June 2023
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204 Reads
Since the end of the last ice age, no cold snap rivals the one dated to 8200 years ago. Its oceanic response has been reconstructed in part from sediments in the Norwegian Sea and North Sea. Here we show that these sediments have been reworked by currents generated by the Storegga tsunami, dated to the coldest decades of the 8.2 ka event. From a new simulation of the Storegga tsunami we calculated the maximum flow velocity to be 2–5 m/s on the shelf offshore western Norway and in the shallower parts of the North Sea, and up to about 1 m/s down to a water depth of 1000 m. We re-investigated sediment core MD95-2011, from which a large and abrupt 8.2 ka cooling had been inferred, and found the cold-water foraminifera to be re-deposited and 11,000 years of age. Oxygen isotopes of the recycled foraminifera and the content of sand grains, thought to be dropped from ice bergs, might have led to an interpretation of a too large and dramatic climate cooling. Our simulations imply that large parts of the sea floor in the North Sea and Norwegian Sea might have been reworked by currents during the Storegga tsunami.