Formation of Apollo 15 green glass beads

Arndt, James; Engelhardt, Wolf von; Gonzalez-Cabeza, I.; Meier, Benjamin

doi:10.1029/jb089is01p0c225

Cited by 35 publications

(26 citation statements)

References 9 publications

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“…(1) dt D pCp similar to the Apollo 15 green glasses [Arndt et al, 1984], at rates slower than those they would experience under "free-flight" conditions. The retardation in cooling may be due to a hot vapor environment or to the radiation shielding effect in a dense cloud of radiating droplets.…”

Section: D_•_t = 6 E•o (T•_t•)mentioning

confidence: 84%

“…To elucidate the process of formation we have tried to determine the cooling history of the droplets by an investigation of orange and black glass beads in soil 74220 and by cooling and crystallization experiments with a synthetic melt of orange glass composition. This was performed by the same methods as applied in our previous study of Apollo 15 green glasses [Arndt et al, 1984].…”

Section: Introductionmentioning

confidence: 99%

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Formation of Apollo 17 orange and black glass beads

Arndt¹,

Engelhardt²

1987

J. Geophys. Res.

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Size frequency distributions of the cross sections of orange and black glass beads in the 125–250 µm fraction of soil 74220 have been determined. Cross section medians of black vitrophyric and orange glassy beads in the 125–250 µm fraction are 0.16 mm and 0.14 mm, respectively. The vitrophyric beads contain skeletal olivine crystals mantled by ilmenite. Some beads contain fragments and euhedral crystals of endogeneous olivine. “Free‐flight” cooling rates and the critical cooling rate for crystallization have been determined with a synthetic melt of orange glass composition. The critical cooling rate is approximately 100° C/s. The “free‐flight” cooling rate of droplets 0.16 mm in diameter is approximately 1080° C/s. It is inferred that Apollo 17 orange melt droplets were erupted together with a large mass of hot gas and/or formed a dense cloud of heat‐radiating droplets.

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Section: D_•_t = 6 E•o (T•_t•)mentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Formation of Apollo 17 orange and black glass beads

Arndt¹,

Engelhardt²

1987

J. Geophys. Res.

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“…The presence of surface coatings has been widely attributed to their deposition onto bead exteriors during cooling of clouds of volcanic gas that enveloped the glass beads and modified their cooling rates (Arndt et al, 1984;Arndt and Von Engelhardt, 1987). Though we may not necessarily expect that the surface coatings represent directly the precise composition of the volcanic gas itself, it is nevertheless instructive to examine the composition of this surface coating and see what we can infer about the degassing of other volatile elements during eruption.…”

Section: Degassing During Lunar Volcanic Eruptionsmentioning

confidence: 99%

Water in the Moon's interior: Truth and consequences

Hauri

Saal

Rutherford

et al. 2015

Earth and Planetary Science Letters

200

182

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Available online xxxx Editor: M.M. Hirschmann Keywords: Moon water volatiles geochemistry volcanism petrologyGeochemical data for H 2 O 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 H 2 O/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 H 2 O 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. (E.H. Hauri). straint on high-temperature models that seek to explain the formation and evolution of the Moon. With increasing consideration of the orbital dynamics of the Earth-Moon-Sun system, there now exists a very wide parameter space for planetary collision models to explain the origin of the Moon by a giant impact, with the Moon formed from a circum-terrestrial disk of molten debris ejected by the collision. This class of models can explain the Earth-Moon angular momentum and early thermal history of the Moon (Cameron and Benz, 1991;Canup and Asphaug, 2001;Canup, 2012;Cuk and Stewart, 2012). However, all of these models predict wholesale melting and partial vaporization of the silicate material that enters proto-lunar orbit in the vacuum of space, and thus all of these models, as currently formulated, are u...

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“…4A) pyroxenes are common. The variety of crystal shapes are clearly related to cooling rate and degree of undercooling of the melts (e.g., Donaldson et al 1975;Arndt et al 1984;Faure et al 2003) and not surprisingly, point to very fast cooling rate values (in the order of a few K/s or faster). Furthermore, droplets or grains of metal (typically Fe 98 wt%, Ni 2 wt%) and troilite are present in most of the spherules, and are normally less than 30 µm in diameter.…”

Section: Spherulesmentioning

confidence: 99%

Evidence for K‐rich terranes on Vesta from impact spherules

Barrat¹,

Bohn²,

Gillet³

et al. 2009

Meteorit & Planetary Scien

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Abstract-The howardite-eucrite-diogenite (HED) clan is a group of meteorites that probably originate from the asteroid Vesta. Some of them are complex breccias that contain impact glasses whose compositions mirror that of their source regions. Some K-rich impact glasses (up to 2 wt% K 2 O) suggest that in addition to basalts and ultramafic cumulates, K-rich rocks are exposed on Vesta's surface. One K-rich glass (up to 6 wt% K 2 O), with a felsic composition, provides the first evidence of highly differentiated K-rich rocks on a large asteroid. They can be compared to the rare lunar granites and suggest that magmas generated in a large asteroid are more diverse than previously thought.

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Formation of Apollo 15 green glass beads

Cited by 35 publications

References 9 publications

Formation of Apollo 17 orange and black glass beads

Formation of Apollo 17 orange and black glass beads

Water in the Moon's interior: Truth and consequences

Evidence for K‐rich terranes on Vesta from impact spherules

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