Extraterrestrial Mineralogy: Two major igneous events in the evolution of the Moon

1977 ◽  
Vol 286 (1336) ◽  
pp. 439-451 ◽  
Keyword(s):  
Large Scale ◽  
Bulk Composition ◽  
Large Body ◽  
Uranium Content ◽  
The Moon ◽  
Lunar Crust ◽  
Crust And Upper Mantle ◽  
Lunar Basalts ◽  
Initial Melting ◽  
Mare Basalts

An understanding of the origin of the Moon is strongly dependent upon a knowledge of its bulk composition and thermal history. Both aspects require a detailed consideration of the composition and origin of the lunar crust and of the mantle-derived lunar basalts. The evidence for two major igneous events is discussed, the first being a large-scale melting and fractionation into crust and mantle at —4.6 to —4.5 Ga, and the second a partial melting of the uppermost mantle at —3.8 to — 3.2 Ga. The distribution of uranium is used to place constraints on the minimum extent of initial melting and on the depth at which the mare basalts were generated, using recent lunar heatflow data for a bulk-Moon uranium content of 30 parts/10 9 . The model favours melting of at least 90 % by volume, and a concentration of the high U-contents of the crust and upper mantle by formation of a thick lower mantle of mafic adcumulates ‘barren’ in heat-producing elements. The ‘fertile’ mafic orthocumulates from which the mare basalts were generated are restricted by the model to depths of less than 200 km. A downward revision of the bulk U-content of the Moon results in down-scaling of the other refractory lithophile elements by analogy with the solar-nebula condensation models. This means that the bulk Moon is fairly close in composition to that of the Earth’s mantle, including its iron content but excluding the volatile elements which are strongly depleted in the Moon. Low contents of siderophile and chalcophile elements, and high contents of lithophile refractory elements in the lunar basalts are attributable to the large-scale fractionation into a core, mantle and crust. The hypothesis of an origin for the Moon by fission from a proto-Earth is revived. Earth layering by a heterogeneous accretion sequence would account for non-equilibrium between core and mantle (e.g. nickel distribution) and an outer veneer of volatile-rich condensate that would contribute to subsequent generation of a granitic crust. Early collision with a large body may have caused fission and formation of a proto-Moon from the Earth’s iron-poor, proto-mantle, with loss of volatiles. Early melting of most of the proto-Moon led to strong fractionation such that the crust and mantle-derived basalts appear to have more extreme compositions, relative to Earth basalts, than is indicated by the likely bulk composition of the Moon.

Mare basalt petrogenesis and the composition of the lunar interior

1977 ◽  
Vol 285 (1327) ◽  
pp. 577-586 ◽  
Keyword(s):  
Experimental Investigation ◽  
Recent Literature ◽  
Bulk Composition ◽  
The Moon ◽  
Compositional Model ◽  
Earth’S Mantle ◽  
Source Regions ◽  
Lunar Interior ◽  
Wide Range ◽  
Mare Basalts

Mare basalts, which are believed to form by partial melting at considerable depths in the lunar interior, are capable of providing a wealth of information concerning the compositions of their source regions. Conversely, any acceptable estimate of the lunar bulk composition must in principle be able to provide source regions capable of yielding mare basalts. A wide range of lunar bulk compositions has been proposed in the recent literature. These differ principally in the proportions of involatile elements, e.g. Ca, A1, to elements of moderate volatility, e.g. Mg, Si, Fe. A detailed experimental investigation has been made of the capacity of the Taylor—Jakes compositional model (8.2 % A12O3) to provide source regions for mare basalts. It is demonstrated that this composition is much too rich in alumina to be acceptable. Other lunar bulk compositions even richer inA12O3 such as those advocated by Ganapathy & Anders, Wanke and co-workers and Anderson can likewise be rejected. In order to produce mare basalts, particularly the least fractionated varieties represented by some Apollo 12 and 15 basalts, lunar bulk compositions containing only about 4 % of A12O3 appear to be required. This is similar to the alumina content of the Earth’s mantle. The relative abundances of many other involatile elements, e.g. Ga, U, Ti, r.e.e., Zr, Ba, Sr, may likewise be similar in the Moon and in the Earth’s mantle. These relationships point towards a common origin for the Moon and for the Earth’s mantle.

