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Sci Adv. 2019 Sep 18;5(9):eaax4184. doi: 10.1126/sciadv.aax4184. eCollection 2019 Sep.

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

Author information

1
Astrogeobiology Laboratory, Department of Physics, Lund University, Lund, Sweden.
2
Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA.
3
Department of Chemistry, Vrije Universiteit Brussel, Brussels, Belgium.
4
Robert A. Pritzker Center for Meteoritics and Polar Studies, The Field Museum of Natural History, Chicago, IL, USA.
5
Department of the Geophysical Sciences, The University of Chicago, Chicago, IL, USA.
6
School of Earth Sciences, The Ohio State University, Columbus, OH, USA.
7
Analytical, Environmental, and Geo-Chemistry, Vrije Universiteit Brussel, Brussels, Belgium.
8
Laboratoire G-Time, Université Libre de Bruxelles, Brussels, Belgium.
9
Geological Institute, Russian Academy of Sciences, Moscow, Russia.
10
Institute of Geology and Oil and Gas Technologies, Kazan (Volga Region) Federal University, Kazan, Russia.
11
Royal Belgian Institute of Natural Sciences, Brussels, Belgium.
12
Department of Earth Sciences, Durham University, Durham, UK.
13
Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing, China.
14
CAS Center for Excellence in Comparative Planetology, Hefei, China.
15
Department of Earth Sciences, ETH Zürich, Zürich, Switzerland.
16
Naturmuseum St. Gallen, St. Gallen, Switzerland.
17
Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA.

Abstract

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.

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