An astronomical perspective on Earth's geological record and evolution of life - What can 50 tonnes of rock and 100,000 litres of hydrochloric acid tell us?
Astronomy and astrophysics
Friday 03 October 2014
to 11:30 at
Birger Schmitz (Lund)
With the discovery that an asteroid impact caused the demise of the dinosaurs 65 Ma ago there has been a growing awareness that astronomical information can be gained also by looking down at Earth, rather than up at the sky. For twenty years we have pursued a systematic search for meteorites (1-21 cm in diameter) that fell on the sea floor in the Ordovician period 470 Ma ago. The search is pursued together with quarry workers that saw the lithified, ancient sea-floor sediments into floor plates. So far 100 meteorites have been found, representing almost all fossil meteorites known to science. The study gives the first insight into the meteorite flux to Earth at another time than the present. At 470 Ma ago one of the largest break-up events in the asteroid belt occurred, and this is reflected in the assemblage of fossil meteorites. Simultaneously with the asteroid breakup one of the most important events occurred in the history of life, the Great Ordovician Biodiversification Event, suggesting a possible relation. We have also developed an approach were relict meteoritic, very resistant spinel grains can be recovered from sedimentary rock of most ages in Earth's history. It will thus become possible to establish a detailed history of variations in the meteorite flux to Earth and to relate, with a very high resolution, geological events to astronomical events.