Meteoritic, lunar and lonar impact chondrules

Fredriksson, K.; Noonan, A. F.; Nelen, J.

doi:10.1007/bf00564647

Cited by 42 publications

(18 citation statements)

References 18 publications

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“…La Fond and Dietz, 1964;Nayak, 1972Nayak, , 1993Fredriksson et al, 1973bFredriksson et al, , 1979Fudali et al, 1980). The history of the earlier studies is summarized in La Fond and Dietz (1964) and Fudali (1999) and included early work by Newbold (1844), Blandford (1868) and Medicott and Blanford (1879), who considered a cryptovolcanic origin (e.g.…”

Section: Lonar Cratermentioning

confidence: 99%

Comparison of Simple Impact Craters: A Case Study of Meteor and Lonar Craters

et al. 2012

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Section: Lonar Cratermentioning

confidence: 99%

Comparison of Simple Impact Craters: A Case Study of Meteor and Lonar Craters

et al. 2012

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“…The texture and mineralogy of 313A (Fig. 5 ) resembles that of a large (-0.9 mm in diameter) CLS olivine microporphyry in soil 6481 1 illustrated by Nelen et al Fredriksson et al (1973). Sample CLS 3 13A also has a texture similar to a small (-0.1 mm in diameter) olivine-rich microporphyry in breccia 65095 illustrated by Symes et al (1998b), except that the latter object has a more crystalline groundmass (Symes, pers.…”

Section: Olivine-rich Crystal-bearing Lunar Spherulesmentioning

confidence: 99%

“…These objects, termed crystal-bearing lunar spherules (CLSs), have textures suggestive of crystallization from freely-floating melt droplets and are found mainly in samples of highlands materials (e.g., King et al, 1972a,b;Nelen et al, 1972;Kurat et al, 1972bKurat et al, , 1974Fredriksson et al, 1973;Roedder and Weiblen, 1977). However, much of the previous research on CLSs was of a preliminary nature and done at a time when far less was known about the Moon and meteorite parent bodies.…”

Section: Introductionmentioning

confidence: 99%

Crystal‐bearing lunar spherules: Impact melting of the Moon's crust and implications for the origin of meteoritic chondrules

Ruzicka

Snyder

Taylor

2000

Meteorit & Planetary Scien

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Abstract-Crystal-bearing lunar spherules (CLSs) in lunar breccia (143 13, 143 15, 143 18), soil (68001, 241 OS), and impact-melt rock (62295) samples can be classified into two types: feldspathic and olivine-rich. Feldspathic CLSs contain equant, tabular, or acicular plagioclase grains set in glass or a pyroxene-olivine mesostasis; the less common olivine-rich CLSs contain euhedral or skeletal olivine set in glass, or possess a barred-olivine texture. Bulk-chemical and mineral-chemical data strongly suggest that feldspathic CLSs formed by impact melting of mixtures of ferroan anorthosite and Mg-suite rocks that compose the feldspathic crust of the Moon. It is probable that olivine-rich CLSs also formed by impact melting, but some appear to have been derived from distinctively magnesian lunar materials, atypical of the Moon's crust.Some CLSs contain reversely-zoned "relic" plagioclase grains that were not entirely melted during CLS formation, thin (25 p m thick) rims of troilite or phosphate, and chemical gradients in glassy mesostases attributed to metasomatism in a volatile-rich (Na-K-P-rich) environment. Crystal-bearing lunar spherules were rimmed and metasomatized prior to brecciation. Compound CLS objects are also present; these formed by lowvelocity collisions in an environment, probably an ejecta plume, that contained numerous melt droplets.Factors other than composition were responsible for producing the crystallinity of the CLSs. We agree with previous workers that relatively slow cooling rates and long ballistic travel times were critical features that enabled these impact-melt droplets to partially or completely crystallize in free-flight. Moreover, incomplete melting of precursor materials formed nucleation sites that aided subsequent crystallization.Clearly, CLSs do not resemble meteoritic chondrules in all ways. The two types of objects had different precursors and did not experience identical rimming processes, and vapor fractionation appears to have played a less important role in establishing the compositions of CLSs than of chondrules. However, the many detailed similarities between CLSs and chondrules indicate that it is more difficult to rule out an origin for some chondrules by impact melting than some have previously argued. Differences between CLSs, chondrules, and their host rocks possibly can be reconciled with an impact-melt origin for some chondrules when different precursors, the higher gravity of the Moon compared to chondrite parent bodies, and the likely presence of nebular gas during chondrule formation are taken into account.

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“…THE advantages of polished ultra-thin sections (PUTS) in the study of very fine-grained materials, such as occur in some meteorites, have been illustrated by Fredriksson et al (1978) whose technique is based on the earlier work of Beauchamp and WiUiford (1974). An essential feature of such methods for friable and heterogeneous materials is the use of a medium, usually an epoxy resin, to consolidate and partially impregnate them.…”

Section: Demountable Polished Extra-thin Sections and Their Use In Trmentioning

confidence: 99%

“…PUTS would be ideal starting material, therefore, and they would have the additional merit that the comparison of lightoptical and electron-optical observations would be greatly facilitated. Acknowledging this fact, but accepting that PUTS, as prepared by Fredriksson et al (1978), cannot be removed from the supporting glass slide for ion-thinning, a technique has been evolved for the preparation of demountable thin sections much less than 30 microns thick. For meteorites, which have been the materials of chief concern, th~ final thicknesses are typically 5-8 microns and the sections are hereafter referred to as DETS (demountable extra-thin sections).…”

Section: Demountable Polished Extra-thin Sections and Their Use In Trmentioning

confidence: 99%

Demountable polished extra-thin sections and their use in transmission electron microscopy

Barber

1981

Mineral. mag.

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The advantages of polished ultra-thin sections (PUTS) in the study of very fine-grained materials, such as occur in some meteorites, have been illustrated by Fredriksson et al. (1978) whose technique is based on the earlier work of Beauchamp and WiUiford (1974). An essential feature of such methods for friable and heterogeneous materials is the use of a medium, usually an epoxy resin, to consolidate and partially impregnate them. Normally one polished side of the specimen is bonded to a glass slide during preparation, and the finished PUTS are integral with the slide on completion. PUTS are typically 2-5 microns in thickness.

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Meteoritic, lunar and lonar impact chondrules

Cited by 42 publications

References 18 publications

Comparison of Simple Impact Craters: A Case Study of Meteor and Lonar Craters

Comparison of Simple Impact Craters: A Case Study of Meteor and Lonar Craters

Crystal‐bearing lunar spherules: Impact melting of the Moon's crust and implications for the origin of meteoritic chondrules

Demountable polished extra-thin sections and their use in transmission electron microscopy

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