An extraterrestrial trigger for the mid-ordovician ice age: Dust from the breakup of the L-chondrite parent body

© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Schmitz, B., Farley, K. A., Goderis, S., Heck, P. R., Bergström, S. M., Boschi, S., Claeys, P., Debaille, V., Dronov, A., van Ginneken, M., Harper, D. A. T., Iqbal, F., Friberg, J., Liao, S., Martin, E., Meier, M. M. M., Peucker-Ehrenbrink, B., Soens, B., Wieler, R., & Terfelt, F. An extraterrestrial trigger for the mid-ordovician ice age: Dust from the breakup of the L-chondrite parent body. Science Advances, 5(9), (2019): eaax4184, doi:10.1126/sciadv.aax4184.The breakup of the L-chondrite parent body in the asteroid belt 466 million years (Ma) ago still delivers almost a third of all meteorites falling on Earth. Our new extraterrestrial chromite and 3He data for Ordovician sediments show that the breakup took place just at the onset of a major, eustatic sea level fall previously attributed to an Ordovician ice age. Shortly after the breakup, the flux to Earth of the most fine-grained, extraterrestrial material increased by three to four orders of magnitude. In the present stratosphere, extraterrestrial dust represents 1% of all the dust and has no climatic significance. Extraordinary amounts of dust in the entire inner solar system during >2 Ma following the L-chondrite breakup cooled Earth and triggered Ordovician icehouse conditions, sea level fall, and major faunal turnovers related to the Great Ordovician Biodiversification Event.B.Sc. was supported by the Swedish Research Council, the Knut and Alice Wallenberg Foundation, and an ERC-Advanced grant (ASTROGEOBIOSPHERE 213000). P.R.H. was supported by the Tawani Foundation. M.M.M.M. was supported by an Ambizione grant from the Swiss National Science Foundation. A.D. was supported by the Regional Governmental Program of Competitive Growth of Kazan Federal University and Russian Foundation for Basic Research (grant N19-05-00748). D.A.T.H. was supported by a fellowship from the Leverhulme Trust. S.G., P.C., M.v.G., and B.So. were supported by the Belgian Science Policy (Belspo), the FWO, and the VUB strategic program. V.D. was supported by the FRS-FNRS, Belspo, and the ERC-Starting Grant (ISoSyC 336718)