scholarly journals Magnesium stable isotopes support the lunar magma ocean cumulate remelting model for mare basalts

2018 ◽  
Vol 116 (1) ◽  
pp. 73-78 ◽  
Author(s):  
Fatemeh Sedaghatpour ◽  
Stein B. Jacobsen
Keyword(s):  
Isotopic Composition ◽  
Isotopic Fractionation ◽  
The Moon ◽  
Magma Ocean ◽  
Isotopic Analyses ◽  
Lunar Samples ◽  
Lunar Basalts ◽  
Mg Isotopes ◽  
Isotopic Variations ◽  
Mare Basalts

We report high-precision Mg isotopic analyses of different types of lunar samples including two pristine Mg-suite rocks (72415 and 76535), basalts, anorthosites, breccias, mineral separates, and lunar meteorites. The Mg isotopic composition of the dunite 72415 (δ25Mg = −0.140 ± 0.010‰, δ26Mg = −0.291 ± 0.018‰), the most Mg-rich and possibly the oldest lunar sample, may provide the best estimate of the Mg isotopic composition of the bulk silicate Moon (BSM). This δ26Mg value of the Moon is similar to those of the Earth and chondrites and reflects both the relative homogeneity of Mg isotopes in the solar system and the lack of Mg isotope fractionation by the Moon-forming giant impact. In contrast to the behavior of Mg isotopes in terrestrial basalts and mantle rocks, Mg isotopic data on lunar samples show isotopic variations among the basalts and pristine anorthositic rocks reflecting isotopic fractionation during the early lunar magma ocean (LMO) differentiation. Calculated evolutions of δ26Mg values during the LMO differentiation are consistent with the observed δ26Mg variations in lunar samples, implying that Mg isotope variations in lunar basalts are consistent with their origin by remelting of distinct LMO cumulates.

scholarly journals P-bearing olivines of lunar rocks: sources and localization in the lunar crust

2019 ◽  
Vol 64 (8) ◽  
pp. 803-825
Author(s):  
S. I. Demidovaa ◽  
M. O. Anosova ◽  
N. N. Kononkova ◽  
T. Ntaflos ◽  
F. Brandstätter
Keyword(s):  
Late Stage ◽  
The Moon ◽  
Local Distribution ◽  
Lunar Crust ◽  
Lunar Material ◽  
Incompatible Elements ◽  
Lunar Samples ◽  
Lunar Rocks ◽  
Mare Basalts

Fragments of P-bearing olivine have been studied in lunar highland, mare and mingled meteorites and in «Apollo-14», «Luna-16, -20, -24» lunar samples. Olivine contains up to 0.5 wt.% P2O5 and has variable MG# number. It is associated with anorthite, pyroxene and accessory spinel group minerals, Ti and Zr oxides, phosphates, troilite and Fe-Ni metal. Three possible sources of P-bearing olivine were found in lunar material: 1) highland anorthositic-noritic-troctolitic rocks enriched in incompatible elements and thought to be related to high-Mg suite rocks: 2) late-stage products of mare basalts crystallization; 3) unusual olivine-orthopyroxene intergrowths either of meteoritic or lunar origin. Enrichment in incompatible elements may be resulted from both crystallization processes (source 2) and KREEP assimilation (sources 1 and 3). However following metasomatic processes can lead to some addition of phosphorus and other elements. The rarity of P-bearing olivines points either to the low abundance or local distribution of their sources in the lunar crust. Association with mare basalts specifies the highland-mare boundary. The presence of the evolved rocks in the studied breccias suggests possible connection of some sources with recently discovered granitic domes in Procellarum Ocean. That means the P-bearing sources are mainly localized on the visible side of the Moon.

