The genesis of oceanic impact craters and impact-generated tsunami deposits
Goto, K. (2008). The genesis of oceanic impact craters and impact-generated tsunami deposits, in: Shiki, T. et al. (Ed.) Tsunamiites: features and implications. pp. 277-297
In: Shiki, T. et al. (2008). Tsunamiites: Features and implications. Elsevier: Amsterdam. ISBN 978-0-444-51552-0. xiii, 411 pp., more
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| Keywords |
Impacts
Water waves > Surface water waves > Tsunamis
Wave generation > Tsunami generation
Marine/Coastal |
| Author keywords |
Tsunami deposit, Tsunamiite, K-T boundary, Impact crater, Impact tsunami deposit, Impact tsunamiite |
| Abstract |
The properties of oceanic impact craters, the generation of impact tsunamis and the genesis of impact-generated tsunami deposits are reviewed based on studies of wellknown oceanic impacts. In the case of an oceanic impact, ocean water flows into the crater immediately after the impact. As a consequence, oceanic impact craters usually show little or no evidence at all of a high crater rim. The deposits formed by the inflowing water are concentrated in gullies eroded by the moving water mass as well as inside the crater. Impact-generated tsunami waves affect the surrounding ocean bottom and coastal areas, and tsunami deposits are formed around the crater. The Cretaceous/Tertiary (K/T)-boundary tsunami deposits are the best-studied impact-generated tsunami deposits. Their thickness decreases with distance from the Chicxulub crater. The K/T-boundary tsunami deposits have the following common properties: (1) similar thickness, grain-size and composition over a wide area; (2) opposite current directions in successive units or repeated compositional cycles that probably reflect recurrent tsunami currents; (3) the presence of terrestrial material such as plant and wood fragments and (4) the absence of a typical Bouma sequence. |
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