10Be in Australasian microtektites compared to tektites: Size and geographic controls

Rochette, P.; Braucher, Régis; Folco, Luigi; Horng, C. S.; Aumaître, Georges; Bourlès, Didier; Keddadouche, Karim

doi:10.1130/g45038.1

Cited by 27 publications

(16 citation statements)

References 22 publications

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“…), which is also supported by the 10 Be data (Rochette et al. ). The impact event itself is dated at ~0.78 Ma (Schwarz et al.…”

Section: Discussionsupporting

confidence: 82%

“…; Rochette et al. ). The possible proportion of the meteoritic component estimated from the Cr, Ni, Co, and highly siderophile elements (HSE) concentrations can probably reach up to ~1% in the case of splash‐form AAT (SFAAT) or Muong Nong‐type AAT (MNAAT), but as much as 5% in the case of the most Ni‐rich AAT microtektites (Glass et al.…”

Section: Introductionmentioning

confidence: 97%

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Triple oxygen isotope composition of Australasian tektites

Žák

Skála

Pack³

et al. 2019

Meteorit & Planetary Scien

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Major and trace element analyses and triple oxygen isotope measurements were performed on 11 individual specimens of Australasian tektites (AAT) with exactly known field positions from Laos. The sample set was dominated by Muong Nong-type tektites (MNAAT), including separated layers of glass of different appearance and chemistry from four samples. This first larger set of oxygen isotope data of MNAAT revealed the d 18 O range 8.7 ≤ d 18 O ≤ 11.6& on VSMOW2 scale (12 analyses), only slightly wider than the previously reported range for splashform AAT. The D' 17 O values of MNAAT (À0.098 ≤ D' 17 O ≤ À0.069&; 12 analyses) and splashform AAT (À0.080 ≤ D' 17 O ≤ À0.068&; three analyses) are all in the range of data typical for terrestrial crustal rocks, with no mass-independent oxygen isotope fractionation (from impactor or from exchange with atmospheric O 2 ) being observed.

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“…), which is also supported by the 10 Be data (Rochette et al. ). The impact event itself is dated at ~0.78 Ma (Schwarz et al.…”

Section: Discussionsupporting

confidence: 82%

Section: Introductionmentioning

confidence: 97%

Triple oxygen isotope composition of Australasian tektites

Žák

Skála

Pack³

et al. 2019

Meteorit & Planetary Scien

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“…They also report M S up to 10 −3 Am 2 /kg. This indicates significant amount of ferromagnetic impurities, as confirmed by our observation that a significant part of large microtektite from the South China Sea we studied in [35] are attracted by a magnet and present a dark color.…”

Section: Strewnfieldsupporting

confidence: 81%

“…The origin of the observed dichotomy in magnetic properties and oxidation ratio between paramagnetic glasses (five tektite strewn-fields, Darwin glass and urengoites) and the other partly ferromagnetic impact glasses (from 17 different craters) call for a fundamental difference in formation processes. The source material of tektites, being at the Earth surface with significant soil or continental sediment component [35], should initially have a large Fe 3+ /Fe tot ratio. Various hypotheses were put forward in [9] to explain the reduction endured by tektites including the effect of very high temperature and pressure, degassing of sulfur or mixing with reducing material (e.g., carbon).…”

Section: Synthesismentioning

confidence: 99%

Magnetic Properties and Redox State of Impact Glasses: A Review and New Case Studies from Siberia

et al. 2019

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High velocity impacts produce melts that solidify as ejected or in-situ glasses. We provide a review of their peculiar magnetic properties, as well as a new detailed study of four glasses from Siberia: El’gygytgyn, Popigai, urengoites, and South-Ural glass (on a total of 24 different craters or strewn-fields). Two types of behavior appear: 1) purely paramagnetic with ferromagnetic impurities at most of the order of 10 ppm; this corresponds to the five tektite strewn-fields (including the new one from Belize), urengoites, and Darwin glass. Oxidation state, based in particular on X-ray spectroscopy, is mostly restricted to Fe2+; 2) variable and up to strong ferromagnetic component, up to the 1 wt % range, mostly due to substituted magnetite often in superparamagnetic state. Accordingly, bulk oxidation state is intermediate between Fe2+ and Fe3+, although metallic iron, hematite, and pyrrhotite are sometimes encountered. Various applications of these magnetic properties are reviewed in the field of paleomagnetism, magnetic anomalies, recognition of glass origin, and formation processes.

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“…In discussion of 10 Be in Australasian tektites and microtektites (AAT and MTK, respectively), Rochette et al (2018) rejected loess from their potential source materials. An argument of inconsistency with a target sedimentary sequence in which 10 Be content decreases with depth fails if the target was a loess/paleosol (LP) sequence constrained by proper stratigraphic position and column height.…”

mentioning

confidence: 99%