results also indicate a small iron‐like core with a radius around 340 km.

@article{khan2006are,
    author = "Khan, A. and Maclennan, J. and Taylor, S. R. and Connolly, J. A. D.",
    title = "Are the Earth and the Moon compositionally alike? Inferences on lunar composition and implications for lunar origin and evolution from geophysical modeling",
    year = "2006",
    journal = "Journal of Geophysical Research: Planets",
    abstract = "The main objective of the present study is to discuss in detail the results obtained from an inversion of the Apollo lunar seismic data set, lunar mass, and moment of inertia. We inverted directly for lunar chemical composition and temperature using the model system CaO‐FeO‐MgO‐Al 2 O 3 ‐SiO 2. Using Gibbs free energy minimization, stable mineral phases at the temperatures and pressures of interest, their modes and physical properties are calculated. We determine the compositional range of the oxide elements, thermal state, Mg\#, mineralogy and physical structure of the lunar interior, as well as constraining core size and density. The results indicate a lunar mantle mineralogy that is dominated by olivine and orthopyroxene (−80 vol\%), with the remainder being composed of clinopyroxene and an aluminous phase (plagioclase, spinel, and garnet present in the depth ranges 0–150 km, 150–200 km, and >200 km, respectively). This model is broadly consistent with constraints on mantle mineralogy derived from the experimental and observational study of the phase relationships and trace element compositions of lunar mare basalts and picritic glasses. In particular, by melting a typical model mantle composition using the pMELTS algorithm, we found that a range of batch melts generated from these models have features in common with low Ti mare basalts and picritic glasses. Our results also indicate a bulk lunar composition and Mg\# different to that of the Earth's upper mantle, represented by the pyrolite composition. This difference is reflected in a lower bulk lunar Mg\# (−0.83). Results also indicate a small iron‐like core with a radius around 340 km.",
    url = "https://doi.org/10.1029/2005je002608",
    doi = "10.1029/2005je002608",
    number = "E5",
    openalex = "W2161379573",
    volume = "111",
    references = "doi1010079781461261674, doi101007bf00307281, doi1010160009254194001404, doi101016jepsl200504033, doi1010291999je001103, doi1010292003gc000597, doi10102994jb03097, doi10103835089010, doi101111j194551001990tb00717x, openalexw1574224119"
}

@article{doi101016jepsl201110040,
    author = "Marty, Bernard",
    title = "The origins and concentrations of water, carbon, nitrogen and noble gases on Earth",
    year = "2011",
    journal = "Earth and Planetary Science Letters",
    url = "https://doi.org/10.1016/j.epsl.2011.10.040",
    doi = "10.1016/j.epsl.2011.10.040",
    openalex = "W2095245998",
    references = "doi1010160009254194001404, doi101016001670378990286x, doi101017cbo9780511545986, doi1010292003gc000597, doi101038nature00995, doi101038nature01073, doi101038nature03676, doi101038nature10201, doi101111j194551002000tb01518x, doi101130001676061951621111ghosw20co2"
}

@article{doi101038nature11507,
    author = "Paniello, Randal C. and Day, James M.D. and Moynier, Frédéric",
    title = "Zinc isotopic evidence for the origin of the Moon",
    year = "2012",
    journal = "Nature",
    url = "https://doi.org/10.1038/nature11507",
    doi = "10.1038/nature11507",
    openalex = "W2021930649"
}

A common origin for the Moon and Earth is required by their identical isotopic composition. However, simulations of the current giant impact hypothesis for Moon formation find that most lunar material originated from the impactor, which should have had a different isotopic signature. Previous Moon-formation studies assumed that the angular momentum after the impact was similar to that of the present day; however, Earth-mass planets are expected to have higher spin rates at the end of accretion. Here, we show that typical last giant impacts onto a fast-spinning proto-Earth can produce a Moon-forming disk derived primarily from Earth's mantle. Furthermore, we find that a faster-spinning early Earth-Moon system can lose angular momentum and reach the present state through an orbital resonance between the Sun and Moon.

@article{doi101126science1225542,
    author = "Ćuk, Matija and Stewart, Sarah T.",
    title = "Making the Moon from a Fast-Spinning Earth: A Giant Impact Followed by Resonant Despinning",
    year = "2012",
    journal = "Science",
    abstract = "A common origin for the Moon and Earth is required by their identical isotopic composition. However, simulations of the current giant impact hypothesis for Moon formation find that most lunar material originated from the impactor, which should have had a different isotopic signature. Previous Moon-formation studies assumed that the angular momentum after the impact was similar to that of the present day; however, Earth-mass planets are expected to have higher spin rates at the end of accretion. Here, we show that typical last giant impacts onto a fast-spinning proto-Earth can produce a Moon-forming disk derived primarily from Earth's mantle. Furthermore, we find that a faster-spinning early Earth-Moon system can lose angular momentum and reach the present state through an orbital resonance between the Sun and Moon.",
    url = "https://doi.org/10.1126/science.1225542",
    doi = "10.1126/science.1225542",
    openalex = "W2046557261",
    references = "doi10103835089010"
}

The Moon possesses a clear dichotomy in geological processes between the nearside and farside hemispheres. The most pronounced expressions of this dichotomy are the strong concentration of radioactive heat sources on the nearside in a region known as the Procellarum KREEP Terrane (PKT) and the mare basaltic lava flows that erupted in or adjacent to this terrane. We model the thermochemical evolution of the Moon using a 3‐D spherical thermochemical convection code in order to assess the consequences of a layer enriched in heat sources below the PKT on the Moon's global evolution. We find that in addition to localizing most of the melt production on the nearside, such an enriched concentration of heat sources in the PKT crust has an influence down to the core‐mantle boundary and leaves a present‐day temperature anomaly within the nearside mantle. Moderate gravitational and topographic anomalies that are predicted in the PKT, but not observed, may be masked either by crustal thinning or gravitational anomalies from dense material in the underlying mantle. Our models also predict crystallization of an inner core for sulfur concentrations less than 6 wt %.

@article{doi101002jgre20103,
    author = "Laneuville, M. and Wieczorek, M. A. and Breuer, D. and Tosi, Nicola",
    title = "Asymmetric thermal evolution of the Moon",
    year = "2013",
    journal = "Journal of Geophysical Research Planets",
    abstract = "The Moon possesses a clear dichotomy in geological processes between the nearside and farside hemispheres. The most pronounced expressions of this dichotomy are the strong concentration of radioactive heat sources on the nearside in a region known as the Procellarum KREEP Terrane (PKT) and the mare basaltic lava flows that erupted in or adjacent to this terrane. We model the thermochemical evolution of the Moon using a 3‐D spherical thermochemical convection code in order to assess the consequences of a layer enriched in heat sources below the PKT on the Moon's global evolution. We find that in addition to localizing most of the melt production on the nearside, such an enriched concentration of heat sources in the PKT crust has an influence down to the core‐mantle boundary and leaves a present‐day temperature anomaly within the nearside mantle. Moderate gravitational and topographic anomalies that are predicted in the PKT, but not observed, may be masked either by crustal thinning or gravitational anomalies from dense material in the underlying mantle. Our models also predict crystallization of an inner core for sulfur concentrations less than 6 wt \%.",
    url = "https://doi.org/10.1002/jgre.20103",
    doi = "10.1002/jgre.20103",
    openalex = "W1678890861",
    references = "doi101016jgca200606262, doi101046j1365246x200000189x, doi101126science1231507, doi101126science1231530"
}

Abstract Models in which the mantle of the Moon evolves from an initially stratified state following magma ocean solidification and overturn have been applied to address important features of long‐term thermal evolution of the Moon, including convective instability of overturned ilmenite‐bearing cumulates (IBC) at the lunar core‐mantle boundary, generation of mare basalts, core sulfur content and inner core radius, paleomagnetism, and the present‐day mantle structure. Whether a dense overturned IBC‐rich layer at the bottom of the mantle can become thermally unstable to generate a single upwelling is controlled largely by the temperature‐dependence of viscosity (the activation energy). Convective instability of the IBC‐rich layer controls the heat flux out the core and the presence of an internally generated magnetic field. A long period of (~700 Ma) high positive core‐mantle‐boundary (CMB) heat flux after the instability of the IBC‐rich layer is expected from our models. Present‐day deep mantle temperatures inferred from seismic and gravitational inversion constrain the magnitude of mantle viscosity from 5 × 10 19 to 1 × 10 21 Pa s. The CMB temperature and solidified inner core radius inferred from seismic reflection constrain the core sulfur content. Our evolution models with 5–10 wt % sulfur content can produce the observed 240 km radius inner core at the present day. The asymmetrical distribution of the deep moonquakes only in the nearside mantle could be explained as the remnant structure of the single chemical upwelling generated from IBC‐rich layer. Our evolution model after the overturn results in an early ~0.55 km expansion in radius for ~1000 Ma due to the radiogenic heating associated with IBC in the deep mantle and may provide a simple explanation for the early expansion inferred from the Gravity Recovery and Interior Laboratory mission.

