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Meteorite flux to Earth in the Early Cretaceous as reconstructed from sediment-dispersed extraterrestrial spinels

Schmitz, Birger LU ; Heck, Philipp R.; Alvarez, Walter; Kita, Noriko T.; Rout, Surya S.; Cronholm, Anders LU ; Defouilloy, Céline; Martin, Ellinor LU ; Smit, Jan and Terfelt, Fredrik LU (2017) In Geology 45(9). p.807-810
Abstract
We show that Earth’s sedimentary strata can provide a record of the collisional evolution of the asteroid belt. From 1652 kg of pelagic Maiolica limestone of Berriasian–Hauterivian age from Italy, we recovered 108 extraterrestrial spinel grains (32–250 μm) representing relict minerals from coarse micrometeorites. Elemental and three oxygen isotope analyses were used to characterize the grains, providing a first-order estimate of the major types of asteroids delivering material at the time. Comparisons were made with meteorite-flux time “windows” in the Ordovician before and after the L-chondrite parent-body breakup. In the Early Cretaceous, ∼80% of the extraterrestrial spinels originated from ordinary chondrites. The ratios between the... (More)
We show that Earth’s sedimentary strata can provide a record of the collisional evolution of the asteroid belt. From 1652 kg of pelagic Maiolica limestone of Berriasian–Hauterivian age from Italy, we recovered 108 extraterrestrial spinel grains (32–250 μm) representing relict minerals from coarse micrometeorites. Elemental and three oxygen isotope analyses were used to characterize the grains, providing a first-order estimate of the major types of asteroids delivering material at the time. Comparisons were made with meteorite-flux time “windows” in the Ordovician before and after the L-chondrite parent-body breakup. In the Early Cretaceous, ∼80% of the extraterrestrial spinels originated from ordinary chondrites. The ratios between the three groups of ordinary chondrites, H, L, LL, appear similar to the present, ∼1:1:0.2, but differ significantly from Ordovician ratios. We found no signs of a hypothesized Baptistina LL-chondrite breakup event. About 10% of the grains in the Maiolica originate from achondritic meteorite types that are very rare (<1%) on Earth today, but that were even more common in the Ordovician. Because most meteorite groups have lower spinel content than the ordinary chondrites, our data indicate that the latter did not dominate the flux during the Early Cretaceous to the same extent as today. Based on studies of three windows in deep time, we argue that there may have been a gradual long-term (a few hundred million years) turnover in the meteorite flux from dominance of achondrites in the early Phanerozoic to ordinary chondrites in the late Phanerozoic, interrupted by short-term (a few million years) meteorite cascades from single asteroid breakup events. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Geology
volume
45
issue
9
pages
4 pages
publisher
Geological Society of America
external identifiers
  • scopus:85028501011
  • wos:000408588700012
ISSN
0091-7613
DOI
10.1130/G39297.1
language
English
LU publication?
yes
id
ca0cd1ac-480c-4c78-92c8-5e3b4c4ae4b8
date added to LUP
2017-09-11 09:46:32
date last changed
2018-01-16 13:25:28
@article{ca0cd1ac-480c-4c78-92c8-5e3b4c4ae4b8,
  abstract     = {We show that Earth’s sedimentary strata can provide a record of the collisional evolution of the asteroid belt. From 1652 kg of pelagic Maiolica limestone of Berriasian–Hauterivian age from Italy, we recovered 108 extraterrestrial spinel grains (32–250 μm) representing relict minerals from coarse micrometeorites. Elemental and three oxygen isotope analyses were used to characterize the grains, providing a first-order estimate of the major types of asteroids delivering material at the time. Comparisons were made with meteorite-flux time “windows” in the Ordovician before and after the L-chondrite parent-body breakup. In the Early Cretaceous, ∼80% of the extraterrestrial spinels originated from ordinary chondrites. The ratios between the three groups of ordinary chondrites, H, L, LL, appear similar to the present, ∼1:1:0.2, but differ significantly from Ordovician ratios. We found no signs of a hypothesized Baptistina LL-chondrite breakup event. About 10% of the grains in the Maiolica originate from achondritic meteorite types that are very rare (&lt;1%) on Earth today, but that were even more common in the Ordovician. Because most meteorite groups have lower spinel content than the ordinary chondrites, our data indicate that the latter did not dominate the flux during the Early Cretaceous to the same extent as today. Based on studies of three windows in deep time, we argue that there may have been a gradual long-term (a few hundred million years) turnover in the meteorite flux from dominance of achondrites in the early Phanerozoic to ordinary chondrites in the late Phanerozoic, interrupted by short-term (a few million years) meteorite cascades from single asteroid breakup events.},
  author       = {Schmitz, Birger and Heck, Philipp R. and Alvarez, Walter and Kita, Noriko T. and Rout, Surya S. and Cronholm, Anders and Defouilloy, Céline and Martin, Ellinor and Smit, Jan and Terfelt, Fredrik},
  issn         = {0091-7613},
  language     = {eng},
  number       = {9},
  pages        = {807--810},
  publisher    = {Geological Society of America},
  series       = {Geology},
  title        = {Meteorite flux to Earth in the Early Cretaceous as reconstructed from sediment-dispersed extraterrestrial spinels},
  url          = {http://dx.doi.org/10.1130/G39297.1},
  volume       = {45},
  year         = {2017},
}