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Ejecta from Ocean ImpactsNumerical simulations of deep-ocean impact provide some limits on the size of a projectile that will not mix with the ocean floor during a deep-ocean impact. For a vertical impact at asteroidal velocities (approx. 20 km/s), mixing is only likely when the projectile diameter is greater than 112 of the water depth. For oblique impacts, even larger projectiles will not mix with ocean floor silicates. Given the typical water depths of 4 to 5 km in deep-ocean basins, asteroidal projectiles with diameters as large as 2 or 3 km may commonly produce silicate ejecta that is composed only of meteoritic materials and seawater salts. However, the compressed water column beneath the projectile can still disrupt and shock metamorphose the ocean floor. Therefore, production of a separate, terrestrial ejecta component is not ruled out in the most extreme case. With increasing projectile size (or energy) relative to water depths, there must be a gradation between oceanic impacts and more conventional continental impacts. Given that 60% of the Earth's surface is covered by oceanic lithosphere and 500 m projectiles impact the Earth on 10(exp 5) y timescales, there must be hundreds of oceanic impact deposits in the sediment record awaiting discovery.
Document ID
20030064112
Document Type
Preprint (Draft being sent to journal)
Authors
Kyte, Frank T. (California Univ. Los Angeles, CA, United States)
Date Acquired
August 21, 2013
Publication Date
January 1, 2003
Subject Category
Lunar and Planetary Science and Exploration
Meeting Information
Conference on Submarine Craters and Ejecta-Crater Correlation(Svalbard)
Funding Number(s)
CONTRACT_GRANT: NAG5-9441
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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