@article{doi101002jgre20121,
    author = "Zhang, Nan and Parmentier, E. M. and Liang, Yan",
    title = "A 3‐D numerical study of the thermal evolution of the Moon after cumulate mantle overturn: The importance of rheology and core solidification",
    year = "2013",
    journal = "Journal of Geophysical Research Planets",
    abstract = "Abstract Models in which the mantle of the Moon evolves from an initially stratified state following magma ocean solidification and overturn have been applied to address important features of long‐term thermal evolution of the Moon, including convective instability of overturned ilmenite‐bearing cumulates (IBC) at the lunar core‐mantle boundary, generation of mare basalts, core sulfur content and inner core radius, paleomagnetism, and the present‐day mantle structure. Whether a dense overturned IBC‐rich layer at the bottom of the mantle can become thermally unstable to generate a single upwelling is controlled largely by the temperature‐dependence of viscosity (the activation energy). Convective instability of the IBC‐rich layer controls the heat flux out the core and the presence of an internally generated magnetic field. A long period of (\textasciitilde 700 Ma) high positive core‐mantle‐boundary (CMB) heat flux after the instability of the IBC‐rich layer is expected from our models. Present‐day deep mantle temperatures inferred from seismic and gravitational inversion constrain the magnitude of mantle viscosity from 5 × 10 19 to 1 × 10 21 Pa s. The CMB temperature and solidified inner core radius inferred from seismic reflection constrain the core sulfur content. Our evolution models with 5–10 wt \% sulfur content can produce the observed 240 km radius inner core at the present day. The asymmetrical distribution of the deep moonquakes only in the nearside mantle could be explained as the remnant structure of the single chemical upwelling generated from IBC‐rich layer. Our evolution model after the overturn results in an early \textasciitilde 0.55 km expansion in radius for \textasciitilde 1000 Ma due to the radiogenic heating associated with IBC in the deep mantle and may provide a simple explanation for the early expansion inferred from the Gravity Recovery and Interior Laboratory mission.",
    url = "https://doi.org/10.1002/jgre.20121",
    doi = "10.1002/jgre.20121",
    openalex = "W2134484318",
    references = "doi1010292005je002608, khan2006are"
}

In this study we have measured the OH contents and D/H ratios in apatite grains in lunar basalts. These new data considerably expand the limited dataset published so far. The data presented in this study also show that there is a major difference between high- and low-Ti mare basalts in terms of their OH and D/H systematics. Apatites in high-Ti basaltic samples display a relatively restricted range in OH contents (~1500-3000ppm) with large δD variations (~600-1000 ‰) whereas apatites in low-Ti Apollo basalts and lunar meteorites display a comparatively larger range in OH contents (~500-15000ppm), each sample displaying relatively restricted variations in their D/H ratios. Analyses of apatites in basaltic meteorites Miller Range 05035 and LaPaz Icefield 04841 substantially expand the lower bound for δD values measured in apatites from Apollo mare basalts, down to δD values of ~100‰. In these meteorites, high resolution mapping of the distribution of secondary ions of H and C was used to avoid cracks and hotspots. Together with mixing calculations for terrestrial contamination, this analytical protocol ensured that most of the values reported for MIL 05035 and LAP 04841 correspond to their actual lunar signatures. We interpret the large variations of apatite δD values in mare basalts between ~200‰ and 1000‰ as a result of different amounts of degassing of H-bearing species initially dissolved in the basaltic parental melts. Indeed, the average δD values measured in different low-Ti basalts are consistent with ~85-99% degassing of H as H 2, starting from a δD value of 100‰. Degassing of H-bearing species essentially as H 2 was favoured by the reduced nature of lunar magmas. In low-Ti mare basalts, apatite crystallisation occurred after degassing of the H-bearing species and the OH variations reflect different degrees of fractional crystallisation. In high-Ti mare basalts, large δD variations with relatively restricted range in OH contents imply that apatite crystallisation and degassing of H-bearing species were mostly coeval. Geochemical modelling integrating corrections for degassing and fractional crystallisation suggests that the mantle source regions of the different low-Ti mare basalts could have contained ~5-50ppm H (equivalent to ~45-450ppm H 2 O), which are similar to the estimated range of ~60-350ppm water for the Earth's upper mantle. Finally, the H isotopic composition of pre-degassed lunar hydrogen in mare basalts is consistent with a CI-chondrite-type value of ~100‰, which is consistent with the increasing evidence suggesting that the Earth, Mars and the Moon might have accreted similar water of chondritic origin.

@article{doi101016jgca201308014,
    author = "Tartèse, Romain and Anand, M. and Barnes, Jessica and Starkey, N. A. and Franchi, I. A. and Sano, Yuji",
    title = "The abundance, distribution, and isotopic composition of Hydrogen in the Moon as revealed by basaltic lunar samples: Implications for the volatile inventory of the Moon",
    year = "2013",
    journal = "Geochimica et Cosmochimica Acta",
    abstract = "In this study we have measured the OH contents and D/H ratios in apatite grains in lunar basalts. These new data considerably expand the limited dataset published so far. The data presented in this study also show that there is a major difference between high- and low-Ti mare basalts in terms of their OH and D/H systematics. Apatites in high-Ti basaltic samples display a relatively restricted range in OH contents (\textasciitilde 1500-3000ppm) with large δD variations (\textasciitilde 600-1000 ‰) whereas apatites in low-Ti Apollo basalts and lunar meteorites display a comparatively larger range in OH contents (\textasciitilde 500-15000ppm), each sample displaying relatively restricted variations in their D/H ratios. Analyses of apatites in basaltic meteorites Miller Range 05035 and LaPaz Icefield 04841 substantially expand the lower bound for δD values measured in apatites from Apollo mare basalts, down to δD values of \textasciitilde 100‰. In these meteorites, high resolution mapping of the distribution of secondary ions of H and C was used to avoid cracks and hotspots. Together with mixing calculations for terrestrial contamination, this analytical protocol ensured that most of the values reported for MIL 05035 and LAP 04841 correspond to their actual lunar signatures. We interpret the large variations of apatite δD values in mare basalts between \textasciitilde 200‰ and 1000‰ as a result of different amounts of degassing of H-bearing species initially dissolved in the basaltic parental melts. Indeed, the average δD values measured in different low-Ti basalts are consistent with \textasciitilde 85-99\% degassing of H as H 2, starting from a δD value of 100‰. Degassing of H-bearing species essentially as H 2 was favoured by the reduced nature of lunar magmas. In low-Ti mare basalts, apatite crystallisation occurred after degassing of the H-bearing species and the OH variations reflect different degrees of fractional crystallisation. In high-Ti mare basalts, large δD variations with relatively restricted range in OH contents imply that apatite crystallisation and degassing of H-bearing species were mostly coeval. Geochemical modelling integrating corrections for degassing and fractional crystallisation suggests that the mantle source regions of the different low-Ti mare basalts could have contained \textasciitilde 5-50ppm H (equivalent to \textasciitilde 45-450ppm H 2 O), which are similar to the estimated range of \textasciitilde 60-350ppm water for the Earth's upper mantle. Finally, the H isotopic composition of pre-degassed lunar hydrogen in mare basalts is consistent with a CI-chondrite-type value of \textasciitilde 100‰, which is consistent with the increasing evidence suggesting that the Earth, Mars and the Moon might have accreted similar water of chondritic origin.",
    url = "https://doi.org/10.1016/j.gca.2013.08.014",
    doi = "10.1016/j.gca.2013.08.014",
    openalex = "W2100553768",
    references = "doi101126science1235142"
}

Water is perhaps the most important molecule in the solar system, and determining its origin and distribution in planetary interiors has important implications for understanding the evolution of planetary bodies. Here we report in situ measurements of the isotopic composition of hydrogen dissolved in primitive volcanic glass and olivine-hosted melt inclusions recovered from the Moon by the Apollo 15 and 17 missions. After consideration of cosmic-ray spallation and degassing processes, our results demonstrate that lunar magmatic water has an isotopic composition that is indistinguishable from that of the bulk water in carbonaceous chondrites and similar to that of terrestrial water, implying a common origin for the water contained in the interiors of Earth and the Moon.

@article{doi101126science1235142,
    author = "Saal, A. E. and Hauri, E. H. and Orman, James A. Van and Rutherford, M. J.",
    title = "Hydrogen Isotopes in Lunar Volcanic Glasses and Melt Inclusions Reveal a Carbonaceous Chondrite Heritage",
    year = "2013",
    journal = "Science",
    abstract = "Water is perhaps the most important molecule in the solar system, and determining its origin and distribution in planetary interiors has important implications for understanding the evolution of planetary bodies. Here we report in situ measurements of the isotopic composition of hydrogen dissolved in primitive volcanic glass and olivine-hosted melt inclusions recovered from the Moon by the Apollo 15 and 17 missions. After consideration of cosmic-ray spallation and degassing processes, our results demonstrate that lunar magmatic water has an isotopic composition that is indistinguishable from that of the bulk water in carbonaceous chondrites and similar to that of terrestrial water, implying a common origin for the water contained in the interiors of Earth and the Moon.",
    url = "https://doi.org/10.1126/science.1235142",
    doi = "10.1126/science.1235142",
    openalex = "W2156921334",
    references = "doi101016jepsl201110040, doi101016jgca200706052, doi101038nature07047, doi101107s0567739476001551, doi101111j194551002000tb01518x, doi101126science1178658, doi101126science1186986, doi101126science1223474, doi101126science1225542, doi101126science1226073"
}

High-resolution gravity data from the Gravity Recovery and Interior Laboratory spacecraft have clarified the origin of lunar mass concentrations (mascons). Free-air gravity anomalies over lunar impact basins display bull's-eye patterns consisting of a central positive (mascon) anomaly, a surrounding negative collar, and a positive outer annulus. We show that this pattern results from impact basin excavation and collapse followed by isostatic adjustment and cooling and contraction of a voluminous melt pool. We used a hydrocode to simulate the impact and a self-consistent finite-element model to simulate the subsequent viscoelastic relaxation and cooling. The primary parameters controlling the modeled gravity signatures of mascon basins are the impactor energy, the lunar thermal gradient at the time of impact, the crustal thickness, and the extent of volcanic fill.

@article{doi101126science1235768,
    author = "Melosh, H. J. and Freed, A. M. and Johnson, Brandon and Blair, D. M. and Andrews‐Hanna, J. C. and Neumann, G. A. and Phillips, R. J. and Smith, David E. and Solomon, Sean C. and Wieczorek, M. A. and Zuber, M. T.",
    title = "The Origin of Lunar Mascon Basins",
    year = "2013",
    journal = "Science",
    abstract = "High-resolution gravity data from the Gravity Recovery and Interior Laboratory spacecraft have clarified the origin of lunar mass concentrations (mascons). Free-air gravity anomalies over lunar impact basins display bull's-eye patterns consisting of a central positive (mascon) anomaly, a surrounding negative collar, and a positive outer annulus. We show that this pattern results from impact basin excavation and collapse followed by isostatic adjustment and cooling and contraction of a voluminous melt pool. We used a hydrocode to simulate the impact and a self-consistent finite-element model to simulate the subsequent viscoelastic relaxation and cooling. The primary parameters controlling the modeled gravity signatures of mascon basins are the impactor energy, the lunar thermal gradient at the time of impact, the crustal thickness, and the extent of volcanic fill.",
    url = "https://doi.org/10.1126/science.1235768",
    doi = "10.1126/science.1235768",
    openalex = "W2072306887",
    references = "doi1010160019103589901292, doi101016jicarus200510013, doi101017cbo9780511612879, doi1010292005je002608, doi1010292010gl043751, doi101093petrology293625, doi101111j194551002004tb00337x, doi101126science1231507, doi101126science1231530, doi101126science1613842680, doi101126science26651921839, khan2006are, openalexw2990054233"
}

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 TiO2 relative to the surrounding mantle. The melt phase is neutrally buoyant at pressures of ∼4.5–4.6 GPa but contains less TiO2 (<15 wt %) than the Ti-rich (∼16 wt %) melts that produced a set of high-density primitive lunar magmas (density of 3.4 g/cm3). Melt densities computed here range from 3.25 to 3.45 g/cm3 bracketing the density of lunar magmas with moderate-to-high TiO2 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.

