Provenance and Pb isotopic ages of lunar volcanic and impact glasses from the Apollo 17 landing site

Norman, Marc D.; Adena, K J D; Christy, Andrew G.

doi:10.1080/08120099.2011.615471

Cited by 20 publications

(29 citation statements)

References 49 publications

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“…Figure presents the chemical characteristics (i.e., (SiO 2 + FeO + MgO)/(SiO 2 + Al 2 O 3 + CaO) ratio vs. SCFM index) of a wide range of lunar pyroclastic glasses (sampled by Apollo 11, 12, 14, 15, and 17 missions), impact mare glasses, and impact highland glasses from Apollo‐returned samples and the randomly ejected lunar breccia meteorites (e.g., Collareta et al, ; Delano, ; Mercer et al, ; Norman et al, ; Wieczorek et al, ; Wittmann et al, ; Zeigler et al, ). It is clear that the pyroclastic glasses have lower SCFM index and higher (SiO 2 + FeO + MgO)/(SiO 2 + Al 2 O 3 + CaO) ratios, compared with impact‐generated mare and highland glasses (Figure ).…”

Section: Discussionmentioning

confidence: 99%

“…(SiO 2 + FeO + MgO)/(SiO 2 + Al 2 O 3 + CaO) ratio versus the SCFM index SiO 2 /(SiO 2 + CaO + FeO + MgO) for lunar pyroclastic glasses (sampled by Apollo 11, 12, 14, 15, and 17 missions), mare impact glasses, and highland impact glasses. The chemical composition of lunar glasses returned by Apollo missions were taken from a wide range of literatures (Zeigler et al, ; Table A3.12 of Wieczorek et al, ; Korotev et al ; Norman et al, ). Chemical composition of glasses from lunar breccia meteorites were also plotted for comparison (Arai & Warren, ; Collareta et al, ; Day et al, ; Delano, ; Korotev et al, , ; Mercer et al, ; Nagaoka et al, ; Snape et al, ; Wittmann et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…In fact, none of the criteria (including chemical composition and texture) are completely diagnostic when treated individually, but they are useful for distinguishing lunar glasses when a number of criteria are Apollo 11,12,14,15,and 17 missions), mare impact glasses, and highland impact glasses. The chemical composition of lunar glasses returned by Apollo missions were taken from a wide range of literatures ; Table A3.12 of Wieczorek et al, 2006;Korotev et al 2010;Norman et al, 2012). Chemical composition of glasses from lunar breccia meteorites were also plotted for comparison (Arai & Warren, 1999;Collareta et al, 2016;Day et al, 2006;Delano, 1991;Korotev et al, 1996Korotev et al, , 2006Mercer et al, 2013;Nagaoka et al, 2013;Snape et al, 2011;Wittmann et al, 2014).…”

Section: 1029/2019je006237mentioning

confidence: 99%

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Micro‐FTIR Spectroscopy of Lunar Pyroclastic and Impact Glasses as a New Diagnostic Tool to Discern Them

Zeng

Martín

et al. 2019

JGR Planets

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Lunar glasses are characterized by complex origin (i.e., volcanism or impact), compositional diversity (e.g., picritic, basaltic, or feldspathic), and visible/near‐infrared spectra similarity. This makes it is problematic to distinguish different types of lunar glasses in laboratory and remote data. In this study, we present micro‐FTIR (Fourier Transform Infrared) spectroscopy spectra (550–1450 cm–1) of a suite of lunar volcanic origin glasses (i.e., pyroclastic glasses) and impact‐generated glasses (i.e., mare and highland impact glasses), identified in lunar breccia meteorite Northwest Africa 7948. The results show that lunar pyroclastic glasses, mare impact glasses, and highland impact glasses exhibit different FTIR spectral characteristics: (1) the Christiansen Feature positions of pyroclastic glasses are generally at a longer wavelength (i.e., >~8.3 μm equivalent to <~1,205 cm–1) than the spectra of mare and highland impact‐generated glasses (i.e., <~8.3 μm equivalent to >~1,205 cm–1); (2) a relatively strong minor peak was distinctly observed at longer wavelength (~13.5–16.5 μm equivalent to ~600–750 cm–1) for highland impact glasses. Therefore, new supplementary FTIR diagnostic criteria were proposed to discern different types of lunar glasses. Our studies demonstrated that midinfrared spectra could provide an effective tool to non‐destructively and quickly distinguish lunar glasses in laboratory (e.g., for the future Chang'E‐5 returned soils).

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: 1029/2019je006237mentioning

confidence: 99%

See 1 more Smart Citation

Micro‐FTIR Spectroscopy of Lunar Pyroclastic and Impact Glasses as a New Diagnostic Tool to Discern Them

Zeng

Martín

et al. 2019

JGR Planets

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“…Impact glass spherules, a kind of impact melt product, are up to 1-mm diameter in size and produced by hypervelocity impacts (Delano et al, 1982;Melosh & Vickery, 1991;Reid et al, 1977). The ubiquity of spherules and their age distribution suggests that they are produced in relatively small impacts (e.g., Delano, 1991;Horz & Cintala, 1997;Korotev et al, 2010;Norman et al, 2012;Symes et al, 1998;Zeigler et al, 2006) and therefore are potentially a powerful record of the impact history since the end of the basin-forming epoch at 3.9 Ga (e.g., Tera et al, 1974).…”

