Abu Hureyra, Syria, Part 1: Shock-fractured quartz grains support 12,800-year-old cosmic airburst at the Younger Dryas onset

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11310%2F23%3A10476072" target="_blank" >RIV/00216208:11310/23:10476072 - isvavai.cz</a>

Výsledek na webu

<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=8U6W78Hd-F" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=8U6W78Hd-F</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.14293/ACI.2023.0003" target="_blank" >10.14293/ACI.2023.0003</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Abu Hureyra, Syria, Part 1: Shock-fractured quartz grains support 12,800-year-old cosmic airburst at the Younger Dryas onset

Popis výsledku v původním jazyce

A previous investigation revealed that shock-fracturing, a form of low-pressure shock metamorphism in quartz grains, can be produced during near-surface atomic airbursts and in cosmic impact structures, most likely at pressures lower than 8 GPa. This discovery implies that similar shock-fracturing may also form in quartz grains exposed to near-surface airbursts by comets and asteroids. Here, we investigate this hypothesis by examining quartz grains in a sedimentary profile from Abu Hureyra, a prehistoric archaeological site in northern Syria. This site was previously proposed to have experienced a nearby, low-altitude cosmic airburst at the onset of the Younger Dryas (~12,800 years ago). The Younger Dryas boundary layer (YDB) at Abu Hureyra has previously been shown to contain a rich assemblage of materials consistent in indicating a cosmic impact. These include anomalously high concentrations of melted micro-spherules displaying increased remanent magnetism; meltglass with low water content indicative of high-temperature melting; nanodiamonds, potentially including lonsdaleite; carbon spherules produced by biomass burning; black carbon or soot; total organic carbon; and abnormally high-temperature melted refractory minerals and elements, including platinum, iridium, chromite, and zircon. To further test this impact hypothesis, we searched for evidence of shocked quartz, a robust, widely accepted indicator of cosmic impacts. We used a comprehensive analytical suite of high-resolution techniques, including transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD), to examine and characterize quartz grains from the YDB layer at Abu Hureyra. Our analyses revealed the presence of quartz grains with sub-planar, sub-parallel, and sub-micron-wide intragranular fractures, most likely produced by mechanical and thermal shock or the combination of both. Furthermore, these fractures are typically filled with amorphous silica (glass), a classic indicator of shock metamorphism. Elemental analyses of the weight percentages of oxygen in the amorphous silica indicate that this could not have formed from the deposition of hydrated silica (e.g., opal and hyalite), which is enhanced in oxygen. Instead, the silica we observed is typically depleted in oxygen, consistent with melting under highly reducing conditions. The shock fractures in quartz grains also display Dauphiné twinning, which sometimes develops during the stress of high temperatures or pressures. This evidence is consistent with the hypothesis that the glass-filled fractures in quartz grains were produced by thermal and mechanical shock during a near-surface cosmic airburst at Abu Hureyra. These glass-filled fractures closely resemble those formed in near-surface atomic airbursts and crater-forming impact events.

Název v anglickém jazyce

Abu Hureyra, Syria, Part 1: Shock-fractured quartz grains support 12,800-year-old cosmic airburst at the Younger Dryas onset

Popis výsledku anglicky

A previous investigation revealed that shock-fracturing, a form of low-pressure shock metamorphism in quartz grains, can be produced during near-surface atomic airbursts and in cosmic impact structures, most likely at pressures lower than 8 GPa. This discovery implies that similar shock-fracturing may also form in quartz grains exposed to near-surface airbursts by comets and asteroids. Here, we investigate this hypothesis by examining quartz grains in a sedimentary profile from Abu Hureyra, a prehistoric archaeological site in northern Syria. This site was previously proposed to have experienced a nearby, low-altitude cosmic airburst at the onset of the Younger Dryas (~12,800 years ago). The Younger Dryas boundary layer (YDB) at Abu Hureyra has previously been shown to contain a rich assemblage of materials consistent in indicating a cosmic impact. These include anomalously high concentrations of melted micro-spherules displaying increased remanent magnetism; meltglass with low water content indicative of high-temperature melting; nanodiamonds, potentially including lonsdaleite; carbon spherules produced by biomass burning; black carbon or soot; total organic carbon; and abnormally high-temperature melted refractory minerals and elements, including platinum, iridium, chromite, and zircon. To further test this impact hypothesis, we searched for evidence of shocked quartz, a robust, widely accepted indicator of cosmic impacts. We used a comprehensive analytical suite of high-resolution techniques, including transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD), to examine and characterize quartz grains from the YDB layer at Abu Hureyra. Our analyses revealed the presence of quartz grains with sub-planar, sub-parallel, and sub-micron-wide intragranular fractures, most likely produced by mechanical and thermal shock or the combination of both. Furthermore, these fractures are typically filled with amorphous silica (glass), a classic indicator of shock metamorphism. Elemental analyses of the weight percentages of oxygen in the amorphous silica indicate that this could not have formed from the deposition of hydrated silica (e.g., opal and hyalite), which is enhanced in oxygen. Instead, the silica we observed is typically depleted in oxygen, consistent with melting under highly reducing conditions. The shock fractures in quartz grains also display Dauphiné twinning, which sometimes develops during the stress of high temperatures or pressures. This evidence is consistent with the hypothesis that the glass-filled fractures in quartz grains were produced by thermal and mechanical shock during a near-surface cosmic airburst at Abu Hureyra. These glass-filled fractures closely resemble those formed in near-surface atomic airbursts and crater-forming impact events.

Druh

J_ost - Ostatní články v recenzovaných periodicích

CEP obor

—

OECD FORD obor

10505 - Geology

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2023

Kód důvěrnosti údajů

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

Název periodika

Airbursts and Cratering Impacts

ISSN

2941-9085

e-ISSN

2941-9085

Svazek periodika

1

Číslo periodika v rámci svazku

1

Stát vydavatele periodika

DE - Spolková republika Německo

Počet stran výsledku

28

Strana od-do

20230002

Kód UT WoS článku

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EID výsledku v databázi Scopus

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