@article{doi1010022014je004661,
    author = "Khan, A. and Connolly, J. A. D. and Pommier, Anne and Noir, Jérõme",
    title = "Geophysical evidence for melt in the deep lunar interior and implications for lunar evolution",
    year = "2014",
    journal = "Journal of Geophysical Research Planets",
    abstract = "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 TiO2 relative to the surrounding mantle. The melt phase is neutrally buoyant at pressures of ∼4.5–4.6 GPa but contains less TiO2 (<15 wt \%) than the Ti-rich (∼16 wt \%) melts that produced a set of high-density primitive lunar magmas (density of 3.4 g/cm3). Melt densities computed here range from 3.25 to 3.45 g/cm3 bracketing the density of lunar magmas with moderate-to-high TiO2 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.",
    url = "https://doi.org/10.1002/2014je004661",
    doi = "10.1002/2014je004661",
    openalex = "W2148289691",
    references = "doi1010292005je002608, khan2006are"
}

The recent discoveries of hydrogen (H) bearing species on the lunar surface and in samples derived from the lunar interior have necessitated a paradigm shift in our understanding of the water inventory of the Moon, which was previously considered to be a ‘bone-dry’ planetary body. Most sample-based studies have focused on assessing the water contents of the younger mare basalts and pyroclastic glasses, which are partial-melting products of the lunar mantle. In contrast, little attention has been paid to the inventory and source(s) of water in the lunar highlands rocks which are some of the oldest and most pristine materials available for laboratory investigations, and that have the potential to reveal the original history of water in the Earth–Moon system. Here, we report in-situ measurements of hydroxyl (OH) content and H isotopic composition of the mineral apatite from four lunar highlands samples (two norites, a troctolite, and a granite clast) collected during the Apollo missions. Apart from troctolite in which the measured OH contents in apatite are close to our analytical detection limit and its H isotopic composition appears to be severely compromised by secondary processes, we have measured up to ∼2200ppm OH in the granite clast with a weighted average δD of ∼−105±130‰, and up to ∼3400ppm OH in the two norites (77215 and 78235) with weighted average δD values of −281±49‰ and −27±98‰, respectively. The apatites in the granite clast and the norites are characterised by higher OH contents than have been reported so far for highlands samples, and have H isotopic compositions similar to those of terrestrial materials and some carbonaceous chondrites, providing one of the strongest pieces of evidence yet for a common origin for water in the Earth–Moon system. In addition, the presence of water, of terrestrial affinity, in some samples of the earliest-formed lunar crust suggests that either primordial terrestrial water survived the aftermath of the putative impact-origin of the Moon or water was added to the Earth–Moon system by a common source immediately after the accretion of the Moon.

@article{doi101016jepsl201401015,
    author = "Barnes, Jessica and Tartèse, Romain and Anand, M. and McCubbin, F. M. and Franchi, I. A. and Starkey, N. A. and Russell, S. S.",
    title = "The origin of water in the primitive Moon as revealed by the lunar highlands samples",
    year = "2014",
    journal = "Earth and Planetary Science Letters",
    abstract = "The recent discoveries of hydrogen (H) bearing species on the lunar surface and in samples derived from the lunar interior have necessitated a paradigm shift in our understanding of the water inventory of the Moon, which was previously considered to be a ‘bone-dry’ planetary body. Most sample-based studies have focused on assessing the water contents of the younger mare basalts and pyroclastic glasses, which are partial-melting products of the lunar mantle. In contrast, little attention has been paid to the inventory and source(s) of water in the lunar highlands rocks which are some of the oldest and most pristine materials available for laboratory investigations, and that have the potential to reveal the original history of water in the Earth–Moon system. Here, we report in-situ measurements of hydroxyl (OH) content and H isotopic composition of the mineral apatite from four lunar highlands samples (two norites, a troctolite, and a granite clast) collected during the Apollo missions. Apart from troctolite in which the measured OH contents in apatite are close to our analytical detection limit and its H isotopic composition appears to be severely compromised by secondary processes, we have measured up to ∼2200ppm OH in the granite clast with a weighted average δD of ∼−105±130‰, and up to ∼3400ppm OH in the two norites (77215 and 78235) with weighted average δD values of −281±49‰ and −27±98‰, respectively. The apatites in the granite clast and the norites are characterised by higher OH contents than have been reported so far for highlands samples, and have H isotopic compositions similar to those of terrestrial materials and some carbonaceous chondrites, providing one of the strongest pieces of evidence yet for a common origin for water in the Earth–Moon system. In addition, the presence of water, of terrestrial affinity, in some samples of the earliest-formed lunar crust suggests that either primordial terrestrial water survived the aftermath of the putative impact-origin of the Moon or water was added to the Earth–Moon system by a common source immediately after the accretion of the Moon.",
    url = "https://doi.org/10.1016/j.epsl.2014.01.015",
    doi = "10.1016/j.epsl.2014.01.015",
    openalex = "W2094508362",
    references = "doi101016jgca201102033"
}

Geochemical data for H2O and other volatiles, as well as major and trace elements, are reported for 377 samples of lunar volcanic glass from three chemical groups (A15 green, A15 yellow, A17 orange 74 220). These data demonstrate that degassing is a pervasive process that has affected all extrusive lunar rocks. The data are combined with published data to estimate the total composition of the bulk silicate Moon (BSM). The estimated BSM composition for highly volatile elements, constrained by H2O/Ce ratios and S contents in melt inclusions from orange glass sample 74 220, are only moderately depleted compared with the bulk silicate Earth (avg. 0.25X BSE) and essentially overlap the composition of the terrestrial depleted MORB source. In a single giant impact origin for the Moon, the Moon-forming material experiences three stages of evolution characterized by very different timescales. Impact mass ejection and proto-lunar disk evolution both permit system loss of H2O and other volatiles on timescales ranging from days to centuries; the early Moon is likely to have accreted from a thin magma disk of limited volume embedded in, but largely displaced from, the extended distribution of vapor around the Earth. Only the protracted evolution of the lunar magma ocean (LMO) presents a time window sufficiently long (10–200 Ma) for the Moon to gain water during the tail end of accretion. This “hot start” to lunar formation is however not the only model that matches the lunar volatile abundances; a “cold start” in which the proto-lunar disk is largely composed of solid material could result in efficient delivery of terrestrial water to the Moon, while a “warm start” producing a disk of 25% volatile-retentive solids and 75% volatile-depleted magma/vapor is also consistent with the data. At the same time, there exists little evidence that the Moon formed in a singular event, as all detailed planetary accretion models predict several giant impacts in the terrestrial planet region in which the Earth forms. It is thus conceivable that the Moon, like the Earth, experienced a history of heterogeneous accretion.

@article{doi101016jepsl201410053,
    author = "Hauri, E. H. and Saal, A. E. and Rutherford, M. J. and Orman, James A. Van",
    title = "Water in the Moon's interior: Truth and consequences",
    year = "2014",
    journal = "Earth and Planetary Science Letters",
    abstract = "Geochemical data for H2O and other volatiles, as well as major and trace elements, are reported for 377 samples of lunar volcanic glass from three chemical groups (A15 green, A15 yellow, A17 orange 74 220). These data demonstrate that degassing is a pervasive process that has affected all extrusive lunar rocks. The data are combined with published data to estimate the total composition of the bulk silicate Moon (BSM). The estimated BSM composition for highly volatile elements, constrained by H2O/Ce ratios and S contents in melt inclusions from orange glass sample 74 220, are only moderately depleted compared with the bulk silicate Earth (avg. 0.25X BSE) and essentially overlap the composition of the terrestrial depleted MORB source. In a single giant impact origin for the Moon, the Moon-forming material experiences three stages of evolution characterized by very different timescales. Impact mass ejection and proto-lunar disk evolution both permit system loss of H2O and other volatiles on timescales ranging from days to centuries; the early Moon is likely to have accreted from a thin magma disk of limited volume embedded in, but largely displaced from, the extended distribution of vapor around the Earth. Only the protracted evolution of the lunar magma ocean (LMO) presents a time window sufficiently long (10–200 Ma) for the Moon to gain water during the tail end of accretion. This “hot start” to lunar formation is however not the only model that matches the lunar volatile abundances; a “cold start” in which the proto-lunar disk is largely composed of solid material could result in efficient delivery of terrestrial water to the Moon, while a “warm start” producing a disk of 25\% volatile-retentive solids and 75\% volatile-depleted magma/vapor is also consistent with the data. At the same time, there exists little evidence that the Moon formed in a singular event, as all detailed planetary accretion models predict several giant impacts in the terrestrial planet region in which the Earth forms. It is thus conceivable that the Moon, like the Earth, experienced a history of heterogeneous accretion.",
    url = "https://doi.org/10.1016/j.epsl.2014.10.053",
    doi = "10.1016/j.epsl.2014.10.053",
    openalex = "W2091767579",
    references = "doi101007bf00307281, doi1010160009254194001404, doi101016jepsl201110040, doi1010292012gc004334, doi10103835089010, doi101038nature03676, doi101086375492, doi101098rsta19880066, doi101111j194551002000tb01518x, doi101126science1231507, doi101126science1231530, doi101126science1235142"
}

Geochemical evidence suggests that the material accreted by the Earth did not change in nature during Earth's accretion, presumably because the inner protoplanetary disc had uniform isotopic composition similar to enstatite chondrites, aubrites and ungrouped achondrite NWA 5363/5400. Enstatite meteorites and the Earth were derived from the same nebular reservoir but diverged in their chemical evolutions, so no chondrite sample in meteorite collections is representative of the Earth's building blocks. The similarity in isotopic composition (Δ(17)O, ε(50)Ti and ε(54)Cr) between lunar and terrestrial rocks is explained by the fact that the Moon-forming impactor came from the same region of the disc as other Earth-forming embryos, and therefore was similar in isotopic composition to the Earth. The heavy δ(30)Si values of the silicate Earth and the Moon relative to known chondrites may be due to fractionation in the solar nebula/protoplanetary disc rather than partitioning of silicon in Earth's core. An inversion method is presented to calculate the Hf/W ratios and ε(182)W values of the proto-Earth and impactor mantles for a given Moon-forming impact scenario. The similarity in tungsten isotopic composition between lunar and terrestrial rocks is a coincidence that can be explained in a canonical giant impact scenario if an early formed embryo (two-stage model age of 10-20 Myr) collided with the proto-Earth formed over a more protracted accretion history (two-stage model age of 30-40 Myr).

