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

Peng, Ming; Aggrey, Kwesi E.; Tonzola, C.; Schnabel, C.; Nicola, Pizzeghello; Herzog, G. F.; Wasson, J. T.; Glass, B. P.; Brown, Leanne; Tera, F.; Middleton, R.; Klein, J.

doi:10.1016/j.gca.2004.03.026

Cited by 75 publications

(85 citation statements)

References 56 publications

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“…These sites are closer to the more recently proposed locations for the source crater of the Australasian tektite/microtektite strewn field (e.g., Schnetzler 1992;Ma et al 2004) than are previously studied Australasian microtektite-bearing core sites. Thus, we believed that the study of the microtektites and unmelted ejecta in these cores would give us a clearer understanding of the nature of the target rocks and location of the source crater for the Australasian strewn field.…”

Section: Introductionsupporting

confidence: 68%

“…10). The southeast part of this region overlaps the area in the Gulf of Tonkin, where Australasian tektites with low 10 Be contents have been found and which Ma et al (2004) suggested as a possible location of the Australasian tektite source crater.…”

Section: Location and Size Of The Source Cratermentioning

confidence: 77%

“…The size, shape, and mineral assemblage of inclusions found in layered, or Muong Nongtype, tektites from Indochina also indicate a sedimentary source rock and suggest that it was fine-grained (Glass and Barlow 1979). Beryllium-10 studies suggest that the Australasian tektites were derived from surface or nearsurface sedimentary deposits (Pal et al 1982;Blum et al 1992;Ma et al 2004). Blum et al (1992) interpreted Sr isotopic data as indicating the source rock was Jurassic in age and proposed that the Australasian tektites may have been derived from Jurassic formations consisting of sandstone and conglomerate with interlayered micaceous shale and siltstone.…”

Section: Introductionmentioning

confidence: 97%

“…Most investigators have concluded that the impact that produced the Australasian tektites took place somewhere in Indochina, but the source crater is still unknown (Stauffer 1978;Ford 1988;Schnetzler et al 1988;Schnetzler 1992;Hartung and Koeberl 1994;Glass and Pizzuto 1994;Koeberl 1994;Lee and Wei 2000;Glass 2003;Ma et al 2004).…”

Section: Introductionmentioning

confidence: 99%

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Australasian microtektites and associated impact ejecta in the South China Sea and the Middle Pleistocene supereruption of Toba

Glass

Koeberl

2006

Meteorit & Planetary Scien

113

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Abstract-Australasian microtektites were discovered in Ocean Drilling Program (ODP) Hole 1143A in the central part of the South China Sea. Unmelted ejecta were found associated with the microtektites at this site and with Australasian microtektites in Core SO95-17957-2 and ODP Hole 1144A from the central and northern part of the South China Sea, respectively. A few opaque, irregular, rounded, partly melted particles containing highly fractured mineral inclusions (generally quartz and some K feldspar) and some partially melted mineral grains, in a glassy matrix were also found in the microtektite layer. The unmelted ejecta at all three sites include abundant white, opaque grains consisting of mixtures of quartz, coesite, and stishovite, and abundant rock fragments which also contain coesite and, rarely, stishovite. This is the first time that shock-metamorphosed rock fragments have been found in the Australasian microtektite layer. The rock fragments have major and trace element contents similar to the Australasian microtektites and tektites, except for higher volatile element contents. Assuming that the Australasian tektites and microtektites were formed from the same target material as the rock fragments, the parent material for the Australasian tektites and microtektites appears to have been a fine-grained sedimentary deposit. Hole 1144A has the highest abundance of microtektites (number/cm 2 ) of any known Australasian microtektite-bearing site and may be closer to the source crater than any previously identified Australasian microtektite-bearing site. A source crater in the vicinity of 22° N and 104° E seems to explain geographic variations in abundance of both the microtektites and the unmelted ejecta the best; however, a region extending NW into southern China and SE into the Gulf of Tonkin explains the geographic variation in abundance of microtektites and unmelted ejecta almost as well. The size of the source crater is estimated to be 43 ± 9 km based on estimated thickness of the ejecta layer at each site and distance from the proposed source. A volcanic ash layer occurs just above the Australasian microtektite layer, which some authors suggest is from a supereruption of the Toba caldera complex. We estimate that deposition of the ash occurred ∼800 ka ago and that it is spread over an area of at least 3.7 × 10 7 km 2 .

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Section: Introductionsupporting

confidence: 68%

Section: Location and Size Of The Source Cratermentioning

confidence: 77%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Australasian microtektites and associated impact ejecta in the South China Sea and the Middle Pleistocene supereruption of Toba

Glass

Koeberl

2006

Meteorit & Planetary Scien

113

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“…Which of these scenarios is applicable cannot be decided from the present data alone. However, the target stratigraphy at Chicxulub indicates that the source rocks from which the Beloc black impact glasses were derived (and with which they show geochemical similarities; e.g., Blum et al 1993) were not close to the surface at the time of the impact, while tektites in the Cenozoic strewn field were derived from near-surface material (e.g., Ma et al 2004). Explosive decomposition of the overlying carbonate and evaporite rocks may have created zones of widely varying oxygen fugacities.…”

Section: Discussionmentioning

confidence: 99%

Iron oxidation state in impact glass from the K/T boundary at Beloc, Haiti, by high-resolution XANES spectroscopy

Giuli

Eeckhout

Paris

et al. 2005

Meteoritics &Amp; Planetary Science

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Abstract-We examined the local iron environment in nine impact glasses from the CretaceousTertiary (K/T) boundary section at Beloc, Haiti, which formed as the result of impact melting during the Chicxulub impact event. The samples have been analyzed by Fe K-edge high-resolution X-ray absorption near edge structure (XANES) spectroscopy to obtain data on both the Fe oxidation state and the coordination number. The pre-edge peak of our high-resolution XANES spectra display noticeable variations indicative of significant changes in the Fe oxidation state spanning a wide range from about 20 to 75 mol% trivalent Fe. All data plot along the same trend, falling between two mixing lines joining a point calculated as the mean of a group of tektites studied so far (consisting of four-and five-coordinated Fe 2+ ) to [4] Fe 3+ and [5] Fe 3+ , respectively. Thus, the XANES spectra can be interpreted as a mixture of [4] Fe 2+ , [5] Fe 2+ , [4] Fe 3+ , and [5] Fe 3+ . There is no evidence for six-fold coordinated Fe; however, its presence in small amounts cannot be excluded from XANES data alone. Our observations can be explained by two possible scenarios: either these impact glasses formed under very reducing conditions and, because of their small size, were easily oxidized in air while still molten, or they formed under a variety of different oxygen fugacities resulting in different Fe oxidation states. In the first case, the oxidation state and coordination number would imply similar formation conditions as splash-form tektites, followed by progressive oxidation.

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Morphological and Chemical Properties of Microtektite Grains from Bay of Bengal (IODP Expedition 354)

Kawsar

Manoj²,

Yoshida

et al. 2020

Dynamics of the Earth System: Evolution, Processes and Interactions

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

Cited by 75 publications

References 56 publications

Australasian microtektites and associated impact ejecta in the South China Sea and the Middle Pleistocene supereruption of Toba

Australasian microtektites and associated impact ejecta in the South China Sea and the Middle Pleistocene supereruption of Toba

Iron oxidation state in impact glass from the K/T boundary at Beloc, Haiti, by high-resolution XANES spectroscopy

Morphological and Chemical Properties of Microtektite Grains from Bay of Bengal (IODP Expedition 354)

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