Investigation of glass particles recovered from Apollo 11 and 12 fines: Implications concerning the composition of the lunar surface (original) (raw)
Related papers
Investigation of glass recovered from Apollo 12 sample 12057
Journal of Geophysical Research, 1971
Glass particles from a 500-mg sample of <(1-m•n fines from lunar soil (sample 12057) have been studied in detail. Glassy particles make up •30% of the sample. Glass' spherules compose ~1% of the sample. Scanning electron microscope studies reveal surface features (metallic beads, 'splash' features, and impact pits) similar to those observed on Apollo 11 glasses. Petrographie studies indieate•the presence of mineral inclusions and Ni-Fe metallic spherules in many of the glass particles. Small (~4-•m diameter) Ni-Fe octahedral crystals were found in two glass particles, and a SiO• glass inclusion (leehatelierite) was found in one glass spherule. One hundred twenty-five glass particles were analyzed by electron microprobe. On the basis of their physical and chemical properties, the glasses from sample 12057 can be divided into at least six groups: (1) normal basaltic glasses (~35% of the analyzed glasses) with compositions similar to the Apollo 12 crystalline rocks, (2) low-alkali basaltic glasses (~20%) that are probably derived from the normal basaltic glasses by vapor fractionation, (3) high-alkali basaltic glasses (~20%), which may represent the so-called 'cryptic' component needed to explain the difference in composition between the crystalline rocks and the fines, (4) anorthositic glasses (~16%) that may be from the highlands, (5) high-Ti glasses (~2%) that are similar in composition to many of the Apollo 11 glasses, and (6) anorthiterich glasses (~2%). All the glasses were probably produced by meteorite impact.
Composition and origin of lithic fragments and glasses in apollo 11 samples
Contributions to Mineralogy and Petrology, 1971
Approximately 100 glasses and 52 lithic fragments from Apollo 11 lunar fines and microbreccias were analyzed with the electron microprobe. Ranges in bulk composition of tithie fragments are considerably outside the precision (< =]= 1%) and accuracy (=]= 2-5%) of the broad electron beam technique. Results of this study may be summarized as follows: i) A large variety of rock types different from the hand specimens (basalt) were found among the lithic fragments, namely anorthosites, troctolitie and noritic anorthosites, troctolites, and norites (different from Apollo 12 norites), if) In analogy to the hand specimens, the basaltic lithie fragments may be subdivided into low-K and high-K groups, both of which extend considerably in composition beyond the hand specimens, iii) Glasses were dividedinto 6 groups: Group 1 are the compositional analogs of the anorthositie-troetotitic lithie fragments and were apparently formed in single-stage impact events directly from parent anorthosites and troctelites, iv) Group 2 glasses are identical in composition to Apollo 12 KREEP glass and noritic lithic fragments, but have no counterparts in our Apollo 11 lithic fragment suite. Occurrence of KREEP in Apollo 11, 12, and 14 samples is indicative of its relatively high abundance and suggests that the lunar crust is less depleted in elements that are comm on in KREEP (e.g. K, rare earths, P) than was originally thought on the basis of Apollo 11 basalt studies, v) Group 3 glasses are the compositional analogs of the basaltic lithic fragments, but low-K and high-K glasses cannot be distinguished because of loss of K (and Na, P) by volatilization in the vitrification process, vi) Group 4 glasses have no compositional analogs among the lithic fragments and were probably derived from as yet unknown Fe-rich, moderately Ti-rich, Mg-poor basalte. vii) Group 5 (low Ti-high Mg peridotite equivalent) and 6 (ilmenite peridotite equivalent) glasses have no counterparts among the Apollo 11 lithic fragments, but rock equivalents to group 5 glasses were found in Apollo 12 samples. Group 6 glasses are abundant, have narrow compositional ranges, and are thought to be the products of impact melting of an as yet unrecognized ultramafic rock type. fix) The great variety of igneous rocks (e.g. anorthosites, troctolites, norites, basalts, peridotites) suggests that large scale melting or partial melting to considerable depth must have occurred on the moon.
