Ordovician meteor event

Paleogeography of the Middle Ordovician (~470 Ma)^{[citation needed]}

The Ordovician meteor event was a dramatic increase in the rate at which L chondrite meteorites fell to Earth during the Middle Ordovician period, about 467.5±0.28 million years ago.^[1]^[2] This is indicated by abundant fossil L chondrite meteorites in a quarry in Sweden and enhanced concentrations of ordinary chondritic chromite grains in sedimentary rocks from this time.^[1]^[3]^[4]^[5]^[6]

According to a 2019 study, this temporary increase in the impact rate could have been caused by the destruction of the L chondrite parent body that was 150 kilometers (93 mi) in diameter and orbited in the asteroid belt between Mars and Jupiter.^[7] This occurred around 468 ± 0.3 million years ago having scattered fragments into Earth-crossing orbits, a chronology which is also supported by shock ages in numerous L chondrite meteorites that fall to Earth today.^[8]

It has been speculated that this influx contributed to, or possibly even instigated, the Great Ordovician Biodiversification Event, although this has been questioned.^[1]^[2]^[8]^[9]

A 2024 study found that all of 21 studied craters from this event were at the time within 30° of the equator. Impactors directly from the asteroid belt would be expected to produce a random distribution of craters, so this suggests that the event may have been caused by an asteroid that passed within Earth's Roche limit and broke up into a ring system, material from which then deorbited and formed the craters. It is also speculated that the shading of Earth by this ring may have contributed to the Hirnantian glaciation.^[10]

Possible craters

class=notpageimage|

Locations of possible craters related to the event

References

^ ^a ^b ^c Korochantseva, Ekaterina; Trieloff, Mario; Lorenz, Cyrill; Buykin, Alexey; Ivanova, Marina; Schwarz, Winfried; Hopp, Jens; Jessberger, Elmar (2007). "L-chondrite asteroid breakup tied to Ordovician meteorite shower by multiple isochron 40 Ar- 39 Ar dating". Meteoritics & Planetary Science. 42 (1): 113–130. Bibcode:2007M&PS...42..113K. doi:10.1111/j.1945-5100.2007.tb00221.x.
^ ^a ^b Lindskog, A.; Costa, M. M.; Rasmussen, C.M.Ø.; Connelly, J. N.; Eriksson, M. E. (2017-01-24). "Refined Ordovician timescale reveals no link between asteroid breakup and biodiversification". Nature Communications. 8: 14066. Bibcode:2017NatCo...814066L. doi:10.1038/ncomms14066. ISSN 2041-1723. PMC 5286199. PMID 28117834. It has been suggested that the Middle Ordovician meteorite bombardment played a crucial role in the Great Ordovician Biodiversification Event, but this study shows that the two phenomena were unrelated
^ H. Haack et al. Meteorite, asteroidal, and theoretical constraints on the 500-Ma disruption of the L chondrite parent body, Icarus, Vol. 119, p. 182 (1996).
^ Heck, Philipp; Birger Schmitz; Heinrich Baur; Alex N. Halliday; Rainer Wieler (15 July 2004). "Fast delivery of meteorites to Earth after a major asteroid collision". Nature. 430 (6997): 323–325. Bibcode:2004Natur.430..323H. doi:10.1038/nature02736. PMID 15254530. S2CID 4393398.
^ LINDSKOG, Anders; SCHMITZ, Birger; CRONHOLM, Anders; DRONOV, Andrei (2012-07-30). "A Russian record of a Middle Ordovician meteorite shower: Extraterrestrial chromite at Lynna River, St. Petersburg region". Meteoritics & Planetary Science. 47 (8): 1274–1290. Bibcode:2012M&PS...47.1274L. doi:10.1111/j.1945-5100.2012.01383.x. ISSN 1086-9379.
^ Cronholm, Anders; Schmitz, Birger (2010-07-01). "Extraterrestrial chromite distribution across the mid-Ordovician Puxi River section, central China: Evidence for a global major spike in flux of L-chondritic matter". Icarus. 208 (1): 36–48. Bibcode:2010Icar..208...36C. doi:10.1016/j.icarus.2010.02.004. ISSN 0019-1035.
^ Nature, Research Communities by Springer (2019-10-22). "Gigantic asteroid collision in the Ordovician period boosted biodiversity on Earth". Research Communities by Springer Nature. Retrieved 2024-05-16.
^ ^a ^b Schmitz, Birger; Harper, David; et al. (16 December 2007). "Asteroid breakup linked to the Great Ordovician Biodiversification Event" (PDF). Nature Geoscience. 1: 49–53. doi:10.1038/ngeo.2007.37. hdl:1912/2272. Archived from the original (PDF) on 22 September 2017.
^ An extraterrestrial trigger for the mid-Ordovician ice age: Dust from the breakup of the L-chondrite parent body, Birger Schmitz et al, AAAS Science Advances, 18 Sep 2019: Vol. 5, no. 9, eaax4184; DOI: 10.1126/sciadv.aax4184, accessed 2019-10-09
^ Tomkins, Andrew G.; Martin, Erin L.; Cawood, Peter A. (November 2024). "Evidence suggesting that earth had a ring in the Ordovician". Earth and Planetary Science Letters. 646: 118991. doi:10.1016/j.epsl.2024.118991.