Section: Introductionmentioning

confidence: 99%

No Change in the Recent Lunar Impact Flux Required Based on Modeling of Impact Glass Spherule Age Distributions

Huang

Minton

Zellner

et al. 2018

Geophysical Research Letters

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The distributions of 40 Ar/ 39 Ar-derived ages of impact glass spherules in lunar regolith samples show an excess at <500 Ma relative to older ages. It has not been well understood whether this excess of young ages reflects an increase in the recent lunar impact flux or is due to a bias in the samples. We developed a model to simulate the production, transport, destruction, and sampling of lunar glass spherules. A modeled bias is seen when either (1) the simulated sampling depth is 10 cm, consistent with the typical depth from which Apollo soil samples were taken, or (2) when glass occurrence in the ejecta is limited to >10 crater radii from the crater, consistent with terrestrial microtektite observations. We suggest that the observed excess of young ages for lunar impact glasses is likely due to limitations of the regolith sampling strategy of the Apollo program, rather than reflecting a change in the lunar impact rate.Plain Language Summary Lunar regolith samples collected by the Apollo astronauts contain impact glass spherules that record the age of formation in the Ar-Ar isotope dating system. There are as many spherules with measured ages within the last 500 million years as there is in the previous 4 billion years of lunar history, and it has remained a mystery as to whether this is because the impact rate was higher in the recent past, or if there was some process that was biasing these samples toward a young age. We have developed a three-dimensional computer model that simulates the production, transport, destruction, and sampling of impact-generated glass spherules on the Moon. Using reasonable assumptions that are backed up from data on Earth craters, we are able to reproduce the observed excess of young spherule ages seen in the Apollo samples assuming that impact rate has not changed over the last three billion years. We find that the young age bias is only seen because the Apollo samples were collected in the upper few centimeters of the lunar surface. Future glasses collected from the upper few meters of the surface should have ages that better reflect the true rate of impacts over time.

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“…In order to distinguish among specific impact events, Hui et al (2010) reported major-and minor-element compositions in addition to the 40 Ar/ 39 Ar ages for the impact glasses. Norman et al (2012) suggested that in excess of 30% of glasses in a sample set could have been formed during the same impact event (i.e., glasses with the same composition and age). Even after accounting for multiple glasses formed in the same event, Hui et al (2010) reported a high proportion of glasses (i.e., 'spherules') with ages <500 Ma, which they interpreted as being due to an increase in the recent impact flux (<500 Ma), though they reported that regolith dynamics or surface collection could also be a possible explanation.…”

Section: Introductionmentioning

confidence: 99%

40 Ar/ 39 Ar ages of lunar impact glasses: Relationships among Ar diffusivity, chemical composition, shape, and size

Zellner

Delano

2015

Geochimica et Cosmochimica Acta

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Lunar impact glasses, which are quenched melts produced during cratering events on the Moon, have the potential to provide not only compositional information about both the local and regional geology of the Moon but also information about the impact flux over time. We present in this paper the results of 73 new 40 Ar/ 39 Ar analyses of well-characterized, inclusion-free lunar impact glasses and demonstrate that size, shape, chemical composition, fraction of radiogenic 40 Ar retained, and cosmic ray exposure (CRE) ages are important for 40 Ar/ 39 Ar investigations of these samples. Specifically, analyses of lunar impact glasses from the Apollo 14, 16, and 17 landing sites indicate that retention of radiogenic 40 Ar is a strong function of post-formation thermal history in the lunar regolith, size, and chemical composition. This is because the Ar diffusion coefficient (at a constant temperature) is estimated to decrease by $3-4 orders of magnitude with an increasing fraction of non-bridging oxygens, X(NBO), over the compositional range of most lunar impact glasses with compositions from feldspathic to basaltic. Based on these relationships, lunar impact glasses with compositions and sizes sufficient to have retained $90% of their radiogenic Ar during 750 Ma of cosmic ray exposure at time-integrated temperatures of up to 290 K have been identified and are likely to have yielded reliable 40 Ar/ 39 Ar ages of formation. Additionally, $50% of the identified impact glass spheres have formation ages of 6500 Ma, while $75% of the identified lunar impact glass shards and spheres have ages of formation 62000 Ma. Higher thermal stresses in lunar impact glasses quenched from hyperliquidus temperatures are considered the likely cause of poor survival of impact glass spheres, as well as the decreasing frequency of lunar impact glasses in general with increasing age. The observed age-frequency distribution of lunar impact glasses may reflect two processes: (i) diminished preservation due to spontaneous shattering with age; and (ii) preservation of a remnant population of impact glasses from the tail end of the terminal lunar bombardment having 40 Ar/ 39 Ar ages up to 3800 Ma. A protocol is described for selecting and analyzing lunar impact glasses.

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Provenance and Pb isotopic ages of lunar volcanic and impact glasses from the Apollo 17 landing site

Cited by 20 publications

References 49 publications

Micro‐FTIR Spectroscopy of Lunar Pyroclastic and Impact Glasses as a New Diagnostic Tool to Discern Them

Micro‐FTIR Spectroscopy of Lunar Pyroclastic and Impact Glasses as a New Diagnostic Tool to Discern Them

No Change in the Recent Lunar Impact Flux Required Based on Modeling of Impact Glass Spherule Age Distributions

40 Ar/ 39 Ar ages of lunar impact glasses: Relationships among Ar diffusivity, chemical composition, shape, and size

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