Geochimica et Cosmochimica Acta, 1991
Most @asses that occur in lunar highland regolith are quenched droplets of impact melt. The chemical compositions of these glasses are equivalent, in the absence of volatile losses, to the original target materials. The compositional range of impact glasses in a regolith reflects the chemical diversity that existed throughout the region up to the time of system closure (e.g., breccia formation). Since these glasses are a product of widespread and random sampling, both in terms of space and time, they can be used for geochemical exploration of the Moon. The major-element compositions of impact glasses occurring in three samples of lunar feldspathic regolith (ALHAS 1005; MAC88105; Apollo 16 64001) have been determined by electron microprobe. The glass populations among these three unrelated samples are compositionally distinct. While most of the impact glasses within each of these three samples are compositionally similar to the regolith in which they are found, up to 40% of the impact glasses are different. Some of the compositionally exotic glasses were ballistically transported from other areas of the Moon and thereby provide information about the compositional range of regoliths that exist elsewhere. Since the geological setting of the Apollo 16 region is well known compared to the source areas of the lunar meteorites, the Apollo 16 glasses provide a ground truth for interpretations. The thirty-four impact glasses in meteorite ALHA 1005 overlap the compositional range of feldspathic regoliths represented by all of the lunar highland meteorites (i.e., Y8603 1; Y82 192; Y79 1197; MAC88 105; ALHA 1005) and are compositionally distinct from highland regoliths sampled by Apollo 14, Apollo 16, Apollo 17, and Luna 20. A small proportion of ALHA 1005 glasses contain a mare component. No KREEP glasses were observed. Due to their scarcity, only ten impact glasses in lunar meteorite MAC88 105 were analyzed. The spherules occur in two, broadly defined, compositional groups. One group of glasses is similar to the bulk composition of MAC88105, whereas the other group is more mafic. All of these glasses are distinct from highland regoliths sampled by Apollo 14, Apollo 16, and Apollo 17, and Luna 20. A low-Ti mare glass was also analyzed in MAC88105. No KREEP glasses were observed. The two hundred and fifty-three aluminous impact glasses analyzed in Apollo 16 regolith 6400 1 display a prominent grouping of compositions equivalent to the local regolith. In addition, about 10% of the glasses in 64001 are distinct from the local regolith and chemically resemble the lunar highland meteorites (ALHA 1005; MAC88 105). These glasses may record the chemical composition of an ancient regolith that occurred in the Apollo 16 region prior to the arrival of KREEP and mare components, Twentythree percent of the glasses in 64001 have high-Ti mare affinities. These mare glasses are clearly exotic to the Apollo 16 site and have been transported from distances of at least 300 km. author is grateful to the members of the Meteorite Working Group, National Science Foundation, and Lunar Curatorial Facility for having allocated the samples used in this study. Reviews by Christian Koeberl and Herbert Palme were constructive, thorough, and much appreciated during revision of the manuscript.
Preliminary Examination of Lunar Samples from Apollo 14
Science, 1971
A physical, chemical, mineralogical, and biolog analysis of 43 kilograms of lunar rocks and fi: The Lunar Sample Preliminary Examination Team The surface of the moon can be divided into the dark mare areas and the bright highland regions. The mare regions cover about one-third of the near side of the moon and make up a small fraction of the far side. These mare areas are recognized as the areas of most recent widespread rock formation on the lunar surface. The first three groups of samples returned from the moon to earth, that is, the samples from the Apollo 11, Apollo 12, jand Luna 16 missions, all come from typical mare regions. Detailed chemical and petrographic studies of the samples from the three widely separated mare regions show that the dark regions of the moon are probably underlain by basaltic rocks that are iron-rich and sodium-poor (relative to similar terrestrial rocks). Absolute ages determined for basaltic rocks from the Apollo 11 and Apollo 12 sites and crater densities on nearby mare surfaces suggest that the final filling of most mare basins took place between 3.0 X 109 and 4.0 X 109 years ago. The stratigraphic and petrographic studies of the mare samples lead to two general inferences regarding the moon: (i) that the internal temperatures of at least parts of the moon reached the melting point of basalt less than 1 x 109 years after the formation of the moon, and (ii) that the evolution of
Apollo 17 regolith, 71501,262: A record of impact events and mare volcanism in lunar glasses
Meteoritics & Planetary Science, 2009
Thirteen glasses from Apollo 17 regolith 71501,262 have been chemically analyzed by electron microprobe and isotopically dated with the 40 Ar/ 39 Ar dating method. We report here the first isotopic age obtained for the Apollo 17 very low titanium (VLT) volcanic glasses, 3630 ± 40 Ma. Twelve impact glasses that span a wide compositional range have been found to record ages ranging from 102 ± 20 Ma to 3740 ± 50 Ma. The compositions of these impact glasses show that some have been produced by impact events within the Apollo 17 region, whereas others appear to be exotic to the landing site. As the data sets that include compositions and ages of lunar impact glasses increase, the impact history in the Earth-Moon system will become better constrained.
