The Massalia asteroid family as the origin of ordinary L chondrites

TL;DR

This study links the Massalia asteroid family to the origin of the most common meteorites on Earth, L chondrites, through spectroscopic and dynamical evidence, explaining their abundance and recent impact history.

Contribution

It provides the first comprehensive spectroscopic and dynamical analysis identifying the Massalia family as the source of L chondrites and Earth's impactors.

Findings

Massalia family is the primary source of L chondrites.

Massalia's location matches the distribution of L-chondrite-like NEOs.

Massalia's orbit explains the prevalence of L chondrites in meteorite falls.

Abstract

Studies of micrometeorites in mid-Ordovician limestones and Earth's impact craters indicate that our planet witnessed a massive infall of ordinary L chondrite material 466 million years (My) ago (Heck et al. 2017, Schmieder & Kring 2020, Kenkmann 2021) that may have been at the origin of the first major mass extinction event (Schmitz et al. 2019). The breakup of a large asteroid in the main belt is the likely cause of this massive infall. In modern times, material originating from this breakup still dominates meteorite falls (>20% of all falls) (Swindle et al. 2014). Here, we provide spectroscopic observations and dynamical evidence that the Massalia collisional family is the only plausible source of this catastrophic event and of the most abundant class of meteorites falling on Earth today. It is suitably located in the inner belt, at low-inclination orbits, which corresponds to the observed distribution of L-chondrite-like near-Earth objects (NEOs) and of interplanetary dust concentrated at 1.4 degrees (Sykes 1990, Reach et al. 1997).