@article{doi101098rsta20130244,
    author = "Dauphas, Nicolas and Burkhardt, Christoph and Warren, P. H. and Teng, Fang‐Zhen",
    title = "Geochemical arguments for an Earth-like Moon-forming impactor",
    year = "2014",
    journal = "Philosophical Transactions of the Royal Society A Mathematical Physical and Engineering Sciences",
    abstract = "Geochemical evidence suggests that the material accreted by the Earth did not change in nature during Earth's accretion, presumably because the inner protoplanetary disc had uniform isotopic composition similar to enstatite chondrites, aubrites and ungrouped achondrite NWA 5363/5400. Enstatite meteorites and the Earth were derived from the same nebular reservoir but diverged in their chemical evolutions, so no chondrite sample in meteorite collections is representative of the Earth's building blocks. The similarity in isotopic composition (Δ(17)O, ε(50)Ti and ε(54)Cr) between lunar and terrestrial rocks is explained by the fact that the Moon-forming impactor came from the same region of the disc as other Earth-forming embryos, and therefore was similar in isotopic composition to the Earth. The heavy δ(30)Si values of the silicate Earth and the Moon relative to known chondrites may be due to fractionation in the solar nebula/protoplanetary disc rather than partitioning of silicon in Earth's core. An inversion method is presented to calculate the Hf/W ratios and ε(182)W values of the proto-Earth and impactor mantles for a given Moon-forming impact scenario. The similarity in tungsten isotopic composition between lunar and terrestrial rocks is a coincidence that can be explained in a canonical giant impact scenario if an early formed embryo (two-stage model age of 10-20 Myr) collided with the proto-Earth formed over a more protracted accretion history (two-stage model age of 30-40 Myr).",
    url = "https://doi.org/10.1098/rsta.2013.0244",
    doi = "10.1098/rsta.2013.0244",
    openalex = "W2097645720",
    references = "doi101016jgca200606262, doi1010292005je002608, khan2006are"
}

The lunar geological record contains a rich archive of the history of the inner Solar System, including information relevant to understanding the origin and evolution of the Earth-Moon system, the geological evolution of rocky planets, and our local cosmic environment. This paper provides a brief review of lunar exploration to-date and describes how future exploration initiatives will further advance our understanding of the origin and evolution of the Moon, the Earth-Moon system and of the Solar System more generally. It is concluded that further advances will require the placing of new scientific instruments on, and the return of additional samples from, the lunar surface. Some of these scientific objectives can be achieved robotically, for example by in situ geochemical and geophysical measurements and through carefully targeted sample return missions. However, in the longer term, we argue that lunar science would greatly benefit from renewed human operations on the surface of the Moon, such as would be facilitated by implementing the recently proposed Global Exploration Roadmap.

@article{doi101098rsta20130315,
    author = "Crawford, Ian and Joy, K. H.",
    title = "Lunar exploration: opening a window into the history and evolution of the inner Solar System",
    year = "2014",
    journal = "Philosophical Transactions of the Royal Society A Mathematical Physical and Engineering Sciences",
    abstract = "The lunar geological record contains a rich archive of the history of the inner Solar System, including information relevant to understanding the origin and evolution of the Earth-Moon system, the geological evolution of rocky planets, and our local cosmic environment. This paper provides a brief review of lunar exploration to-date and describes how future exploration initiatives will further advance our understanding of the origin and evolution of the Moon, the Earth-Moon system and of the Solar System more generally. It is concluded that further advances will require the placing of new scientific instruments on, and the return of additional samples from, the lunar surface. Some of these scientific objectives can be achieved robotically, for example by in situ geochemical and geophysical measurements and through carefully targeted sample return missions. However, in the longer term, we argue that lunar science would greatly benefit from renewed human operations on the surface of the Moon, such as would be facilitated by implementing the recently proposed Global Exploration Roadmap.",
    url = "https://doi.org/10.1098/rsta.2013.0315",
    doi = "10.1098/rsta.2013.0315",
    openalex = "W2000349148",
    references = "doi1010160009254194001404, doi1010160016703789901506, doi101016b9780080959757002011, doi101017cbo9780511545986, doi1010291999je001103, doi101038355125a0, doi101038nature03676, doi101126science1186986, doi101126science1231530, openalexw2139291338"
}

The Mg-suite represents an enigmatic episode of lunar highlands magmatism that presumably represents the first stage of crustal building following primordial differentiation. This review examines the mineralogy, geochemistry, petrology, chronology, and the planetary-scale distribution of this suite of highlands plutonic rocks, presents models for their origin, examines petrogenetic relationships to other highlands rocks, and explores the link between this style of magmatism and early stages of lunar differentiation. Of the models considered for the origin of the parent magmas for the Mg-suite, the data best fit a process in which hot (solidus temperature at ≥2 GPa = 1600 to 1800 °C) and less dense (r ~3100 kg/m3) early lunar magma ocean cumulates rise to the base of the crust during cumulate pile overturn. Some decompressional melting would occur, but placing a hot cumulate horizon adjacent to the plagioclase-rich primordial crust and KREEP-rich lithologies (at temperatures of <1300 °C) would result in the hybridization of these divergent primordial lithologies, producing Mg-suite parent magmas. As urKREEP (primeval KREEP) is not the “petrologic driver” of this style of magmatism, outside of the Procellarum KREEP Terrane (PKT), Mg-suite magmas are not required to have a KREEP signature. Evaluation of the chronology of this episode of highlands evolution indicates that Mg-suite magmatism was initiated soon after primordial differentiation (<10 m.y.). Alternatively, the thermal event associated with the mantle overturn may have disrupted the chronometers utilized to date the primordial crust. Petrogenetic relationships between the Mg-suite and other highlands suites (e.g., alkali-suite and magnesian anorthositic granulites) are consistent with both fractional crystallization processes and melting of distinctly different hybrid sources.

@article{doi102138am20154817,
    author = "Shearer, C. K. and Elardo, S. M. and Petro, N. E. and Borg, L. E. and McCubbin, F. M.",
    title = "Origin of the lunar highlands Mg-suite: An integrated petrology, geochemistry, chronology, and remote sensing perspective",
    year = "2014",
    journal = "American Mineralogist",
    abstract = "The Mg-suite represents an enigmatic episode of lunar highlands magmatism that presumably represents the first stage of crustal building following primordial differentiation. This review examines the mineralogy, geochemistry, petrology, chronology, and the planetary-scale distribution of this suite of highlands plutonic rocks, presents models for their origin, examines petrogenetic relationships to other highlands rocks, and explores the link between this style of magmatism and early stages of lunar differentiation. Of the models considered for the origin of the parent magmas for the Mg-suite, the data best fit a process in which hot (solidus temperature at ≥2 GPa = 1600 to 1800 °C) and less dense (r \textasciitilde 3100 kg/m3) early lunar magma ocean cumulates rise to the base of the crust during cumulate pile overturn. Some decompressional melting would occur, but placing a hot cumulate horizon adjacent to the plagioclase-rich primordial crust and KREEP-rich lithologies (at temperatures of <1300 °C) would result in the hybridization of these divergent primordial lithologies, producing Mg-suite parent magmas. As urKREEP (primeval KREEP) is not the “petrologic driver” of this style of magmatism, outside of the Procellarum KREEP Terrane (PKT), Mg-suite magmas are not required to have a KREEP signature. Evaluation of the chronology of this episode of highlands evolution indicates that Mg-suite magmatism was initiated soon after primordial differentiation (<10 m.y.). Alternatively, the thermal event associated with the mantle overturn may have disrupted the chronometers utilized to date the primordial crust. Petrogenetic relationships between the Mg-suite and other highlands suites (e.g., alkali-suite and magnesian anorthositic granulites) are consistent with both fractional crystallization processes and melting of distinctly different hybrid sources.",
    url = "https://doi.org/10.2138/am-2015-4817",
    doi = "10.2138/am-2015-4817",
    openalex = "W2117913256",
    references = "doi101016jgca201102033"
}

Low estimated lunar volatile contents, compared with Earth, are a fundamental observation for Earth-Moon system formation and lunar evolution. Here we present zinc isotope and abundance data for lunar crustal rocks to constrain the abundance of volatiles during the final stages of lunar differentiation. We find that ferroan anorthosites are isotopically heterogeneous, with some samples exhibiting high δ(66)Zn, along with alkali and magnesian suite samples. Since the plutonic samples were formed in the lunar crust, they were not subjected to degassing into vacuum. Instead, their compositions are consistent with enrichment of the silicate portions of the Moon in the heavier Zn isotopes. Because of the difference in δ(66)Zn between bulk silicate Earth and lunar basalts and crustal rocks, the volatile loss likely occurred in two stages: during the proto-lunar disk stage, where a fraction of lunar volatiles accreted onto Earth, and from degassing of a differentiating lunar magma ocean, implying the possibility of isolated, volatile-rich regions in the Moon's interior.

@article{doi101038ncomms8617,
    author = "Kato, Chizu and Moynier, Frédéric and Valdes, Maria C. and Dhaliwal, Jasmeet K. and Day, James M.D.",
    title = "Extensive volatile loss during formation and differentiation of the Moon",
    year = "2015",
    journal = "Nature Communications",
    abstract = "Low estimated lunar volatile contents, compared with Earth, are a fundamental observation for Earth-Moon system formation and lunar evolution. Here we present zinc isotope and abundance data for lunar crustal rocks to constrain the abundance of volatiles during the final stages of lunar differentiation. We find that ferroan anorthosites are isotopically heterogeneous, with some samples exhibiting high δ(66)Zn, along with alkali and magnesian suite samples. Since the plutonic samples were formed in the lunar crust, they were not subjected to degassing into vacuum. Instead, their compositions are consistent with enrichment of the silicate portions of the Moon in the heavier Zn isotopes. Because of the difference in δ(66)Zn between bulk silicate Earth and lunar basalts and crustal rocks, the volatile loss likely occurred in two stages: during the proto-lunar disk stage, where a fraction of lunar volatiles accreted onto Earth, and from degassing of a differentiating lunar magma ocean, implying the possibility of isolated, volatile-rich regions in the Moon's interior.",
    url = "https://doi.org/10.1038/ncomms8617",
    doi = "10.1038/ncomms8617",
    openalex = "W1882246603",
    references = "doi1010160019103589901292, doi101016jepsl200404032, doi101016jepsl201302037, doi101016jepsl201410053, doi101038nature07047, doi101038nature08477, doi101038nature11507, doi101073pnas1006677107, doi101086375492, doi101126science1235142, doi102138rmg2006604, openalexw1680065073"
}

Many studies exist on magmatic volatiles (H, C, N, F, S, Cl) in and on the Moon, within the last several years, that have cast into question the post-Apollo view of lunar formation, the distribution and sources of volatiles in the Earth-Moon system, and the thermal and magmatic evolution of the Moon. However, these recent observations are not the first data on lunar volatiles. When Apollo samples were first returned, substantial efforts were made to understand volatile elements, and a wealth of data regarding volatile elements exists in this older literature. In this review paper, we approach volatiles in and on the Moon using new and old data derived from lunar samples and remote sensing. From combining these data sets, we identified many points of convergence, although numerous questions remain unanswered.

