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We have performed calculations of impacts into unconsolidated sediments beneath a shallow sea in order to better understand sediment transport in oceanic and continental shelf impacts. We apply these specifically to the Mjølnir impact crater in the central Barents Sea. The 40-km-diameter Mjølnir crater is one of the best preserved impact craters on Earth and one of the few where an ejecta layer-source crater correlation has been established. Extensive geophysical and geological data at Mjølnir unequivocally substantiate a meteorite bolide impact at ∼142 Ma into a sedimentary platform with 300-500 m paleo-water depth, and have revealed evidence of considerable immediately-after-impact sediment transport and erosion. The violence of an impact into water, including explosive vaporization, renders unconsolidated sediments nearly strengthless, and two-fluid instabilities facilitate the transport of large quantities of sediments over great distances. The simulations presented here have been conducted with the Los Alamos/SAIC adaptive grid hydrocode Sage.
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