10Be in irghizite tektites and zhamanshinite impact glasses

Raisbeck, G. M.; Yiou, F.; Zhou, Shubin; Koeberl, C.

doi:10.1016/0009-2541(88)90540-2

Cited by 9 publications

(5 citation statements)

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“…Tera et al (1983a, b, and c) and Klein and Middleton (1984) extended the work of Pal et al (1982). They observed that the 10 Be concentrations of Australasian tektites tend to increase with increasing distance from Southeast Asia (see also Raisbeck et al, 1988). For several reasons we thought that this trend deserved more detailed study.…”

Section: Introductionmentioning

confidence: 72%

Beryllium-10 in Australasian tektites: Constraints on the location of the source crater

Peng

Aggrey

Tonzola

et al. 2004

Geochimica et Cosmochimica Acta

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Section: Introductionmentioning

confidence: 72%

Beryllium-10 in Australasian tektites: Constraints on the location of the source crater

Peng

Aggrey

Tonzola

et al. 2004

Geochimica et Cosmochimica Acta

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“…Because of the 1.5 Ma half-lie of l0 Be, the concentrations in moldavites and North American tektites have dropped below a measurable level. However, the finding of 10 Be is not confined to Australasian tektites, but has also been found in Ivory Coast tektites, and the evaluation of other impact glasses (e.g., Aouelloul) has confirmed the interpretation of the target stratigraphy (Tera et al, 1983a(Tera et al, , 1983bRaisbeck et al, 1988). The absolute concentrations of 10 Be in the various types of Australasian tektites allow another important conclusion.…”

Section: Be-10 and The Target Stratigraphymentioning

confidence: 80%

“…The absolute concentrations of 10 Be in the various types of Australasian tektites allow another important conclusion. The 10 Be concentrations in australites are higher than those in indochinites and philippinites, which, in turn, are higher than those in Muong Nong-type tektites (Tera et al, 1983a(Tera et al, , 1983bPal et al, 1982;Raisbeck et al, 1988;J. Klein, 1992;personal communication).…”

Section: Be-10 and The Target Stratigraphymentioning

confidence: 98%

Tektite origin by hypervelocity asteroidal or cometary impact: Target rocks, source craters, and mechanisms

Koeberl¹

1992

Geological Society of America Special Papers

123

164

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Tektites are natural glasses that occur on earth in four distinct strewn fields (North American, Central European, Ivory Coast, and Australasian). Geochemical arguments have shown that tektites have been derived by hypervelocity impact melting from terrestrial upper crustal rocks, most likely sediments. The contents of Be-10 in tektites are evidence for a derivation of tektites from surface rocks, thus precluding an origin from greater depth in the crater. For two of the four tektite strewn fields (Ivory Coast, Central European), a possible connection to impact craters (Bosumtwi, and Ries, respectively) has been suggested on the basis of chemical, isotopic, and age data. No clear crater identifications have been made for the North American or Australasian strewn fields, although there are good candidates for both. Even though the geochemistry of tektites is in unequivocal favor of an origin by impact melting of terrestrial rocks, the unambiguous demonstration of the presence of an extraterrestrial contribution to the chemistry of tektites remains a problem. However, recent osmium isotope studies have shown that there is a clear meteoritic signature in at least some tektites. The exact mechanism of tektite formation is still not obvious, although some facts become increasingly clear. Tektite production requires specific impact conditions-otherwise there would be many more tektite strewn fields connected to the 150 or so known impact craters. Tektites are produced by nonequilibrium shock melting of surficial rocks, and the superheated melt may be subjected to a plasma phase during which they are subjected to partial reduction. They are then lofted through the atmosphere (probably in the wake of the expanding vapor cloud), quenched, and distributed over a geographically extended area-the strewn field. Some tektites solidify in a near-vacuum and re-enter the atmosphere. During the re-entry they melt again and form ablation-shaped tektites. Larger tektites, from a lower part of the target stratigraphy, are only distributed closer to the source crater. Many of them are more inhomogeneous melts and show a layered structure; they are called Muong Nong-type tektites. The study of tektites and the identification of possible new strewn fields provide important contributions toward the understanding of impact cratering.

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“…The difference in chemical composition between irghizites and basic splash forms reflects differences in the composition of target materials in Zhamanshin area 28 . Basic splash forms sampled deeper-seated lithologies such as andesitic volcanic rocks and basement tuffs, while irghizites were formed from surface sands and clays 27 , 28 , 72 , evidenced also by distinct Sr–Nd isotope systematics 64 and cosmogenic 10 Be identified solely in the irghizites, which suggests sampling of surface material 73 . This provides unequivocal evidence for the depth segregation limiting the interaction between impactor and target rocks for Zhamanshin impact materials but does not explain the difference in Δ 17 O between basic splash forms and irghizites (Fig.…”

Section: Discussionmentioning

confidence: 99%

Zhamanshin astrobleme provides evidence for carbonaceous chondrite and post-impact exchange between ejecta and Earth’s atmosphere

Magna

Žák

Pack³

et al. 2017

Nat Commun

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Chemical fingerprints of impacts are usually compromised by extreme conditions in the impact plume, and the contribution of projectile matter to impactites does not often exceed a fraction of per cent. Here we use chromium and oxygen isotopes to identify the impactor and impact-plume processes for Zhamanshin astrobleme, Kazakhstan. ε54Cr values up to 1.54 in irghizites, part of the fallback ejecta, represent the 54Cr-rich extremity of the Solar System range and suggest a CI-like chondrite impactor. Δ17O values as low as −0.22‰ in irghizites, however, are incompatible with a CI-like impactor. We suggest that the observed 17O depletion in irghizites relative to the terrestrial range is caused by partial isotope exchange with atmospheric oxygen (Δ17O = −0.47‰) following material ejection. In contrast, combined Δ17O–ε54Cr data for central European tektites (distal ejecta) fall into the terrestrial range and neither impactor fingerprint nor oxygen isotope exchange with the atmosphere are indicated.

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10Be in irghizite tektites and zhamanshinite impact glasses

Cited by 9 publications

References 0 publications

Beryllium-10 in Australasian tektites: Constraints on the location of the source crater

Beryllium-10 in Australasian tektites: Constraints on the location of the source crater

Tektite origin by hypervelocity asteroidal or cometary impact: Target rocks, source craters, and mechanisms

Zhamanshin astrobleme provides evidence for carbonaceous chondrite and post-impact exchange between ejecta and Earth’s atmosphere

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