@article{doi102138am20154934ccbyncnd,
    author = "McCubbin, F. M. and Kaaden, K. E. Vander and Tartèse, Romain and Klima, R. L. and Liu, Yang and Mortimer, James and Barnes, Jessica and Shearer, C. K. and Treiman, A. H. and Lawrence, D. J. and Elardo, S. M. and Hurley, D. M. and Boyce, J. W. and Anand, M.",
    title = "Magmatic volatiles (H, C, N, F, S, Cl) in the lunar mantle, crust, and regolith: Abundances, distributions, processes, and reservoirs",
    year = "2015",
    journal = "American Mineralogist",
    abstract = "Many studies exist on magmatic volatiles (H, C, N, F, S, Cl) in and on the Moon, within the last several years, that have cast into question the post-Apollo view of lunar formation, the distribution and sources of volatiles in the Earth-Moon system, and the thermal and magmatic evolution of the Moon. However, these recent observations are not the first data on lunar volatiles. When Apollo samples were first returned, substantial efforts were made to understand volatile elements, and a wealth of data regarding volatile elements exists in this older literature. In this review paper, we approach volatiles in and on the Moon using new and old data derived from lunar samples and remote sensing. From combining these data sets, we identified many points of convergence, although numerous questions remain unanswered.",
    url = "https://doi.org/10.2138/am-2015-4934ccbyncnd",
    doi = "10.2138/am-2015-4934ccbyncnd",
    openalex = "W2136572031",
    references = "doi101007bf03024549, doi1010160045873287900076, doi101016jepsl201110040, doi101016jepsl201410053, doi101016jgca200606262, doi101016jgca201102033, doi1010291999je001103, doi1010292005jd006338, doi101038269209a0, doi101086375492, doi101126science1186986, doi101126science1231530, doi101126science1235142, doi101126science25550501391"
}

@article{doi101016jearscirev201607007,
    author = "Stüeken, Eva E. and Kipp, Michael A. and Koehler, Matthew C. and Buick, Roger",
    title = "The evolution of Earth's biogeochemical nitrogen cycle",
    year = "2016",
    journal = "Earth-Science Reviews",
    url = "https://doi.org/10.1016/j.earscirev.2016.07.007",
    doi = "10.1016/j.earscirev.2016.07.007",
    openalex = "W2492459478",
    references = "doi101016jepsl201110040, doi101016jgca201306002, doi101016jgca201502025, doi101016jgca201610050, doi101016jprecamres201206018, doi101016jprecamres201411030, doi101038nature11445, doi101126science1258410, doi101146annurevearth33031504103001"
}

Current models for the Moon's formation have yet to fully account for the thermal evolution of the Moon in the presence of H2O and other volatiles. Of particular importance is chlorine, since most lunar samples are characterised by unique heavy δ37Cl values, significantly deviating from those of other planetary materials, including Earth, for which δ37Cl values cluster around ∼0‰. In order to unravel the cause(s) of the Moon's unique chlorine isotope signature, we performed a comprehensive study of high-precision in situ Cl isotope measurements of apatite from a suite of Apollo samples with a range of geochemical characteristics and petrologic types. The Cl-isotopic compositions measured in lunar apatite in the studied samples display a wide range of δ37Cl values (reaching a maximum value of +36‰), which are positively correlated with the amount of potassium (K), Rare Earth Element (REE) and phosphorous (P) (KREEP) component in each sample. Using these new data, integrated with existing H-isotope data obtained for the same samples, we are able to place these findings in the context of the canonical lunar magma ocean (LMO) model. The results are consistent with the urKREEP reservoir being characterised by a δ37Cl ∼+30‰. Such a heavy Cl isotope signature requires metal-chloride degassing from a Cl-enriched urKREEP LMO residue, a process likely to have been triggered by at least one large crust-breaching impact event that facilitated the transport and exposure of urKREEP liquid to the lunar surface.

@article{doi101016jepsl201604036,
    author = "Barnes, Jessica J. and Tartèse, Romain and Anand, M. and McCubbin, F. M. and Neal, C. R. and Franchi, I. A.",
    title = "Early degassing of lunar urKREEP by crust-breaching impact(s)",
    year = "2016",
    journal = "Earth and Planetary Science Letters",
    abstract = "Current models for the Moon's formation have yet to fully account for the thermal evolution of the Moon in the presence of H2O and other volatiles. Of particular importance is chlorine, since most lunar samples are characterised by unique heavy δ37Cl values, significantly deviating from those of other planetary materials, including Earth, for which δ37Cl values cluster around ∼0‰. In order to unravel the cause(s) of the Moon's unique chlorine isotope signature, we performed a comprehensive study of high-precision in situ Cl isotope measurements of apatite from a suite of Apollo samples with a range of geochemical characteristics and petrologic types. The Cl-isotopic compositions measured in lunar apatite in the studied samples display a wide range of δ37Cl values (reaching a maximum value of +36‰), which are positively correlated with the amount of potassium (K), Rare Earth Element (REE) and phosphorous (P) (KREEP) component in each sample. Using these new data, integrated with existing H-isotope data obtained for the same samples, we are able to place these findings in the context of the canonical lunar magma ocean (LMO) model. The results are consistent with the urKREEP reservoir being characterised by a δ37Cl ∼+30‰. Such a heavy Cl isotope signature requires metal-chloride degassing from a Cl-enriched urKREEP LMO residue, a process likely to have been triggered by at least one large crust-breaching impact event that facilitated the transport and exposure of urKREEP liquid to the lunar surface.",
    url = "https://doi.org/10.1016/j.epsl.2016.04.036",
    doi = "10.1016/j.epsl.2016.04.036",
    openalex = "W2393197622",
    references = "doi101038ncomms8617, doi101111maps12647, doi102138am20154934ccbyncnd"
}

@article{doi101038nature19341,
    author = "Wang, Kun and Jacobsen, S. B.",
    title = "Potassium isotopic evidence for a high-energy giant impact origin of the Moon",
    year = "2016",
    journal = "Nature",
    url = "https://doi.org/10.1038/nature19341",
    doi = "10.1038/nature19341",
    openalex = "W2508931438",
    references = "doi101038ncomms8617"
}

The Apollo-derived tenet of an anhydrous Moon has been contested following measurement of water in several lunar samples that require water to be present in the lunar interior. However, significant uncertainties exist regarding the flux, sources and timing of water delivery to the Moon. Here we address those fundamental issues by constraining the mass of water accreted to the Moon and modelling the relative proportions of asteroidal and cometary sources for water that are consistent with measured isotopic compositions of lunar samples. We determine that a combination of carbonaceous chondrite-type materials were responsible for the majority of water (and nitrogen) delivered to the Earth-Moon system. Crucially, we conclude that comets containing water enriched in deuterium contributed significantly <20% of the water in the Moon. Therefore, our work places important constraints on the types of objects impacting the Moon ∼4.5-4.3 billion years ago and on the origin of water in the inner Solar System.

@article{doi101038ncomms11684,
    author = "Barnes, Jessica and Kring, D. A. and Tartèse, Romain and Franchi, I. A. and Anand, M. and Russell, S. S.",
    title = "An asteroidal origin for water in the Moon",
    year = "2016",
    journal = "Nature Communications",
    abstract = "The Apollo-derived tenet of an anhydrous Moon has been contested following measurement of water in several lunar samples that require water to be present in the lunar interior. However, significant uncertainties exist regarding the flux, sources and timing of water delivery to the Moon. Here we address those fundamental issues by constraining the mass of water accreted to the Moon and modelling the relative proportions of asteroidal and cometary sources for water that are consistent with measured isotopic compositions of lunar samples. We determine that a combination of carbonaceous chondrite-type materials were responsible for the majority of water (and nitrogen) delivered to the Earth-Moon system. Crucially, we conclude that comets containing water enriched in deuterium contributed significantly <20\% of the water in the Moon. Therefore, our work places important constraints on the types of objects impacting the Moon ∼4.5-4.3 billion years ago and on the origin of water in the inner Solar System.",
    url = "https://doi.org/10.1038/ncomms11684",
    doi = "10.1038/ncomms11684",
    openalex = "W2410907776",
    references = "doi102138am20154934ccbyncnd"
}

@article{doi101007s112140170387z,
    author = "Peslier, A. H. and Schönbächler, Maria and Busemann, H. and Karato, Shun‐ichiro",
    title = "Water in the Earth’s Interior: Distribution and Origin",
    year = "2017",
    journal = "Space Science Reviews",
    url = "https://doi.org/10.1007/s11214-017-0387-z",
    doi = "10.1007/s11214-017-0387-z",
    openalex = "W2743347859",
    references = "doi1010160031920181900467, doi1010160031920186900932, doi101016c20091284735, doi101016jepsl201410053, doi101016s0009254197001502, doi1010292008je003126, doi101086375492, doi101098rsta20150390, doi101126science1235142, doi101126science28053671245, doi101144gslsp19890420119, doi101146annurevea14050186002425, openalexw14108998, openalexw1624806571"
}

Understanding the origin of volatile element variations in the inner Solar System has long been a goal of cosmochemistry, but many early studies searching for the fingerprint of volatile loss using stable isotope systems failed to find any resolvable variations. An improved method for the chemical purification of Rb for high-precision isotope ratio measurements by multi-collector inductively-coupled-plasma mass-spectrometry. This method has been used to measure the Rb isotopic composition for a suite of planetary materials, including carbonaceous, ordinary, and enstatite chondrites, as well as achondrites (eucrite, angrite), terrestrial igneous rocks (basalt, andesite, granite), and Apollo lunar samples (mare basalts, alkali suite). Volatile depleted bodies (e.g. HED parent body, thermally metamorphosed meteorites) are enriched in the heavy isotope of Rb by up to several per mil compared to chondrites, suggesting volatile loss by evaporation at the surface of planetesimals. In addition, the Moon is isotopically distinct from the Moon in Rb. The variations in Rb isotope compositions in the volatile-poor samples are attributed to volatile loss from planetesimals during accretion. This suggests that either the Rb (and other volatile elements) were lost during or following the giant impact or by evaporation earlier during the accretion history of Theia.

