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Letter. Late cretaceous seasonal ocean variability from the arctic

Letter. Late cretaceous seasonal ocean variability from the arctic
Letter. Late cretaceous seasonal ocean variability from the arctic
The modern Arctic Ocean is regarded as barometer of global change and amplifier of global warming1 and therefore records of past Arctic change are of a premium for palaeoclimate reconstruction. Little is known of the state of the Arctic Ocean in the greenhouse period of the late Cretaceous, yet records from such times may yield important clues to its future behaviour given current global warming trends. Here we present the first seasonally resolved sedimentary record from the Cretaceous from the Alpha Ridge of the Arctic Ocean. This “paleo-sediment trap” provides new insights into the workings of the Cretaceous marine biological carbon pump. Seasonal primary production was dominated by diatom algae but was not related to upwelling as previously hypothesised. Rather, production occurred within a stratified water column, involving specially adapted species in blooms resembling those of the modern North Pacific Subtropical Gyre, or those indicated for the Mediterranean sapropels. With increased CO2 levels and warming currently driving increased stratification in the global ocean, this style of production that is adapted to stratification may become more widespread. Our evidence for seasonal diatom production and flux testify to an ice-free summer, but thin accumulations of terrigenous sediment within the diatom ooze are consistent with the presence of intermittent sea ice in the winter, supporting a wide body of evidence for low temperatures in the Late Cretaceous Arctic Ocean, rather than recent suggestions of a 15 °C mean annual temperature at this time.
0028-0836
254-258
Davies, Andrew
dc4a10da-d700-4b73-aa81-2976d3b79576
Kemp, Alan E.S.
131b479e-c2c4-47ae-abe1-ad968490960e
Pike, Jennifer
e6ae12d6-3375-4bc3-9e86-547c9a217568
Davies, Andrew
dc4a10da-d700-4b73-aa81-2976d3b79576
Kemp, Alan E.S.
131b479e-c2c4-47ae-abe1-ad968490960e
Pike, Jennifer
e6ae12d6-3375-4bc3-9e86-547c9a217568

Davies, Andrew, Kemp, Alan E.S. and Pike, Jennifer (2009) Letter. Late cretaceous seasonal ocean variability from the arctic. Nature, 460, 254-258. (doi:10.1038/nature08141).

Record type: Article

Abstract

The modern Arctic Ocean is regarded as barometer of global change and amplifier of global warming1 and therefore records of past Arctic change are of a premium for palaeoclimate reconstruction. Little is known of the state of the Arctic Ocean in the greenhouse period of the late Cretaceous, yet records from such times may yield important clues to its future behaviour given current global warming trends. Here we present the first seasonally resolved sedimentary record from the Cretaceous from the Alpha Ridge of the Arctic Ocean. This “paleo-sediment trap” provides new insights into the workings of the Cretaceous marine biological carbon pump. Seasonal primary production was dominated by diatom algae but was not related to upwelling as previously hypothesised. Rather, production occurred within a stratified water column, involving specially adapted species in blooms resembling those of the modern North Pacific Subtropical Gyre, or those indicated for the Mediterranean sapropels. With increased CO2 levels and warming currently driving increased stratification in the global ocean, this style of production that is adapted to stratification may become more widespread. Our evidence for seasonal diatom production and flux testify to an ice-free summer, but thin accumulations of terrigenous sediment within the diatom ooze are consistent with the presence of intermittent sea ice in the winter, supporting a wide body of evidence for low temperatures in the Late Cretaceous Arctic Ocean, rather than recent suggestions of a 15 °C mean annual temperature at this time.

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Published date: 9 July 2009
Organisations: Ocean and Earth Science

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Local EPrints ID: 148555
URI: http://eprints.soton.ac.uk/id/eprint/148555
ISSN: 0028-0836
PURE UUID: 9b021a2a-2d0e-4a29-8ff5-0a0a9b431fa0

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Date deposited: 19 May 2010 10:48
Last modified: 14 Mar 2024 01:03

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Contributors

Author: Andrew Davies
Author: Alan E.S. Kemp
Author: Jennifer Pike

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