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 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]
^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).
^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. ISSN1086-9379.
^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. ISSN0019-1035.