FLUX: Tracing the FLUX of cosmic dust arriving to Earth during the Phanerozoic

For the last 4.5 billion years, extraterrestrial (For the last 4.5 billion years, extraterrestrial (ET) materials have continuously bombarded the Earth. Today, the Solar System debris that reaches the Earth’s surface is dominated by particles less than 2 mm in size, termed micrometeorites (MMs). Until recently, the established misconception was that these MMs did not survive geological timescales, limiting reconstructions of the dust flux through time that are currently based on finding rare relict mineral phases or applying geochemical tools (e.g., Ir contents, 3He isotope ratios). Following a successful proof-of-concept study on a Late Devonian section, FLUX proposes first to extract fossil MMs from selected stratigraphic intervals across the Phanerozoic to document their characteristics and origin and second to use them as a novel high-resolution proxy to better understand the dynamical interactions between the Solar System and Earth. As such, fossil MMs may serve as an alternative new source of information on Solar System processes, complementary to classic meteorites. By combining expertise in meteoritics, geochemistry, and chemostratigraphy, FLUX addresses the following questions: 1) How did the flux of cosmic dust evolve during the Phanerozoic? 2) Can stratigraphic intervals marked by a dramatic increase in the mass of cosmic dust accreting to the Earth be identified? 3) Do increased ET flux events reflect asteroid family-forming events in the asteroid belt between Mars and Jupiter, and are they influenced by changes in the shape of Earth’s orbit? 4) Can oxidized iron-rich MMs be used to reconstruct the gross primary productivity or atmospheric CO2 levels of the deep past? 5) Did ET flux fluctuations affect the global Earth environment, for example through ocean fertilization? Ultimately, FLUX will better position the Earth in the context of a dynamic Solar System and constrain the causes and consequences of the variations in the flux of cosmic dust to Earth.