Geochemistry of impact glasses and target rocks from the Zhamanshin Impact Structure, Kazakhstan: Implications for mixing of target and impactor matter

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00025798%3A_____%2F16%3A00000042" target="_blank" >RIV/00025798:_____/16:00000042 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/67985831:_____/16:00461314 RIV/00216208:11310/16:10328116

Výsledek na webu

<a href="http://www.sciencedirect.com/science/journal/00167037/190" target="_blank" >http://www.sciencedirect.com/science/journal/00167037/190</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.gca.2016.06.031" target="_blank" >10.1016/j.gca.2016.06.031</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Geochemistry of impact glasses and target rocks from the Zhamanshin Impact Structure, Kazakhstan: Implications for mixing of target and impactor matter

Popis výsledku v původním jazyce

Internal structure and element chemistry including contents of highly siderophile elements (HSE) and Os isotope ratios have been studied in target rocks and impact glasses of the Zhamanshin impact. They can be subdivided into acidic types (irghizites; 69-76 wt.% SiO2), basic splashforms (53-56 wt.% SiO2), and highly inhomogeneous composites. A comparison with the target rocks shows that zhamanshinites and basic splash-forms have no detectable admixture of the projectile matter. In contrast, irghizites exhibit clear admixture of the projectile, which was incorporated by complex processes accompanied by strong element fractionations. Microscopy confirms that irghizites were formed by coalescence of smaller molten glass droplets sized typically below 1 mm. Irghizites exhibit significant enrichments in Ni, Co and Cr, whose concentrations are locally enriched in the rims of the original small droplets. A portion of these elements and also part of Fe and Mn and other elements were derived from the impactor, most likely a Ni-rich carbonaceous chondrite. The contents of HSE are low and strongly fractionated, with moderate depletions of Pt and Pd and strong depletions of other HSE with respect to chondritic element ratios. Osmium shows the strongest depletion, likely related to the presence of oxygen in the post-impact atmosphere causing strong Os loss through volatilization. The observed structural and microchemical features of irghizites are interpreted to reflect variable proportions of the uppermost target sediments and the projectile matter, with HSE element ratios influenced by evaporation and condensation processes, and differences in volatility of individual HSE elements and/or their compounds. Two possible pathways of incorporation of the projectile matter into the irghizites include either re-condensation of evaporated projectile matter on the surface of glass droplets, or incorporation of less chemically fractionated microparticles dispersed by the explosion.

Název v anglickém jazyce

Geochemistry of impact glasses and target rocks from the Zhamanshin Impact Structure, Kazakhstan: Implications for mixing of target and impactor matter

Popis výsledku anglicky

Internal structure and element chemistry including contents of highly siderophile elements (HSE) and Os isotope ratios have been studied in target rocks and impact glasses of the Zhamanshin impact. They can be subdivided into acidic types (irghizites; 69-76 wt.% SiO2), basic splashforms (53-56 wt.% SiO2), and highly inhomogeneous composites. A comparison with the target rocks shows that zhamanshinites and basic splash-forms have no detectable admixture of the projectile matter. In contrast, irghizites exhibit clear admixture of the projectile, which was incorporated by complex processes accompanied by strong element fractionations. Microscopy confirms that irghizites were formed by coalescence of smaller molten glass droplets sized typically below 1 mm. Irghizites exhibit significant enrichments in Ni, Co and Cr, whose concentrations are locally enriched in the rims of the original small droplets. A portion of these elements and also part of Fe and Mn and other elements were derived from the impactor, most likely a Ni-rich carbonaceous chondrite. The contents of HSE are low and strongly fractionated, with moderate depletions of Pt and Pd and strong depletions of other HSE with respect to chondritic element ratios. Osmium shows the strongest depletion, likely related to the presence of oxygen in the post-impact atmosphere causing strong Os loss through volatilization. The observed structural and microchemical features of irghizites are interpreted to reflect variable proportions of the uppermost target sediments and the projectile matter, with HSE element ratios influenced by evaporation and condensation processes, and differences in volatility of individual HSE elements and/or their compounds. Two possible pathways of incorporation of the projectile matter into the irghizites include either re-condensation of evaporated projectile matter on the surface of glass droplets, or incorporation of less chemically fractionated microparticles dispersed by the explosion.

Druh

J_x - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)

CEP obor

DD - Geochemie

OECD FORD obor

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Projekt

<a href="/cs/project/GA13-22351S" target="_blank" >GA13-22351S: Využití netradičních a tradičních izotopových systémů k identifikaci zdrojových materiálů a procesů vzniku vltavínů</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2016

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Geochimica et Cosmochimica Acta

ISSN

0016-7037

e-ISSN

—

Svazek periodika

190

Číslo periodika v rámci svazku

1 October

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

26

Strana od-do

239-264

Kód UT WoS článku

000388802600014

EID výsledku v databázi Scopus

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