Pristine lunar glasses: Criteria, data, and implications
TL;DR: The examination of glasses from all of the Apollo landing sites has led to the identification of 25 groups of pristine glass as mentioned in this paper and the nickel found in these glasses is shown to be indigenous, not meteoritic contamination, and to be correlated with Mg.
Abstract: The examination of glasses from all of the Apollo landing sites has led to the identification of 25 groups of pristine glass. The nickel found in these glasses is shown to be indigenous, not meteoritic contamination, and to be correlated with Mg. Chemical data indicate that these glasses are more suitable for primary magma than most crystalline mare basalts. In addition, these pristine glasses support the view that assimilative processes involving two cumulative systems in the differentiated mantle operated during mare petrogenesis. Two linear arrays found among the chemistries of the glasses attest to the existence of these interactions. Data suggest that these cumulate components in the mantle continue for 1000 km (laterally) and therefore are likely to be products of a magma ocean that existed early in lunar history.
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TL;DR: The results indicate that, contrary to prevailing ideas, the bulk Moon might not be entirely depleted in highly volatile elements, including water, and the presence of water must be considered in models constraining the Moon’s formation and its thermal and chemical evolution.
Abstract: The Moon is generally thought to have formed and evolved through a single or a series of catastrophic heating events, during which most of the highly volatile elements were lost. Hydrogen, being the lightest element, is believed to have been completely lost during this period. Here we make use of considerable advances in secondary ion mass spectrometry to obtain improved limits on the indigenous volatile (CO(2), H(2)O, F, S and Cl) contents of the most primitive basalts in the Moon-the lunar volcanic glasses. Although the pre-eruptive water content of the lunar volcanic glasses cannot be precisely constrained, numerical modelling of diffusive degassing of the very-low-Ti glasses provides a best estimate of 745 p.p.m. water, with a minimum of 260 p.p.m. at the 95 per cent confidence level. Our results indicate that, contrary to prevailing ideas, the bulk Moon might not be entirely depleted in highly volatile elements, including water. Thus, the presence of water must be considered in models constraining the Moon's formation and its thermal and chemical evolution.
516 citations
Institut de Physique du Globe de Paris1, Washington University in St. Louis2, University of Copenhagen3, Cornell University4, Massachusetts Institute of Technology5, California Institute of Technology6, University of Arizona7, University of Notre Dame8, University of New Mexico9, University of Washington10, Science Applications International Corporation11, University of Hawaii12, Johns Hopkins University Applied Physics Laboratory13
TL;DR: The current state of understanding of the lunar interior is the sum of nearly four decades of work and a range of exploration programs spanning that same time period as discussed by the authors, which is the framework that unifies our knowledge of the structure and composition of the Moon.
Abstract: The current state of understanding of the lunar interior is the sum of nearly four decades of work and a range of exploration programs spanning that same time period. Missions of the 1960s including the Rangers, Surveyors, and Lunar Orbiters, as well as Earth-based telescopic studies, laid the groundwork for the Apollo program and provided a basic understanding of the surface, its stratigraphy, and chronology. Through a combination of remote sensing, surface exploration, and sample return, the Apollo missions provided a general picture of the lunar interior and spawned the concept of the lunar magma ocean. In particular, the discovery of anorthite clasts in the returned samples led to the view that a large portion of the Moon was initially molten, and that crystallization of this magma ocean gave rise to mafic cumulates that make up the mantle, and plagioclase flotation cumulates that make up the crust (Smith et al. 1970; Wood et al. 1970). This model is now generally accepted and is the framework that unifies our knowledge of the structure and composition of the Moon. The intention of this chapter is to review the major advances that have been made over the past decade regarding the constitution of the Moon’s interior. Much of this new knowledge is a direct result of data acquired from the successful Clementine and Lunar Prospector missions, as well as the analysis of new lunar meteorites. As will be seen, results from these studies have led to many fundamental amendments to the magma ocean model.
Much of what we know from sample analyses has been previously summarized elsewhere, and only their most important aspects will be discussed in this chapter. The reader is referred to the relevant chapters in the books Basaltic Volcanism on the Terrestrial Planets (Basaltic Volcanism Study Project 1981), The …
499 citations
Cites background from "Pristine lunar glasses: Criteria, d..."
...The sulfur concentrations of crystalline mare basalts range from an average of 400 ppm in some of the Apollo 15 low-Ti basalts to 2600 ppm in the high-Ti basalts from Apollo 17 (Delano 1986b, and references therein)....
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TL;DR: In this paper, a chemical model for simulating the sources of the lunar mare basalts was developed by considering a modified mafic cumulate source formed during the combined equilibrium and fractional crystallization of a lunar magma ocean (LMO).
442 citations
TL;DR: The early views of the Moon manifested in mythology and art throughout the world were primarily tied to lunar and terrestrial cycles and the relationships between the Sun and the Moon as mentioned in this paper, and many of these early views were associated with the violent or catastrophic events in which the Moon was expunged from the Earth.