@article{doi101016jepsl201705033,
    author = "Pringle, Emily A. and Moynier, Frédéric",
    title = "Rubidium isotopic composition of the Earth, meteorites, and the Moon: Evidence for the origin of volatile loss during planetary accretion",
    year = "2017",
    journal = "Earth and Planetary Science Letters",
    abstract = "Understanding the origin of volatile element variations in the inner Solar System has long been a goal of cosmochemistry, but many early studies searching for the fingerprint of volatile loss using stable isotope systems failed to find any resolvable variations. An improved method for the chemical purification of Rb for high-precision isotope ratio measurements by multi-collector inductively-coupled-plasma mass-spectrometry. This method has been used to measure the Rb isotopic composition for a suite of planetary materials, including carbonaceous, ordinary, and enstatite chondrites, as well as achondrites (eucrite, angrite), terrestrial igneous rocks (basalt, andesite, granite), and Apollo lunar samples (mare basalts, alkali suite). Volatile depleted bodies (e.g. HED parent body, thermally metamorphosed meteorites) are enriched in the heavy isotope of Rb by up to several per mil compared to chondrites, suggesting volatile loss by evaporation at the surface of planetesimals. In addition, the Moon is isotopically distinct from the Moon in Rb. The variations in Rb isotope compositions in the volatile-poor samples are attributed to volatile loss from planetesimals during accretion. This suggests that either the Rb (and other volatile elements) were lost during or following the giant impact or by evaporation earlier during the accretion history of Theia.",
    url = "https://doi.org/10.1016/j.epsl.2017.05.033",
    doi = "10.1016/j.epsl.2017.05.033",
    openalex = "W2626144397",
    references = "doi101038ncomms8617"
}

g of water averaged over the globe. Formation and migration of water toward cold traps may thus be a continuous process on the Moon and other airless bodies.

@article{doi101126sciadv1701471,
    author = "Li, Shuai and Milliken, R. E.",
    title = "Water on the surface of the Moon as seen by the Moon Mineralogy Mapper: Distribution, abundance, and origins",
    year = "2017",
    journal = "Science Advances",
    abstract = "g of water averaged over the globe. Formation and migration of water toward cold traps may thus be a continuous process on the Moon and other airless bodies.",
    url = "https://doi.org/10.1126/sciadv.1701471",
    doi = "10.1126/sciadv.1701471",
    openalex = "W2754667650",
    references = "doi1010079781461263333, doi101016001910358490054x, doi101016jepsl201410053, doi101017cbo9780511524998, doi101029jb084ib10p05659, doi101029jb086ib04p03039, doi101029jz066i009p03033, doi101038nature07047, doi101126science1178658, doi101126science1179788, doi101126science1235142, doi101126science28153821496"
}

Abstract The giant impact hypothesis remains the leading theory for lunar origin. However, current models struggle to explain the Moon's composition and isotopic similarity with Earth. Here we present a new lunar origin model. High‐energy, high‐angular‐momentum giant impacts can create a post‐impact structure that exceeds the corotation limit, which defines the hottest thermal state and angular momentum possible for a corotating body. In a typical super‐corotation‐limit body, traditional definitions of mantle, atmosphere, and disk are not appropriate, and the body forms a new type of planetary structure, named a synestia. Using simulations of cooling synestias combined with dynamic, thermodynamic, and geochemical calculations, we show that satellite formation from a synestia can produce the main features of our Moon. We find that cooling drives mixing of the structure, and condensation generates moonlets that orbit within the synestia, surrounded by tens of bars of bulk silicate Earth vapor. The moonlets and growing moon are heated by the vapor until the first major element (Si) begins to vaporize and buffer the temperature. Moonlets equilibrate with bulk silicate Earth vapor at the temperature of silicate vaporization and the pressure of the structure, establishing the lunar isotopic composition and pattern of moderately volatile elements. Eventually, the cooling synestia recedes within the lunar orbit, terminating the main stage of lunar accretion. Our model shifts the paradigm for lunar origin from specifying a certain impact scenario to achieving a Moon‐forming synestia. Giant impacts that produce potential Moon‐forming synestias were common at the end of terrestrial planet formation.

@article{doi1010022017je005333,
    author = "Lock, Simon J. and Stewart, Sarah T. and Petaev, M. I. and Leinhardt, Z. M. and Mace, Mia and Jacobsen, S. B. and Ćuk, Matija",
    title = "The Origin of the Moon Within a Terrestrial Synestia",
    year = "2018",
    journal = "Journal of Geophysical Research Planets",
    abstract = "Abstract The giant impact hypothesis remains the leading theory for lunar origin. However, current models struggle to explain the Moon's composition and isotopic similarity with Earth. Here we present a new lunar origin model. High‐energy, high‐angular‐momentum giant impacts can create a post‐impact structure that exceeds the corotation limit, which defines the hottest thermal state and angular momentum possible for a corotating body. In a typical super‐corotation‐limit body, traditional definitions of mantle, atmosphere, and disk are not appropriate, and the body forms a new type of planetary structure, named a synestia. Using simulations of cooling synestias combined with dynamic, thermodynamic, and geochemical calculations, we show that satellite formation from a synestia can produce the main features of our Moon. We find that cooling drives mixing of the structure, and condensation generates moonlets that orbit within the synestia, surrounded by tens of bars of bulk silicate Earth vapor. The moonlets and growing moon are heated by the vapor until the first major element (Si) begins to vaporize and buffer the temperature. Moonlets equilibrate with bulk silicate Earth vapor at the temperature of silicate vaporization and the pressure of the structure, establishing the lunar isotopic composition and pattern of moderately volatile elements. Eventually, the cooling synestia recedes within the lunar orbit, terminating the main stage of lunar accretion. Our model shifts the paradigm for lunar origin from specifying a certain impact scenario to achieving a Moon‐forming synestia. Giant impacts that produce potential Moon‐forming synestias were common at the end of terrestrial planet formation.",
    url = "https://doi.org/10.1002/2017je005333",
    doi = "10.1002/2017je005333",
    openalex = "W2787972555",
    references = "doi1010079781461261674, doi1010079783642303043, doi1010160009254194001404, doi101016b9780080959757002011, doi101016jepsl201410053, doi10103835089010, doi101038nature10201, doi101086158356, doi101086375492, doi101126science1231530, openalexw1612422762"
}

Abstract The Moon is the only planetary body other than the Earth for which samples have been collected in situ by humans and robotic missions and returned to Earth. Scientific investigations of the first lunar samples returned by the Apollo 11 astronauts 50 years ago transformed the way we think most planetary bodies form and evolve. Identification of anorthositic clasts in Apollo 11 samples led to the formulation of the magma ocean concept, and by extension the idea that the Moon experienced large-scale melting and differentiation. This concept of magma oceans would soon be applied to other terrestrial planets and large asteroidal bodies. Dating of basaltic fragments returned from the Moon also showed that a relatively small planetary body could sustain volcanic activity for more than a billion years after its formation. Finally, studies of the lunar regolith showed that in addition to containing a treasure trove of the Moon’s history, it also provided us with a rich archive of the past 4.5 billion years of evolution of the inner Solar System. Further investigations of samples returned from the Moon over the past five decades led to many additional discoveries, but also raised new and fundamental questions that are difficult to address with currently available samples, such as those related to the age of the Moon, duration of lunar volcanism, the lunar paleomagnetic field and its intensity, and the record on the Moon of the bombardment history during the first billion years of evolution of the Solar System. In this contribution, we review the information we currently have on some of the key science questions related to the Moon and discuss how future sample-return missions could help address important knowledge gaps.

@article{doi101007s112140190622x,
    author = "Tartèse, Romain and Anand, M. and Gattacceca, J. and Joy, K. H. and Mortimer, James and Pernet‐Fisher, J. F. and Russell, S. S. and Snape, J. F. and Weiss, B. P.",
    title = "Constraining the Evolutionary History of the Moon and the Inner Solar System: A Case for New Returned Lunar Samples",
    year = "2019",
    journal = "Space Science Reviews",
    abstract = "Abstract The Moon is the only planetary body other than the Earth for which samples have been collected in situ by humans and robotic missions and returned to Earth. Scientific investigations of the first lunar samples returned by the Apollo 11 astronauts 50 years ago transformed the way we think most planetary bodies form and evolve. Identification of anorthositic clasts in Apollo 11 samples led to the formulation of the magma ocean concept, and by extension the idea that the Moon experienced large-scale melting and differentiation. This concept of magma oceans would soon be applied to other terrestrial planets and large asteroidal bodies. Dating of basaltic fragments returned from the Moon also showed that a relatively small planetary body could sustain volcanic activity for more than a billion years after its formation. Finally, studies of the lunar regolith showed that in addition to containing a treasure trove of the Moon’s history, it also provided us with a rich archive of the past 4.5 billion years of evolution of the inner Solar System. Further investigations of samples returned from the Moon over the past five decades led to many additional discoveries, but also raised new and fundamental questions that are difficult to address with currently available samples, such as those related to the age of the Moon, duration of lunar volcanism, the lunar paleomagnetic field and its intensity, and the record on the Moon of the bombardment history during the first billion years of evolution of the Solar System. In this contribution, we review the information we currently have on some of the key science questions related to the Moon and discuss how future sample-return missions could help address important knowledge gaps.",
    url = "https://doi.org/10.1007/s11214-019-0622-x",
    doi = "10.1007/s11214-019-0622-x",
    openalex = "W2990538259",
    references = "doi101016jgca201805006, doi101098rsta20130315"
}

