The meteorite flux of the last 2 Myr recorded in the Atacama desert

TL;DR

This study analyzes the terrestrial ages of meteorites in the Atacama Desert to understand the flux of meteorites to Earth over the last 2 million years, revealing flux intensity and compositional changes.

Contribution

It provides the oldest non-fossil meteorite collection data, estimating flux over 2 Myr and identifying compositional variability linked to asteroid belt dynamics.

Findings

Average meteorite flux: 222 meteorites >10 g per km2 per Myr

Detected increase in H chondrites between 0.5 and 1 Ma

Flux composition change suggests asteroid belt influence

Abstract

The evolution of the meteorite flux to the Earth can be studied by determining the terrestrial ages of meteorite collected in hot deserts. We have measured the terrestrial ages of 54 stony meteorites from the El M\'edano area, in the Atacama Desert, using the cosmogenic nuclide chlorine 36. With an average age of 710 ka, this collection is the oldest collection of non fossil meteorites at the Earth's surface. This allows both determining the average meteorite flux intensity over the last 2 Myr (222 meteorites larger than 10 g per km2 per Myr) and discussing its possible compositional variability over the Quaternary period. A change in the flux composition, with more abundant H chondrites, occurred between 0.5 and 1 Ma, possibly due to the direct delivery to Earth of a meteoroid swarm from the asteroid belt.