The Saricicek howardite fall in Turkey: Source crater of HED meteorites on Vesta and impact risk of Vestoids


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Unsalan O. , Jenniskens P., YIN Q., Kaygisiz E., ALBERS J., CLARK D. L. , ...Daha Fazla

METEORITICS & PLANETARY SCIENCE, cilt.54, ss.953-1008, 2019 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 54 Konu: 5
  • Basım Tarihi: 2019
  • Doi Numarası: 10.1111/maps.13258
  • Dergi Adı: METEORITICS & PLANETARY SCIENCE
  • Sayfa Sayıları: ss.953-1008

Özet

The Saricicek howardite meteorite shower consisting of 343 documented stones
occurred on September 2, 2015 in Turkey and is the first documented howardite fall.
Cosmogenic isotopes show that Saricicek experienced a complex cosmic-ray exposure history,
exposed during ~12–14 Ma in a regolith near the surface of a parent asteroid, and that an
~1 m sized meteoroid was launched by an impact 22  2 Ma ago to Earth (as did one-third
of all HED meteorites). SIMS dating of zircon and baddeleyite yielded 4550.4  2.5 Ma and
4553  8.8 Ma crystallization ages for the basaltic magma clasts. The apatite U-Pb age of
4525  17 Ma, K-Ar age of ~3.9 Ga, and the U,Th-He ages of 1.8  0.7 and 2.6  0.3 Ga
are interpreted to represent thermal metamorphic and impact-related resetting ages,
respectively. Petrographic; geochemical; and O-, Cr-, and Ti-isotopic studies confirm that
Saricicek belongs to the normal clan of HED meteorites. Petrographic observations and
analysis of organic material indicate a small portion of carbonaceous chondrite material in
the Saricicek regolith and organic contamination of the meteorite after a few days on soil.
Video observations of the fall show an atmospheric entry at 17.3  0.8 km s
1 from NW;
fragmentations at 37, 33, 31, and 27 km altitude; and provide a pre-atmospheric orbit that is
the first dynamical link between the normal HED meteorite clan and the inner Main Belt.
Spectral data indicate the similarity of Saricicek with the Vesta asteroid family (V-class)
spectra, a group of asteroids stretching to delivery resonances, which includes (4) Vesta.
Dynamical modeling of meteoroid delivery to Earth shows that the complete disruption of a
~1 km sized Vesta family asteroid or a ~10 km sized impact crater on Vesta is required to
provide sufficient meteoroids ≤4 m in size to account for the influx of meteorites from this
HED clan. The 16.7 km diameter Antionia impact crater on Vesta was formed on terrain of
the same age as given by the 4He retention age of Saricicek. Lunar scaling for crater
production to crater counts of its ejecta blanket show it was formed ~22 Ma ago.