Impactite slag at Barringer Crater [Arizona]

Nininger, H. H.

doi:10.2475/ajs.252.5.277

Cited by 20 publications

(13 citation statements)

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“…1g,h). These morphologic observations corroborate those of Nininger (1954) and they identify these melt particles as ballistic ejecta. However, we do not agree with his classification of "impactites" and "accretionary lapilli", and suggest that this classification be abandoned.…”

Section: Morphology Of Melt Particlessupporting

confidence: 85%

“…The field observations by Nininger (1954) and subsequent workers, including us, suggest that all currently existing melts are volumetrically trivial relative to the total ejecta. While this field observation does not specify melt depth, it does argue for a small melt volume.…”

Section: --------:~:--------/:--------:+:--------mentioning

confidence: 72%

“…This intense mixing must occur during the early stages of the cratering process because it is substantially complete prior to ballistic ejection based on the chemically homogeneous melt bombs of the Ries and other terrestrial craters (e.g., Engelhardt, 1997;See et al, 1998;Masaitis et al, 1999). For most craters, it is not possible to reconstruct the pre-impact stratigraphy with sufficient The first descriptions of the melts from Meteor Crater are by Nininger (1954Nininger ( , 1956, who details their field occurrence, the diverse morphologies, their chemical bulk composition, and who first identified them as ballistically transported melt-spray. Most subsequent compositional studies of these melts addressed the dissemination of the iron-meteorite projectile (Morgan et al, 1975), or chemical fractionation of the projectile during impact-induced melting (e.g., Brett, 1967;Kelly et al, 1974).…”

Section: Introductionmentioning

confidence: 99%

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Petrographic studies of the impact melts from Meteor Crater, Arizona, USA

Hörz

Mittlefehldt

See

et al. 2002

Meteorit & Planetary Scien

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Abstract-We investigated the ballistically dispersed melts from Meteor Crater, Arizona, USA to determine the stratigraphic extent of its melt zone from the compositional relationship of melts and target rocks. Most melt particles are crystallized, hydrated, and oxidized; pristine glasses are rare. Hydration and oxidation occurred at ambient temperatures long after the impact. The preserved glasses are generally clear and texturally homogeneous, but unlike typical impact melts, they have unusually heterogeneous compositions, both within individual particles and from sample to sample. For example, the average Si0 2 for individual particles ranges from 43 to 65%. The projectile content is unusually high and it is distributed bimodally, with specific samples containing either 5-10% or 20-30% FeO. These compositional heterogeneities most likely reflect the high carbonate content of the target rocks and the release of copious COz that dispersed the melts, thereby terminating melt flow and mixing. The high projectile content and the COz depleted residue of purely sedimentary rocks produced mafic melts that crystallized fine-grained olivine and pyroxene.The melts fall into three compositional groups reflecting variable proportions of the major target formations, Moenkopi, Kaibab, and Coconino. Least-square mixing calculations revealed one group to contain 55% Moenkopi, 40% quartz-rich, upper Kaibab, and 5% meteorite, suggesting a source depth of <30 m from the pre-impact surface. The other two melt groups have higher contents of meteorite (15-20%) and Kaibab (50-70%) and contain more SiOz than average Kaibab. The additional quartz may have been derived from Coconino or the upper Kaibab, implying melt depths >90 m or <30 m, respectively. Additional studies, especially hydrocode calculations, are needed to better understand the source depth ofthese melts and their exceptionally high projectile content.

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Section: Morphology Of Melt Particlessupporting

confidence: 85%

Section: --------:~:--------/:--------:+:--------mentioning

confidence: 72%

Section: Introductionmentioning

confidence: 99%

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Petrographic studies of the impact melts from Meteor Crater, Arizona, USA

Hörz

Mittlefehldt

See

et al. 2002

Meteorit & Planetary Scien

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“…Metallic particles in impactites: Originally, the name "impactites" was adopted to define silica-glass slag, mostly in the form of little bombs, found in association with impact structures (Spencer 1933). Nininger started to look for similar products around Meteor Crater and quickly found them all around the crater in the form of small, micron-to mm-size bombs in coincidence with metallic spheroids and sluglets (Nininger 1954(Nininger , 1956. He estimated that in the most heavily impregnated horizon, the amount of this slag ranged around 30 to 100 kg/m 3 .…”

Section: The Fate Of the Impactor-findings And Geochemistrymentioning

confidence: 99%

The Canyon Diablo impact event: Projectile motion through the atmosphere

Artemieva

Pierazzo

2009

Meteorit & Planetary Scien

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Abstract-Meteor Crater is one of the first impact structures systematically studied on Earth. Its location in arid northern Arizona has been ideal for the preservation of the structure and the surviving meteoric material. The recovery of a large amount of meteoritic material in and around the crater has allowed a rough reconstruction of the impact event: an iron object 50 m in diameter impacted the Earth's surface after breaking up in the atmosphere. The details of the disruption, however, are still debated. The final crater morphology (deep, bowl-shaped crater) rules out the formation of the crater by an open or dispersed swarm of fragments, in which the ratio of swarm radius to initial projectile radius C d is larger than 3 (the final crater results from the sum of the craters formed by individual fragments). On the other hand, the lack of significant impact melt in the crater has been used to suggest that the impactor was slowed down to 12 km/s by the atmosphere, implying significant fragmentation and fragments' separation up to 4 initial radii. This paper focuses on the problem of entry and motion through the atmosphere for a possible Canyon Diablo impactor as a first but necessary step for constraining the initial conditions of the impact event which created Meteor Crater.After evaluating typical models used to investigate meteoroid disruption, such as the pancake and separated fragment models, we have carried out a series of hydrodynamic simulations using the 3D code SOVA to model the impactor flight through the atmosphere, both as a continuum object and a disrupted swarm.Our results indicate that the most probable pre-atmospheric mass of the Meteor Crater projectile was in the range of 4⋅10 8 to 1.2⋅10 9 kg (equivalent to a sphere 46-66 m in diameter). During the entry process the projectile lost probably 30% to 70% of its mass, mainly because of mechanical ablation and gross fragmentation. Even in the case of a tight swarm of particles (C d <3), small fragments can separate from the crater-forming swarm and land on the plains (tens of km away from the crater) as individual meteorites. Starting from an impactor pre-atmospheric velocity of ~18 km/s, which represents an average value for Earth-crossing asteroids, we find that after disruption, the most probable impact velocity at the Earth's surface for a tight swarm is around 15 km/s or higher. A highly dispersed swarm would result in a much stronger deceleration of the fragments but would produce a final crater much shallower than observed at Meteor Crater.

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“…Such impact-melted material has been found in several forms, both around the resulting crater and in the breccias deposited within it: (1) individual bodies composed of n ►ixtures of glass and rock and mineral fragments, which are ejected from the crater and aerodynamically shaped before deposition. The impactite of Meteor Crater, Arizona (Nininger, 1954) and the Fladen of the Ries, Germany (Horz, 1965) are examples.…”

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confidence: 99%

Possible relations between meteorite impact and igneous petrogenesis, as indicated by the Sudbury structure, Ontario, Canada

French

1970

Bull Volcanol

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Impactite slag at Barringer Crater [Arizona]

Cited by 20 publications

References 0 publications

Petrographic studies of the impact melts from Meteor Crater, Arizona, USA

Petrographic studies of the impact melts from Meteor Crater, Arizona, USA

The Canyon Diablo impact event: Projectile motion through the atmosphere

Possible relations between meteorite impact and igneous petrogenesis, as indicated by the Sudbury structure, Ontario, Canada

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