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Carl Alwmark

Carl Alwmark

Senior lecturer

Carl Alwmark

Impact origin for the Hummeln structure (Sweden) and its link to the Ordovician disruption of the L chondrite parent body

Author

  • Carl Alwmark
  • L. Ferriere
  • Sanna Alwmark
  • J. Ormoe
  • H. Leroux
  • E. Sturkell

Summary, in English

Several studies of meteorites show that a large disruption of an asteroid occurred ca. 470 Ma in our solar system's asteroid belt. As a consequence, a large number of meteorite impacts occurred on Earth during the following few million years. The finding and characterization, for the first time, of planar deformation features in quartz grains from rocks collected at the Middle Ordovician Hummeln structure (Sweden) prove the hypervelocity impact origin of the structure. The unambiguous shock features allow us to close an similar to 200-yr-old discussion about its origin, and further the hypothesis of enhanced asteroid bombardment during the Middle Ordovician, adding an impact crater to the increasing number confirmed and properly dated from this period. Despite its relatively small size (similar to 1.2 km in diameter), similar to the young Meteor Crater (Arizona, USA), and its old age, the Hummeln structure is remarkably well preserved, contradicting the general assumption that small craters are not preserved on Earth for more than a few tens of thousands to a couple of million years.

Department/s

  • Lithosphere and Biosphere Science

Publishing year

2015

Language

English

Pages

279-282

Publication/Series

Geology

Volume

43

Issue

4

Document type

Journal article

Publisher

Geological Society of America

Topic

  • Geology

Status

Published

ISBN/ISSN/Other

  • ISSN: 0091-7613