Lithium and halogens in lunar samples

1977 ◽  
Vol 285 (1327) ◽  
pp. 49-54 ◽  
Keyword(s):  
Bulk Composition ◽  
Fluorine Content ◽  
The Other ◽  
The Moon ◽  
Rock Samples ◽  
A Value ◽  
Refractory Elements ◽  
Incompatible Elements ◽  
Lunar Samples ◽  
Mare Basalts

Lithium and the halogen elements F, Cl, Br and I have been measured in soils, breccias and rock samples from all Apollo missions. With the exception of the anorthosites, the fluorine content of the lunar samples is in the same range as for C l chondrites. Contrary to fluorine the other halogen concentrations show large variations. The lowest concentrations are found in the mare basalts of Apollo 15 and 17, the highest in some highland breccias. Lithium correlates well with some of the incompatible elements in both mare basalts and 'KREEP’-containing highland soils and breccias. From the observed ratios it is evident that in the bulk composition of the Moon Li is neither enriched nor depleted; it belongs to the group of non-refractory elements. From the correlation of Li with some refractory elements (Be, La, etc.) a value of 50:50 for the refractory to non-refractory portion of the Moon is inferred without any further assumption, thus confirming previous estimates of Wanke et al. (1974a, 1975)

The early chronology of the Moon: evidence for the early collisional history of the solar system

1977 ◽  
Vol 285 (1327) ◽  
pp. 97-103 ◽  
Keyword(s):  
Early Period ◽  
Gravitational Energy ◽  
Magmatic Activity ◽  
The Moon ◽  
Lunar Crust ◽  
Lunar Science ◽  
History Of ◽  
The One ◽  
Mare Basalts ◽  
Age Determinations

A major aim of lunar science has been to understand the early evolution to the lunar crust in the period prior to the extrusion of the mare basalts. There are two aspects to this early period of evolution about which age determinations provide information. On the one hand is the magmatic activity which led to the chemical differentiation of the outer regions of the Moon, while on the other is the bombardment of the Moon by large objects in the period immediately following its formation. The two aspects are probably not unrelated in that the bombardment may represent the final stages of the accretion of the Moon, and the heat source responsible for the initial differentiation was possibly the gravitational energy released during the major accretion phase. 40Ar-39Ar ages have been largely reset by the final stages of the bombardment and therefore most of the information obtained from argon measurements pertains to the chronology of the bombardment. Information on the magmatic activity is obtained from Rb-Sr, U, Th-Pb and Sm-Nd studies.

scholarly journals The chlorine isotope fingerprint of the lunar magma ocean

2015 ◽  
Vol 1 (8) ◽  
pp. e1500380 ◽  
Author(s):  
Jeremy W. Boyce ◽  
Allan H. Treiman ◽  
Yunbin Guan ◽  
Chi Ma ◽  
John M. Eiler ◽  
...  
Keyword(s):  
Solar System ◽  
Isotope Ratios ◽  
Terrestrial Planets ◽  
The Moon ◽  
Magma Ocean ◽  
Chlorine Isotope ◽  
Important Stage ◽  
Lunar Basalts ◽  
Lunar Mare ◽  
Mare Basalts

The Moon contains chlorine that is isotopically unlike that of any other body yet studied in the Solar System, an observation that has been interpreted to support traditional models of the formation of a nominally hydrogen-free (“dry”) Moon. We have analyzed abundances and isotopic compositions of Cl and H in lunar mare basalts, and find little evidence that anhydrous lava outgassing was important in generating chlorine isotope anomalies, because 37Cl/35Cl ratios are not related to Cl abundance, H abundance, or D/H ratios in a manner consistent with the lava-outgassing hypothesis. Instead, 37Cl/35Cl correlates positively with Cl abundance in apatite, as well as with whole-rock Th abundances and La/Lu ratios, suggesting that the high 37Cl/35Cl in lunar basalts is inherited from urKREEP, the last dregs of the lunar magma ocean. These new data suggest that the high chlorine isotope ratios of lunar basalts result not from the degassing of their lavas but from degassing of the lunar magma ocean early in the Moon’s history. Chlorine isotope variability is therefore an indicator of planetary magma ocean degassing, an important stage in the formation of terrestrial planets.

scholarly journals From “the Moon Is Rounder Abroad” to “Bravo, My Country”: How China Misperceives the World

2021 ◽  
Vol 56 (1) ◽  
pp. 112-130 ◽  
Author(s):  
Haifeng Huang
Keyword(s):  
Large Scale ◽  
Chinese Society ◽  
The Moon ◽  
Foreign Countries ◽  
The Social ◽  
The World ◽  
Long Time ◽  
Global Affairs ◽  
Chinese Public

