A late Miocene dust shower from the break-up of an asteroid in the main belt

Abstract

Throughout the history of the Solar System, Earth has been bombarded by interplanetary dust particles (IDPs), which are asteroid and comet fragments of diameter ~1–1,000 μm. The IDP flux is believed to be in quasi-steady state: particles created by episodic main belt collisions or cometary fragmentation replace those removed by comminution, dynamical ejection, and planetary or solar impact. Because IDPs are rich in ^(3)He, seafloor sediment ^(3)He concentrations provide a unique means of probing the major events that have affected the IDP flux and its source bodies over geological timescales. Here we report that collisional disruption of the >150-km-diameter asteroid that created the Veritas family 8.3 ± 0.5 Myr ago5 also produced a transient increase in the flux of interplanetary dust-derived ^(3)He. The increase began at 8.2 ± 0.1 Myr ago, reached a maximum of approx4 times pre-event levels, and dissipated over ~1.5 Myr. The terrestrial IDP accretion rate was overwhelmingly dominated by Veritas family fragments during the late Miocene. No other event of this magnitude over the past ~10^8 yr has been deduced from main belt asteroid orbits. One remarkably similar event is present in the ± record 35 Myr ago, but its origin by comet shower or asteroid collision remains uncertain.

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