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Carl Alwmark

Carl Alwmark

Senior lecturer

Carl Alwmark

A global rain of micrometeorites following breakup of the L-chondrite parent body-Evidence from solar wind-implanted Ne in fossil extraterrestrial chromite grains from China

Author

  • Carl Alwmark
  • Birger Schmitz
  • Matthias Meier
  • H. Baur
  • R. Wieler

Summary, in English

Previous studies of limestone beds of mid-Ordovician age from both Sweden and China show that the Earth saw an at least two orders of magnitude increase in the influx of extraterrestrial material approximately 470 Ma, following the disruption of an L-chondrite parent body in the asteroid belt. Recovered extraterrestrial material consists of fossil meteorites and sediment-dispersed extraterrestrial chromite (SEC) grains, both with L-chondritic origin. Ne isotope analysis of SEC grains from one of the Swedish limestone sections revealed that the vast majority of the grains were delivered to Earth as micrometeorites. In this study, we extend the previous work, both in time and geographically, by measuring concentrations and isotopic ratios of Ne in individual SEC grains (60120 mu m in diameter) from three different beds from a contemporary Middle Ordovician limestone section in China. All of the Chinese SEC grains, 44 in total, contain surface-implanted Ne of fractionated solar wind composition, implying that these grains were, as in the case of the Swedish SEC grains, delivered to Earth as micrometeorites. This gives further compelling evidence that the two to three orders of magnitude increase in the influx of micrometeoritic material following the breakup of the L-chondrite parent body was indeed a global event. The rain of micrometeorites prevailed for at least 2 Myr (the estimated time of the deposition of the topmost Chinese bed) after the breakup event.

Department/s

  • Lithosphere and Biosphere Science
  • Nuclear physics

Publishing year

2012

Language

English

Pages

1297-1304

Publication/Series

Meteoritics and Planetary Science

Volume

47

Issue

8

Document type

Journal article

Publisher

Wiley-Blackwell

Topic

  • Subatomic Physics
  • Geology

Status

Published

ISBN/ISSN/Other

  • ISSN: 1086-9379