AbstractFor a long time, since China’s opening to the outside world in the late 1970s, admiration for foreign socioeconomic prosperity and quality of life characterized much of the Chinese society, which contributed to dissatisfaction with the country’s development and government and a large-scale exodus of students and emigrants to foreign countries. More recently, however, overestimating China’s standing and popularity in the world has become a more conspicuous feature of Chinese public opinion and the social backdrop of the country’s overreach in global affairs in the last few years. This essay discusses the effects of these misperceptions about the world, their potential sources, and the outcomes of correcting misperceptions. It concludes that while the world should get China right and not misinterpret China’s intentions and actions, China should also get the world right and have a more balanced understanding of its relationship with the world.

scholarly journals Bayesian constraints on the origin and geology of exo-planetary material using a population of externally polluted white dwarfs

2021 ◽  
Author(s):  
John H D Harrison ◽  
Amy Bonsor ◽  
Mihkel Kama ◽  
Andrew M Buchan ◽  
Simon Blouin ◽  
...  
Keyword(s):  
Solar System ◽  
White Dwarf ◽  
Bayesian Model ◽  
Total Mass ◽  
White Dwarfs ◽  
Bulk Composition ◽  
Planetary Systems ◽  
The Moon ◽  
Planetary Bodies ◽  
Nearby Stars

Abstract White dwarfs that have accreted planetary bodies are a powerful probe of the bulk composition of exoplanetary material. In this paper, we present a Bayesian model to explain the abundances observed in the atmospheres of 202 DZ white dwarfs by considering the heating, geochemical differentiation, and collisional processes experienced by the planetary bodies accreted, as well as gravitational sinking. The majority (>60%) of systems are consistent with the accretion of primitive material. We attribute the small spread in refractory abundances observed to a similar spread in the initial planet-forming material, as seen in the compositions of nearby stars. A range in Na abundances in the pollutant material is attributed to a range in formation temperatures from below 1,000 K to higher than 1,400 K, suggesting that pollutant material arrives in white dwarf atmospheres from a variety of radial locations. We also find that Solar System-like differentiation is common place in exo-planetary systems. Extreme siderophile (Fe, Ni or Cr) abundances in 8 systems require the accretion of a core-rich fragment of a larger differentiated body to at least a 3σ significance, whilst one system shows evidence that it accreted a crust-rich fragment. In systems where the abundances suggest that accretion has finished (13/202), the total mass accreted can be calculated. The 13 systems are estimated to have accreted masses ranging from the mass of the Moon to half that of Vesta. Our analysis suggests that accretion continues for 11Myrs on average.

scholarly journals Large-scale variation in seismic anisotropy in the crust and upper mantle beneath Anatolia, Turkey

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Cédric P. Legendre ◽  
Li Zhao ◽  
Tai-Lin Tseng
Keyword(s):  
Upper Mantle ◽  
Large Scale ◽  
Seismic Anisotropy ◽  
Crust And Upper Mantle ◽  
Wave Splitting ◽  
Mantle Processes ◽  
Open Question ◽  
Subduction System ◽  
Anisotropic Phase ◽  
Regional Tectonics

AbstractThe average anisotropy beneath Anatolia is very strong and is well constrained by shear-wave splitting measurements. However, the vertical layering of anisotropy and the contribution of each layer to the overall pattern is still an open question. Here, we construct anisotropic phase-velocity maps of fundamental-mode Rayleigh waves for the Anatolia region using ambient noise seismology and records from several regional seismic stations. We find that the anisotropy patterns in the crust, lithosphere and asthenosphere beneath Anatolia have limited amplitudes and are generally consistent with regional tectonics and mantle processes dominated by the collision between Eurasia and Arabia and the Aegean/Anatolian subduction system. The anisotropy of these layers in the crust and upper mantle are, however, not consistent with the strong average anisotropy measured in this area. We therefore suggest that the main contribution to overall anisotropy likely originates from a deep and highly anisotropic region round the mantle transition zone.

