Impact cratering record of Sweden-A review

Publikation: Bidrag til bog/antologi/rapportBidrag til bog/antologiForskningfagfællebedømt

  • Sanna Holm-Alwmark

Studies of impact structures in Sweden date back almost 60 years. They have so far resulted in the confirmation and understanding of eight impact structures and one impact-derived breccia layer, including the largest confirmed impact structure in the western part of Europe, the Siljan impact structure. Several additional structures have been proposed as impact derived, but they have to date not been confirmed. In this contribution, I summarize the current state of knowledge about the impact cratering record of Sweden. This is an up-to-date, comprehensive review of the features of known impact structures (and impact-related deposits) in Sweden. The described impact structures formed over a time period spanning from the Cambrian to the Cretaceous, and the preservation of several small (∼1-2 km in diameter) Paleozoic impact structures indicates that the conditions securing their protection were close to optimal, with formation in a shallow epicontinental sea and rapid cover by protective sediments followed by a regional geologic evolution permitting their preservation. The generally well-preserved state of some of these crater structures contradicts the general assumption that such small impact structures can only be preserved for approximately a couple of thousand to a few million years. The Lockne-Målingen, Tvären, Granby, and Hummeln impact structures all have ages that place their formation in a period of proposed increased cratering rate on Earth following the breakup event of the L-chondrite parent body in the asteroid belt. However, to date, evidence other than a temporal correlation is missing for all of these structures except for Lockne (and Målingen), which has been shown to have formed by the impact of an L-chondritic body.

OriginalsprogEngelsk
TitelLarge Meteorite Impacts and Planetary Evolution VI
RedaktørerWolf Uwe Reimold, Christian Koeberl
ForlagThe Geological Society of America
Publikationsdato2021
Sider1-39
Kapitel1
ISBN (Elektronisk)9780813795508
DOI
StatusUdgivet - 2021
NavnGeological Society of America. Special Papers
Vol/bind550
ISSN0072-1077

Bibliografisk note

Funding Information:
I would like to acknowledge Maurits Lindström for introducing the field of impact cratering with his fantastic guiding at Siljan and Lockne. Also, the Network NiR (Project leader H. Dypvik at Oslo University) provided great opportunities to visit Swedish (and other) impact structures, and to initiate new collaborations. A. Lindskog is thanked for fruitful discussions and help on aspects of paleontology and sedimentology. R.A.F. Grieve is thanked for providing constructive criticism on a previous version of this manuscript. Thanks go to K. Högdahl for discussing the Revsund granite and for advice on references. A. Deutsch is thanked for providing the reference to Mäerz (1979). Many thanks also go to J. Lindgren for support and guidance. M. Cal-ner, M. Eriksson, and C. Alwmark are thanked for their advice. Thanks also go to J. Ormö for kindly providing photographs and for commenting on a previous version of this manuscript. Constructive criticism from M. Poelchau, one anonymous reviewer, as well as the editor, W.U. Reimold, which improved the manuscript, is gratefully acknowledged. The author was financially supported by an international postdoctoral grant from the Swedish Research Council (grant no. 2017-06388).

Publisher Copyright:
© 2021 The Geological Society of America.

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