@article{doi101016jepsl2019115771,
    author = "McCubbin, F. M. and Barnes, Jessica",
    title = "Origin and abundances of H2O in the terrestrial planets, Moon, and asteroids",
    year = "2019",
    journal = "Earth and Planetary Science Letters",
    url = "https://doi.org/10.1016/j.epsl.2019.115771",
    doi = "10.1016/j.epsl.2019.115771",
    openalex = "W2971642919",
    references = "doi1010022017je005333, doi1010160012821x96001549, doi101016jepsl201110040, doi10103835089010, doi101038nature10201, doi101086375492, doi101086426895, doi10108800670049208220, doi101093petrology322365, doi101098rsta20150390, doi101111maps12430, doi101111maps12639, doi101111maps12647, doi105860choice264478, openalexw1589757706"
}

Abstract The crystallization of the lunar magma ocean (LMO) determines the initial structure of the solid Moon. Near the end of the LMO crystallization, ilmenite‐bearing cumulates (IBC) form beneath the plagioclase crust. Being denser than the underlying mantle, IBC are prone to overturn, a hypothesis that explains several aspects of the Moon's evolution. Yet the formation of stagnant lid due to the temperature dependence of viscosity can easily prevent IBC from sinking. To infer the rheological conditions allowing IBC to sink, we calculated the LMO crystallization sequence and performed high‐resolution numerical simulations of the overturn dynamics. We assumed a diffusion creep rheology and tested the effects of reference viscosity, activation energy, and compositional viscosity contrast between IBC and mantle. The overturn strongly depends on reference viscosity and activation energy and is facilitated by a low IBC viscosity. For a reference viscosity of 10 21 Pa s, characteristic of a dry rheology, IBC overturn cannot take place. For a reference viscosity of 10 20 Pa s, the overturn is possible if the activation energy is a factor of 2–3 lower than the values typically assumed for dry olivine. These low activation energies suggest a role for dislocation creep. For lower‐reference viscosities associated with the presence of water or trapped melt, more than 95% IBC can sink regardless of the activation energy. Scaling laws for Rayleigh‐Taylor instability confirmed these results but also showed the need of numerical simulations to accurately quantify the overturn dynamics. Whenever IBC sink, the overturn occurs via small‐scale diapirs.

@article{doi1010292018je005739,
    author = "Yu, Shuoran and Tosi, Nicola and Schwinger, Sabrina and Maurice, Maxime and Breuer, D. and Xiao, Long",
    title = "Overturn of Ilmenite‐Bearing Cumulates in a Rheologically Weak Lunar Mantle",
    year = "2019",
    journal = "Journal of Geophysical Research Planets",
    abstract = "Abstract The crystallization of the lunar magma ocean (LMO) determines the initial structure of the solid Moon. Near the end of the LMO crystallization, ilmenite‐bearing cumulates (IBC) form beneath the plagioclase crust. Being denser than the underlying mantle, IBC are prone to overturn, a hypothesis that explains several aspects of the Moon's evolution. Yet the formation of stagnant lid due to the temperature dependence of viscosity can easily prevent IBC from sinking. To infer the rheological conditions allowing IBC to sink, we calculated the LMO crystallization sequence and performed high‐resolution numerical simulations of the overturn dynamics. We assumed a diffusion creep rheology and tested the effects of reference viscosity, activation energy, and compositional viscosity contrast between IBC and mantle. The overturn strongly depends on reference viscosity and activation energy and is facilitated by a low IBC viscosity. For a reference viscosity of 10 21 Pa s, characteristic of a dry rheology, IBC overturn cannot take place. For a reference viscosity of 10 20 Pa s, the overturn is possible if the activation energy is a factor of 2–3 lower than the values typically assumed for dry olivine. These low activation energies suggest a role for dislocation creep. For lower‐reference viscosities associated with the presence of water or trapped melt, more than 95\% IBC can sink regardless of the activation energy. Scaling laws for Rayleigh‐Taylor instability confirmed these results but also showed the need of numerical simulations to accurately quantify the overturn dynamics. Whenever IBC sink, the overturn occurs via small‐scale diapirs.",
    url = "https://doi.org/10.1029/2018je005739",
    doi = "10.1029/2018je005739",
    openalex = "W2911479165",
    references = "doi101016jgca201805006"
}

The lunar surface is ancient and well-preserved, recording Solar System history and planetary evolution processes. Ancient basin-scale impacts excavated lunar mantle rocks, which are expected to remain present on the surface. Sampling these rocks would provide insight into fundamental planetary processes, including differentiation and magmatic evolution. There is contention among lunar scientists as to what lithologies make up the upper lunar mantle, and where they may have been exposed on the surface. We review dynamical models of lunar differentiation in the context of recent experiments and spacecraft data, assessing candidate lithologies, their distribution, and implications for lunar evolution.

@article{doi101038s41467021246263,
    author = "Moriarty, D. P. and Dygert, Nick and Valencia, Sarah and Watkins, Ryan and Petro, N. E.",
    title = "The search for lunar mantle rocks exposed on the surface of the Moon",
    year = "2021",
    journal = "Nature Communications",
    abstract = "The lunar surface is ancient and well-preserved, recording Solar System history and planetary evolution processes. Ancient basin-scale impacts excavated lunar mantle rocks, which are expected to remain present on the surface. Sampling these rocks would provide insight into fundamental planetary processes, including differentiation and magmatic evolution. There is contention among lunar scientists as to what lithologies make up the upper lunar mantle, and where they may have been exposed on the surface. We review dynamical models of lunar differentiation in the context of recent experiments and spacecraft data, assessing candidate lithologies, their distribution, and implications for lunar evolution.",
    url = "https://doi.org/10.1038/s41467-021-24626-3",
    doi = "10.1038/s41467-021-24626-3",
    openalex = "W3189059404",
    references = "doi101016jgca201805006"
}

Lunar soil is a fine mixture of local rocks and exotic components. The bulk-rock chemical composition of the newly returned Chang’E-5 (CE-5) lunar soil was studied to understand its chemical homogeneity, exotic additions, and origin of landing site basalts. Concentrations of 48 major and trace elements, including many low-concentration volatile and siderophile elements, of two batches of the scooped CE-5 soil samples were simultaneously obtained by inductively coupled plasma mass spectrometry (ICP-MS) with minimal sample consumption. Their major and trace elemental compositions (except for Ni) are uniform at milligram levels (2–4 mg), matching measured compositions of basaltic glasses and estimates based on mineral modal abundances of basaltic fragments. This result indicates that the exotic highland and KREEP (K, rare earth elements, and P-rich) materials are very low (<5%) and the bulk chemical composition (except for Ni) of the CE-5 soil can be used to represent the underlying mare basalt. The elevated Ni concentrations reflect the addition of about 1 wt% meteoritic materials, which would not influence the other bulk composition except for some highly siderophile trace elements such as Ir. The CE-5 soil, which is overall the same as the underlying basalt in composition, displays low Mg# (34), high FeO (22.7 wt%), intermediate TiO2 (5.12 wt%), and high Th (5.14 µg/g) concentrations. The composition is distinct from basalts and soils returned by the Apollo and Luna missions, however, the depletion of volatile or siderophile elements such as K, Rb, Mo, and W in their mantle sources is comparable. The incompatible lithophile trace element concentrations (e.g., Ba, Rb, Th, U, Nb, Ta, Zr, Hf, and REE) of the CE-5 basalts are moderately high and their pattern mimics high-K KREEP. The pattern of these trace elements with K, Th, U, Nb, and Ta anomalies of the CE-5 basalts cannot be explained by the partial melting and crystallization of olivine, pyroxene, and plagioclase. Thus, the mantle source of the CE-5 landing site mare basalt could have contained KREEP components, likely as trapped interstitial melts. To reconcile these observations with the initial unradiogenic Sr and radiogenic Nd isotopic compositions of the CE-5 basalts, clinopyroxene characterized by low Rb/Sr and high Sm/Nd ratios could be one of the main minerals in the KREEP-bearing mantle source. Consequently, we propose that the CE-5 landing site mare basalts very likely originated from partial melting of a shallow and clinopyroxene-rich (relative to olivine and orthopyroxene) upper mantle cumulate with a small fraction (about 1–1.5 %) of KREEP-like materials.

@article{doi101016jgca202206037,
    author = "Zong, Keqing and Wang, Zaicong and Li, Jiawei and He, Qi and Li, Yiheng and Becker, Harry and Zhang, Wen and Hu, Zhaochu and He, Tao and Cao, Kenan and She, Zhenbing and Wu, Xiang and Xiao, Long and Liu, Yongsheng",
    title = "Bulk compositions of the Chang’E-5 lunar soil: Insights into chemical homogeneity, exotic addition, and origin of landing site basalts",
    year = "2022",
    journal = "Geochimica et Cosmochimica Acta",
    abstract = "Lunar soil is a fine mixture of local rocks and exotic components. The bulk-rock chemical composition of the newly returned Chang’E-5 (CE-5) lunar soil was studied to understand its chemical homogeneity, exotic additions, and origin of landing site basalts. Concentrations of 48 major and trace elements, including many low-concentration volatile and siderophile elements, of two batches of the scooped CE-5 soil samples were simultaneously obtained by inductively coupled plasma mass spectrometry (ICP-MS) with minimal sample consumption. Their major and trace elemental compositions (except for Ni) are uniform at milligram levels (2–4 mg), matching measured compositions of basaltic glasses and estimates based on mineral modal abundances of basaltic fragments. This result indicates that the exotic highland and KREEP (K, rare earth elements, and P-rich) materials are very low (<5\%) and the bulk chemical composition (except for Ni) of the CE-5 soil can be used to represent the underlying mare basalt. The elevated Ni concentrations reflect the addition of about 1 wt\% meteoritic materials, which would not influence the other bulk composition except for some highly siderophile trace elements such as Ir. The CE-5 soil, which is overall the same as the underlying basalt in composition, displays low Mg\# (34), high FeO (22.7 wt\%), intermediate TiO2 (5.12 wt\%), and high Th (5.14 µg/g) concentrations. The composition is distinct from basalts and soils returned by the Apollo and Luna missions, however, the depletion of volatile or siderophile elements such as K, Rb, Mo, and W in their mantle sources is comparable. The incompatible lithophile trace element concentrations (e.g., Ba, Rb, Th, U, Nb, Ta, Zr, Hf, and REE) of the CE-5 basalts are moderately high and their pattern mimics high-K KREEP. The pattern of these trace elements with K, Th, U, Nb, and Ta anomalies of the CE-5 basalts cannot be explained by the partial melting and crystallization of olivine, pyroxene, and plagioclase. Thus, the mantle source of the CE-5 landing site mare basalt could have contained KREEP components, likely as trapped interstitial melts. To reconcile these observations with the initial unradiogenic Sr and radiogenic Nd isotopic compositions of the CE-5 basalts, clinopyroxene characterized by low Rb/Sr and high Sm/Nd ratios could be one of the main minerals in the KREEP-bearing mantle source. Consequently, we propose that the CE-5 landing site mare basalts very likely originated from partial melting of a shallow and clinopyroxene-rich (relative to olivine and orthopyroxene) upper mantle cumulate with a small fraction (about 1–1.5 \%) of KREEP-like materials.",
    url = "https://doi.org/10.1016/j.gca.2022.06.037",
    doi = "10.1016/j.gca.2022.06.037",
    openalex = "W4283761785",
    references = "doi101038s41586021041079"
}