2003
Phase equilibrium experiments on the most magnesian Apollo 15C green picritic glass composition indicate a multiple saturation point with olivine and orthopyroxene at 1520°C and 1.3 GPa (about 260 km depth in the moon). This composition has the highest Mg# of any lunar picritic glass and the shallowest multiple saturation point. Experiments on an Apollo 15A composition indicate a multiple saturation point with olivine and orthopyroxene at 1520°C and 2.2 GPa (about 440 km depth in the moon). The importance of the distinctive compositional trends of the Apollo 15 groups A, B, and C picritic glasses merits the reanalysis of NASA slide 15426,72 with modern electron microprobe techniques. We confirm the compositional trends reported by Delano (1979, 1986) in the major element oxides SiO 2 , TiO 2 , Al 2 O 3 , Cr 2 O 3 , FeO, MnO, MgO, and CaO, and we also obtained data for the trace elements P 2 O 5 , K 2 O, Na 2 O, NiO, S, Cu, Cl, Zn, and F. Petrogenetic modeling demonstrates that the Apollo 15 A-B-C glass trends could not have been formed by fractional crystallization or any continuous assimilation/fractional crystallization (AFC) process. The B and C glass compositional trends could not have been formed by batch or incremental melting of an olivine + orthopyroxene source or any other homogeneous source, though the A glasses may have been formed by congruent melting over a small pressure range at depth. The B compositional trend is well modeled by starting with an intermediate A composition and assimilating a shallower, melted cumulate, and the C compositional trend is well modeled by a second assimilation event. The assimilation process envisioned is one in which heat and mass transfer were separated in space and time. In an initial intrusive event, a picritic magma crystallized and provided heat to melt magma ocean cumulates. In a later replenishment event, the picritic magma incrementally mixed with the melted cumulate (creating the compositional trends in the green glass data set), ascended to the lunar surface, and erupted as a fire fountain. A barometer created from multiple saturation points provides a depth estimate of other glasses in the A-B-C trend and of the depths of assimilation. This barometer demonstrates that the Apollo 15 A-B-C trend originated over a depth range of ~460 km to ~260 km within the moon.
