Fast delivery of meteorites to Earth after a major asteroid collision

Abstract

Very large collisions in the asteroid belt could lead temporarily to a substantial increase in the rate of impacts of meteorites on Earth. Orbital simulations predict that fragments from such events may arrive considerably faster than the typical transit times of meteorites falling today, because in some large impacts part of the debris is transferred directly into a resonant orbit with Jupiter. Such an efficient meteorite delivery track, however, has not been verified. Here we report high-sensitivity measurements of noble gases produced by cosmic rays in chromite grains from a unique suite of fossil meteorites preserved in approximately 480 million year old sediments. The transfer times deduced from the noble gases are as short as approximately 10(5) years, and they increase with stratigraphic height in agreement with the estimated duration of sedimentation. These data provide powerful evidence that this unusual meteorite occurrence was the result of a long-lasting rain of meteorites following the destruction of an asteroid, and show that at least one strong resonance in the main asteroid belt can deliver material into the inner Solar System within the short timescales suggested by dynamical models.

Asteroid breakup linked to the Great Ordovician Biodiversification Event

“…The results of the EC searches are shown in There is no indication that changes in sedimentation rates, on average a few millimeter per thousand years, can explain the observed major trend in EC concentrations, although individual beds may have formed at different rates. That the disruption event 5 occurred in the lower L. variabilis Zone is consistent with cosmic-ray induced 21 Ne ages of chromite grains from the fossil meteorites 13 Some of the best sections for studies of Ordovician invertebrate diversification occur in Baltoscandia 23 . We have established the mid-Ordovician biodiversity trends for brachiopods based on bed-by-bed sampling of more than 30,000 fossils from eight sections in Baltoscandia (Fig.…”

“…In the limestone beds containing common meteorites also abundant chromite grains from decomposed micrometeorites are found [10][11][12] . Cosmic-ray induced 21 Ne in chromite from the fossil meteorites increases upward in the strata, supporting a common origin from an asteroid breakup event 13 . High-precision 40 Ar- 39 Ar dating of recent L chondrites has constrained the timing of their parent-body disruption to 470 ±6 Ma, which is identical within uncertainties to the age of 467.3 ±1.6 Ma for the beds with fossil meteorites according to the latest geologic time scale 14 .…”

Noble gases in fossil micrometeorites and meteorites from 470 Myr old sediments from southern Sweden, and new evidence for the L‐chondrite parent body breakup event

“…Oxygen isotope data on chromites ) as well as petrographic evidence ) further support the L-chondrite classification of these fossil meteorites. Chromite proved to be retentive for cosmogenic (and in one case also for solar) noble gases (Heck et al 2003(Heck et al , 2004. Heck et al (2004) showed that the transfer times of the fossil L chondrites from their parent body to Earth, measured by cosmogenic noble gases, were unusually short compared to the transfer times of modern ordinary chondrites-only between 0.1-1 Myr.…”

“…Chromite proved to be retentive for cosmogenic (and in one case also for solar) noble gases (Heck et al 2003(Heck et al , 2004. Heck et al (2004) showed that the transfer times of the fossil L chondrites from their parent body to Earth, measured by cosmogenic noble gases, were unusually short compared to the transfer times of modern ordinary chondrites-only between 0.1-1 Myr. Furthermore, ages increase with decreasing sediment age (Heck et al 2004).…”

Determining the impactor of the Ordovician Lockne crater: Oxygen and neon isotopes in chromite versus sedimentary PGE signatures

“…For further details on the instrument, analytical procedures 127 and calculations, see Heck et al (2004Heck et al ( , 2008 and Meier et al (2010). 128…”