scholarly journals China's Chang'e-5 Landing Site: An Overview

2021 ◽  
Author(s):  
Yuqi Qian ◽  
Long Xiao ◽  
James Head ◽  
Carolyn van der Bogert ◽  
Harald Hiesinger ◽  
...  
Keyword(s):  
Thermal Evolution ◽  
Source Region ◽  
Landing Site ◽  
Volcanic Complex ◽  
The Moon ◽  
Age Variations ◽  
Specific Source ◽  
Scientific Significance ◽  
Lunar Chronology ◽  
Mare Basalts

<p><strong>Introduction</strong></p><p>The Chang’e-5 (CE-5) mission is China’s first lunar sample return mission. CE-5 landed at Northern Oceanus Procellarum (43.1°N, 51.8°W) on December 1, 2020, collected 1731 g of lunar samples, and returned to the Earth on December 17, 2020. The CE-5 landing site is ~170 km ENE of Mons Rümker [1], characterized by some of the youngest mare basalts (Em4/P58) on the Moon [2,3], which are never sampled by the Apollo or Luna missions [4]. This study describes the geologic background of the CE-5 landing site in order to provide context for the ongoing sample analysis.</p><p><strong>Northern Oceanus Procellarum</strong></p><p>Northern Oceanus Procellarum is in the northwest lunar nearside, and the center of the Procellarum-KREEP-Terrane [5], characterized by elevated heat-producing elements and prolonged volcanism. This region exhibits a huge volcanic complex, i.e., Mons Rümker [1], and two episodes of mare eruptions, i.e., Imbrian-aged low-Ti mare basalts in the west and Eratosthenian-aged high-Ti mare basalts (Em3 and Em4/P58) in the east [2]. The longest sinuous rille on the Moon [6], Rima Sharp, extends across Em4/P58. Both the Imbrian-aged (NW-SE) and Eratosthenian-aged (NE-SW) basalts display wrinkle ridges, indicating underlying structures, with different dominant orientations [2].</p><p><strong>Young Mare Basalts</strong></p><p>The Em4/P58 mare basaltic unit, on which CE-5 landed, is one of the youngest mare basalts on the Moon. Various researchers found different CSFD results; however, all of them point to an Eratosthenian age for Em4/P85 (1.21 Ga [2], 1.33 Ga [7,8], 1.53 Ga [3], 1.91 Ga [9]), and there are minor age variations across Em4/P58 [3]. Em4/P58 mare basalts have high-Ti, relatively high-olivine and high-Th abundances, while clinopyroxene is the most abundant mineral type [2,3]. Em4/P58 mare basalts cover an area of ~37,000 km<sup>2</sup>, with a mean thickness of ~51 m and volume of ~1450-2350 km<sup>3</sup> [3]. No specific source vents were found within the unit, and Rima Sharp is the most likely source region for the Em4/P58 mare basalts [3].</p><p><strong>Scientific Significance of the Returned Samples</strong></p><p>The scientific significance of the young mare basalts is summarized in our previous studies [2,3]. In [3], we first summarized the 27 fundamental questions that may be answered by the returned CE-5 samples, including questions about chronology, petrogenesis, regional setting, geodynamic & thermal evolution, and regolith formation (<strong>Tab. 1</strong> in [3]), especially calibrating the lunar chronology function, constraining the lunar dynamo status, unraveling the deep mantle properties, and assessing the Procellarum-KREEP-Terrain structures.</p><p><strong>References</strong></p><p>[1] Zhao J. et al. (2017) JGR, 122, 1419–1442. [2] Qian Y. et al (2018) JGR, 123, 1407–1430. [3] Qian Y. et al. (2021) EPSL, 555, 116702. [4] Tartèse R. et al. (2019) Space Sci. Rev., 215, 54. [5] Jolliff B. L. et al. (2000) JGR, 105, 4197–4216. [6] Hurwitz D. M. et al. (2013) Planet. Space Sci., 79–80, 1–38. [7] Hiesinger H. et al. (2003) JGR, 108, 1–1 (2003). [8] Hiesinger H. et al. (2011) Geol. Soc. Am., 477, 1–51. [9] Morota T. et al. (2011) EPSL, 302, 255–266.</p>

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