The geochemistry and provenance of Apollo 16 mafic glasses
Geochimica et Cosmochimica Acta, 2006
The regolith of the Apollo 16 lunar landing site is composed mainly of feldspathic lithologies but mafic lithologies are also present. A large proportion of the mafic material occurs as glass. We determined the major element composition of 280 mafic glasses (>10 wt% FeO) from six different Apollo 16 soil samples. A small proportion (5%) of the glasses are of volcanic origin with picritic compositions. Most, however, are of impact origin. Approximately half of the mafic impact glasses are of basaltic composition and half are of noritic composition with high concentrations of incompatible elements. A small fraction have compositions consistent with impact mixtures of mare material and material of the feldspathic highlands. On the basis of major-element chemistry, we identified six mafic glass groups: VLT picritic glass, low-Ti basaltic glass, high-Ti basaltic glass, high-Al basaltic glass, KREEPy glass, and basaltic-andesite glass. These glass groups encompass 60% of the total mafic glasses studied. Trace-element analyses by secondary ion mass spectroscopy for representative examples of each glass group (31 total analyses) support the major-element classifications and groupings. The lack of basaltic glass in Apollo 16 ancient regolith breccias, which provide snapshots of the Apollo 16 soil just after the infall of Imbrium ejecta, leads us to infer that most (if not all) of the basaltic glass was emplaced as ejecta from small-or moderate-sized impacts into the maria surrounding the Apollo 16 site after the Imbrium impact. The high-Ti basaltic glasses likely represent a new type of basalt from Mare Tranquillitatis, whereas the low-Ti and high-Al basaltic glasses possibly represent the composition of the basalts in Mare Nectaris. Both the low-Ti and high-Al basaltic glasses are enriched in light-REEs, which hints at the presence of a KREEP-bearing source region beneath Mare Nectaris. The basaltic andesite glasses have compositions that are siliceous, ferroan, alkali-rich, and moderately titaniferous; they are unlike any previously recognized lunar lithology or glass group. Their likely provenance is within the Procellarum KREEP Terrane, but they are not found within the Apollo 16 ancient regolith breccias and therefore were likely deposited at the Apollo 16 site post-Imbrium. The basaltic-andesite glasses are the most ferroan variety of KREEP yet discovered.
History of the Apollo 15 yellow impact glass and sample 15426 and 15427
Journal of Geophysical Research, 1984
Individual pieces of the Apollo 15 yellow impact glass from 15426 and 15427 were studied using the laser microprobe to determine their 39Ar-40Ar age and their 38Ar-37Ar exposure age. Except for the extractions from one fragment, the age determinations required significant correction for trapped 40Ar. Data from multiple extractions on each fragment were used to make individual 40Ar/36-Arsw versus 39ArK/36Ars._. plots from which the apparent age and trappe• component for each fragment was determined. An age of 3.35 +_ 0.05 AE was determined for the age of the impact event that formed these glasses. This age cannot be reconciled with the age prediction of Delano et al. [1982]. Since these glasses were probably produced by an impact into a target of moderate-TiO 2 basalts, and the only known moderate-TiO 2 basaltic flows are younger than the impact event [Boyce and Johnson, 1978], the target for these glasses must be covered up by later basaltic flows. The average 38Ar-37Ar exposure age for these glasses was 274 +_ 74 m.y. Other glasses from clods 15426 and 15427 give similar exposure ages [Spangler et al. 1984]. Two possible reasons for this similarity is that (1) the clods formed at greater than 300 m.y. ago so that all glasses in 15426 and 15427 shared a common exposure history, and (2) the gardening at Station 7 produced a soil with an average exposure age of-300 m.y. abundances of the large ion lithophile elements, and chondrite-normalized La/Lu and Sm/Eu ratios of 2.0 and 4.8, respectively [Delano et al., 1982; Taylor et al., 1980]. According to their texture, they are members of a class of impact glasses known as 'ropy glass' [Delano et al., 1982]. The existence of highlands material, mare material, Apollo 15 volcanic green glass, and Apollo 15 volcanic yellow glass [Delano et al., 1982] as clasts in the yellow glass fragments also suggests an impact origin. The glasses selected for this study contained no clasts, since the presence of any clasts would compromise the analysis and the age determina-Copyright 1984 by American Geophysical Union. Paper number 3B5015. 0148-0227 / 84/003B-5015505.00 B481 oo•oo ß ß ß ß ß ß oooooo +l +1 +l +l +l +l ß ß ß ß ß ß ß ß ß ß ß ß +1 +1 +1 +1 +1 +1 ß ß ß ß ß ß +1 +1 +1 +1 +l +1 ß ß ß ß ß +1 +l +1 +, +l +1 +1+1+1 +1 +l +1 +l+l+,+l +1 +l+,+l +1 +, +1 +1 +1 +, +, +,•• •o•• o••• oooooo +1 +1 +1 +1 +1 +1 ß ß ß ß ß ß oooooo