An astronomical perspective on Earth's geological .. (ASTROGEOBIOSPHERE)
An astronomical perspective on Earth's geological record and evolution of life
Date du début: 1 avr. 2012,
Date de fin: 31 mars 2017
"This project will develop the use of relict, extraterrestrial minerals in Archean to Cenozoic slowly formed sediments as tracers of events in the solar system and cosmos, and to decipher the possible relation between such events and evolution of life and environmental change on Earth. There has been consensus that it would not be possible to reconstruct variations in the flux of different types of meteorites to Earth through the ages. Meteorite falls are rare and meteorites weather and decay rapidly on the Earth surface. However, the last years we have developed the first realistic approach to circumvent these problems. Almost all meteorite types contain a small fraction of spinel minerals that survives weathering and can be recovered from large samples of condensed sediments of any age. Inside the spinels we can locate by synchrotron-light X-ray tomography 1-30 micron sized inclusions of most of the other minerals that made up the original meteorite. With cutting-edge frontier microanalyses such as Ne-21 (solar wind, galactic rays), oxygen isotopes (meteorite group and type) and cosmic ray tracks (supernova densities) we will be able to unravel from the geological record fundamental new information about the solar system at specific times through the past 3.8 Gyr. Variations in flux and types of meteorites may reflect solar-system and galaxy gravity disturbances as well as the sequence of disruptions of the parent bodies for meteorite types known and not yet known. Cosmic-ray tracks in spinels may identify the galactic year (230 Myr) in the geological record. For the first time it will be possible to systematically relate major global biotic and tectonic events, changes in sea-level, climate and asteroid and comet impacts to what happened in the larger astronomical realm. In essence, the project is a robust approach to establish a pioneer ""astrostratigraphy"" for Earth's geological record, complementing existing bio-, chemo-, and magnetostratigraphies."
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