Abstract: As with all science, our continually developing concepts of lunar evolution are firmly tied to both new types of observations and the integration of these observations to the known pool of data. This process invigorates the intellectual foundation on which old models are tested and new concepts are built. Just as the application of new observational tools to lunar science in 1610 (Galileo’s telescope) and 1840 (photography) yielded breakthroughs concerning the true nature of the lunar surface, the computational and technological advances highlighted by the Apollo and post-Apollo missions and associated scientific investigations provided a new view of the thermal and magmatic evolution of the Moon.
### 1.1. Pre-Apollo view of the thermal and magmatic evolution of the Moon
Many of the early views of the Moon manifested in mythology and art throughout the world were primarily tied to lunar and terrestrial cycles and the relationships between the Sun and the Moon. Prophetically, myths involving the lunar deities Mwuetsi from Zimbabwe and Coyolxauhqui from Mexico told of rather violent or catastrophic events in which the Moon was expunged from the Earth. Numerous ancient scientific observations were made about the nature of the Moon ranging from those uncovered in early Neolithic sites that correctly identified mare Crisium and mare Humorum to the insights made by Greek philosophers such as Anaxagoras (ca. 500-428 B.C.) and Democritus (ca. 460-370 B.C.), who attached terrestrial analogues to its character (stone, mountains).
With the advent of the telescope (1610) and photography (1840) as scientific tools for lunar exploration, semiquantitative data could be collected that would provide an intellectual foundation for scientific interpretation. Initially, modern terrestrial geological analogs were extended to the Moon (lunar highlands, volcanic craters, seas). Combined with the rigors of computational modeling, these observational data were extended to predict the original thermal state of the Moon and its thermal and magmatic history. Its proximity to the Earth …
437 citations
Cites background or methods from "Pristine lunar glasses: Criteria, d..."
...Figure 4.4 indicates that the TWM composition contains too much Al2O3 to produce the depth and composition of the green glass source region, whereas LPUM agrees well for an LMO depth between 500 km and the entire Moon....
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...The simplest are that: a) the primitive isotopic and trace-element patterns identified in the green glasses (e.g., Delano 1986; Neal 2001) are not intrinsic, but result from some sort of hybridization or assimilation; b) the post-LMO deep melting of the Moon envisioned by Kirk and Stevenson (1989)…...
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...Figure 4.4 also shows that the chondritic (C) composition cannot satisfy the Al2O3 requirement of the Moon unless nearly the entire Moon was initially molten and the extraction of Al2O3 was nearly perfect....
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...The FeO contents of the picritic glasses are roughly twice those of primitive oceanfloor basalts (Delano 1986; Hess 1992)....
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...Apart from high Al2O3 and CaO, and the low Mg′ documented in Chapter 3, the ferroan anorthosites are characterized by low incompatible element abundances with the trivalent REE generally less than chondritic....
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TL;DR: A review of recent developments in the geological analysis of lunar mare volcanism can be found in this paper, where the authors show that mare volcanic activity began prior to the end of heavy bombardment (the period of cryptomare formation), in pre-Nectarian times, and continued until the Copernical Period, the total duration approaching 3.5-4 Ga.
398 citations
References
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01 Jan 1970
TL;DR: Apollo 11 lunar anorthosites properties and characteristics, discussing grain size, Na content, color, density, chemical composition and geomorphic effects are discussed in this article, where the authors also discuss the geomorphological effects of the anorthoSites.
Abstract: Apollo 11 lunar anorthosites properties and characteristics, discussing grain size, Na content, color, density, chemical composition and geomorphic effects
443 citations
01 Jan 1974
TL;DR: In this paper, evidence for and implications of homogeneous accretion of the moon are considered, and the composition of the highland crust is calculated based on the Eu anomaly.
Abstract: Evidence for and implications of homogeneous accretion of the moon are considered Interelement ratios are used to calculate the composition of the highland crust The rare-earth data for the highlands show a positive Eu anomaly, allowing the deduction that the interior has a negative anomaly The Cr/Ni ratios in the highlands are considered in regard to the overall lunar abundance of the siderophile elements These abundance data and the constraints from the heat flow measurements are next used to set limits on the bulk composition for the moon The geochemical constraints are integrated with the petrological and geophysical data in an attempt to provide a consistent model for the geochemical evolution of the moon
205 citations
TL;DR: In this paper, the authors examined the Fe and Mg distribution between coexisting olivine and lunar basaltic liquids produced by equilibrium partial melting of natural lunar samples and found that the distribution coefficients of the conventional distribution coefficients are nearly linear functions of inverse temperature, and the exchange coefficient is nearly independent of temperature and composition within a given magma group.
196 citations
TL;DR: In this article, the authors found that the orange glass droplets from Apollo 11 and 17 sites and the green glasses from the Apollo 15 site may have formed in lava fountains of low-viscosity lunar basaltic magmas.
172 citations
TL;DR: Reflectance spectra from several regional pyroclastic deposits are presented in support of the theory that mantling units have a unique spectral signature indicative of the presence of a significant, Fe-bearing volcanic glass component as mentioned in this paper.
159 citations