@article{doi101038s41550022017633,
    author = "Li, Chen and Guo, Zhuang and Li, Yang and Tai, Kairui and Wei, Kuixian and Li, Xiongyao and Liu, Jianzhong and Ma, Wenhui",
    title = "Impact-driven disproportionation origin of nanophase iron particles in Chang’e-5 lunar soil sample",
    year = "2022",
    journal = "Nature Astronomy",
    url = "https://doi.org/10.1038/s41550-022-01763-3",
    doi = "10.1038/s41550-022-01763-3",
    openalex = "W4294051841",
    references = "doi101038s41586021041079"
}

Abstract To address questions about the multiple lunar nearside–farside dichotomies and to provide new insights into both the early impact history of the Solar System and the geological evolution of the Moon, the Chang’e-6 (CE-6) landing zone has been selected to lie within the lunar farside South Pole–Aitken (SPA) basin in the southern part of the Apollo basin (150–158° W, 41–45° S), a site that provides access to a diversity of SPA material. Here, we describe the geomorphology, geology and chronology of three candidate sampling sites within this zone that are likely to ensure safe landing and sampling. The geological characteristics indicate that CE-6 is expected to collect lunar farside SPA ejecta fragments, possible mantle material and young (roughly 2.40 Gyr-year-old) and/or old (roughly 3.43 Gyr-year-old) basaltic material, all of which will provide important guidance for future in situ farside sample collection and deepen our understanding of the evolution of the Moon.

@article{doi101038s41550023020381,
    author = "Zeng, Xingguo and Liu, Dawei and Chen, Yuan and Zhou, Qin and Ren, Xin and Zhang, Zhoubin and Yan, Wei and Chen, Wangli and Wang, Q. and Deng, Xiangjin and Hu, Hao and Liu, Jianjun and Zuo, Wei and Head, J. W. and Li, Chunlai",
    title = "Landing site of the Chang’e-6 lunar farside sample return mission from the Apollo basin",
    year = "2023",
    journal = "Nature Astronomy",
    abstract = "Abstract To address questions about the multiple lunar nearside–farside dichotomies and to provide new insights into both the early impact history of the Solar System and the geological evolution of the Moon, the Chang’e-6 (CE-6) landing zone has been selected to lie within the lunar farside South Pole–Aitken (SPA) basin in the southern part of the Apollo basin (150–158° W, 41–45° S), a site that provides access to a diversity of SPA material. Here, we describe the geomorphology, geology and chronology of three candidate sampling sites within this zone that are likely to ensure safe landing and sampling. The geological characteristics indicate that CE-6 is expected to collect lunar farside SPA ejecta fragments, possible mantle material and young (roughly 2.40 Gyr-year-old) and/or old (roughly 3.43 Gyr-year-old) basaltic material, all of which will provide important guidance for future in situ farside sample collection and deepen our understanding of the evolution of the Moon.",
    url = "https://doi.org/10.1038/s41550-023-02038-1",
    doi = "10.1038/s41550-023-02038-1",
    openalex = "W4385429888",
    references = "doi101016jicarus201512039, doi101016jicarus201605031"
}

Lunar exploration is deemed crucial for uncovering the origins of the Earth-Moon system and is the first step for advancing humanity's exploration of deep space. Over the past decade, the Chinese Lunar Exploration Program (CLEP), also known as the Chang'e (CE) Project, has achieved remarkable milestones. It has successfully developed and demonstrated the engineering capability required to reach and return from the lunar surface. Notably, the CE Project has made historic firsts with the landing and on-site exploration of the far side of the Moon, along with the collection of the youngest volcanic samples from the Procellarum KREEP Terrane. These achievements have significantly enhanced our understanding of lunar evolution. Building on this success, China has proposed an ambitious crewed lunar exploration strategy, aiming to return to the Moon for scientific exploration and utilization. This plan encompasses two primary phases: the first crewed lunar landing and exploration, followed by a thousand-kilometer scale scientific expedition to construct a geological cross-section across the lunar surface. Recognizing the limitations of current lunar exploration efforts and China's engineering and technical capabilities, this paper explores the benefits of crewed lunar exploration while leveraging synergies with robotic exploration. The study refines fundamental lunar scientific questions that could lead to significant breakthroughs, considering the respective engineering and technological requirements. This research lays a crucial foundation for defining the objectives of future lunar exploration, emphasizing the importance of crewed missions and offering insights into potential advancements in lunar science.

@article{doi101016jscib202404051,
    author = "Lin, Yangting and Yang, Wei and Zhang, Hui and Hui, Hejiu and Hu, Sen and Xiao, Long and Liu, Jianzhong and Xiao, Zhiyong and Yue, Zongyu and Zhang, Jinhai and Liu, Yang and Yang, Jing and Lin, Honglei and Zhang, Aicheng and Guo, Dijun and Gou, Sheng and Xu, Lin and He, Yuyang and Zhang, Xianguo and Qin, Liping and Ling, Zongcheng and Li, Xiongyao and Du, Aimin and He, Huaiyu and Zhang, Peng and Cao, Jinbin and Li, Xianhua",
    title = "Return to the Moon: New perspectives on lunar exploration.",
    year = "2024",
    journal = "Science bulletin",
    abstract = "Lunar exploration is deemed crucial for uncovering the origins of the Earth-Moon system and is the first step for advancing humanity's exploration of deep space. Over the past decade, the Chinese Lunar Exploration Program (CLEP), also known as the Chang'e (CE) Project, has achieved remarkable milestones. It has successfully developed and demonstrated the engineering capability required to reach and return from the lunar surface. Notably, the CE Project has made historic firsts with the landing and on-site exploration of the far side of the Moon, along with the collection of the youngest volcanic samples from the Procellarum KREEP Terrane. These achievements have significantly enhanced our understanding of lunar evolution. Building on this success, China has proposed an ambitious crewed lunar exploration strategy, aiming to return to the Moon for scientific exploration and utilization. This plan encompasses two primary phases: the first crewed lunar landing and exploration, followed by a thousand-kilometer scale scientific expedition to construct a geological cross-section across the lunar surface. Recognizing the limitations of current lunar exploration efforts and China's engineering and technical capabilities, this paper explores the benefits of crewed lunar exploration while leveraging synergies with robotic exploration. The study refines fundamental lunar scientific questions that could lead to significant breakthroughs, considering the respective engineering and technological requirements. This research lays a crucial foundation for defining the objectives of future lunar exploration, emphasizing the importance of crewed missions and offering insights into potential advancements in lunar science.",
    url = "https://pubmed.ncbi.nlm.nih.gov/38777682/",
    doi = "10.1016/j.scib.2024.04.051",
    openalex = "W4396217224",
    pmid = "38777682",
    references = "doi101007s1121401096342, doi101016016093279290014g, doi1010291999je001103, doi10103835089010, doi101038nature03676, doi101038nature07047, doi101038news0603135, doi101126science1225542, doi101126science1226073, doi101126science1231530"
}

The lunar mantle is important for unraveling the Moon's formation and early differentiation processes. Here, we identify primitive lunar olivines in soils returned by the Chang'e-6 mission. These olivines have oxygen isotopic compositions plotting along the terrestrial fractionation line, and are characterized by high forsterite contents up to 95.6, and a broad range of nickel abundances from zero to 682 ppm. While the low-nickel (zero to 251 ppm), forsteritic olivines align with a Mg-suite origin, the most primitive, high-nickel olivines (337 to 682 ppm) have a different origin. They could be either the first olivine crystallized from the Lunar Magma Ocean (LMO) with an Earth-like initial composition, or crystallized from a hitherto unrecognized ultra-magnesian lava produced by extensive melting of the early LMO cumulate. The exposure of these mantle olivines was facilitated by their entrainment in ascending high-Mg lavas and conveyed to the surface at the South Pole-Aitken Basin.

@article{doi101038s41467025588204,
    author = "Sheng, Si-Zhang and Wang, Shui-Jiong and Li, Qiu-Li and Wu, Shitou and Wang, Hao and Hua, Jun-Xiang and Chen, Zhenyu and Hao, Jin-Hua and Zhang, Bo and He, Yongsheng and Zhu, Jian-Ming",
    title = "Lunar primitive mantle olivine returned by Chang'e-6.",
    year = "2025",
    journal = "Nature communications",
    abstract = "The lunar mantle is important for unraveling the Moon's formation and early differentiation processes. Here, we identify primitive lunar olivines in soils returned by the Chang'e-6 mission. These olivines have oxygen isotopic compositions plotting along the terrestrial fractionation line, and are characterized by high forsterite contents up to 95.6, and a broad range of nickel abundances from zero to 682 ppm. While the low-nickel (zero to 251 ppm), forsteritic olivines align with a Mg-suite origin, the most primitive, high-nickel olivines (337 to 682 ppm) have a different origin. They could be either the first olivine crystallized from the Lunar Magma Ocean (LMO) with an Earth-like initial composition, or crystallized from a hitherto unrecognized ultra-magnesian lava produced by extensive melting of the early LMO cumulate. The exposure of these mantle olivines was facilitated by their entrainment in ascending high-Mg lavas and conveyed to the surface at the South Pole-Aitken Basin.",
    url = "https://pmc.ncbi.nlm.nih.gov/articles/PMC12019214/",
    doi = "10.1038/s41467-025-58820-4",
    openalex = "W4409704909",
    pmcid = "PMC12019214",
    pmid = "40268907",
    references = "doi101016001670379290172f, doi101016jepsl201102004, doi1010292004gc000816, doi1010292005gc001060, doi1010292011gc003516, doi101093petrology243256, doi101093petrologyegr080, doi101111j15251314201000923x, doi101126science1231530, doi102138rmg2006603"
}