English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Zendy Open

Presents the pdf analysis as premium feature

PDF Analysis

Insights

Presents the summarisation as premium feature

Summarisation

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

The terrestrial record of meteorite impacts is difficult to decipher because unequivocal evidenceof impact is increasingly destroyed with time by erosion, burial, and tectonics. Zirconsurvives these processes as a shocked mineral, and above 20 GPa transforms to reidite, a high-pressureZrSiO 4 polymorph diagnostic of impact. However, the utility of reidite has been limitedby its occurrence; it has only been reported from three relatively young (<36 Ma) impactcraters globally. Here we report a new occurrence of reidite in brecciated sandstone from theOrdovician Rock Elm impact crater in Wisconsin, United States. Electron backscatter diffractionmapping was used to identify reidite and microtwins within shocked zircons smallerthan 50 μm in diameter. Reidite occurs both as 200–500-nm-wide lamellar intergrowths andas nanoparticulate grains, and not only provides the first diagnostic evidence for ultrahigh-pressureshock metamorphism at Rock Elm, but is also the oldest reported occurrence ofreidite. Considering its small size, and the ubiquitous presence of detrital zircon in siliciclasticrocks, reidite may be more common in the rock record than has been reported but haspotentially gone undetected. The recognition that nanoscale reidite can be preserved over deeptime within zircon in shock-metamorphosed sandstone presents new opportunities for investigatingEarth9s impact record, as it could potentially preserve nanoscopic evidence of impactevents much older than the one that formed Rock Elm. Given that shocked zircons have beenshown to survive sedimentary cycling, the identification of reidite within zircons in siliciclasticrocks could facilitate investigating the impact chronology over much of the geological timescale, as the oldest terrestrial minerals known are detrital zircons.

Nanoscale records of ancient shock deformation: Reidite (ZrSiO4) in sandstone at the Ordovician Rock Elm impact crater