L-chondrite body breakup in Ordovician strata in China - A time tie point globally and across the inner solar system

Abstract

More than a quarter of all meteorites falling on Earth today originate from the breakup of the L-chondrite parent body (LCPB) ∼470 Ma ago, the largest documented asteroid breakup in the past ∼3 Ga. The event had a profound impact on the inner Solar System, resulting in an orders-of-magnitude increase in L-chondritic material in mid-Ordovician sediments on Earth. Here we show based on Ordovician strata at Puxi River, China, and Hällekis, Sweden, that the first arrival of LCPB dust to Earth can be used for global high-resolution correlation. The approach unravels a remarkable parallelism in facies development between distant paleocontinents and environmental perturbations on a global scale, possibly related to cooling of Earth by LCPB dust. In the Puxi River section, the first L-chondritic dust coincides with volcanic ash zircons, allowing U-Pb dating of the LCPB breakup. Ages determined from both sedimentary ash and recent L chondrites are consistently close to 470 Ma. A more precise age assessment is method-dependent, but the dual and independent dating options allow unique calibration possibilities. A similar increase in LCPB-derived dust as in Earth's sediments may exist in coeval layered deposits on Mars, the Moon, and large asteroids and may be used as a chronostratigraphic tie point on an astronomical scale.