Silicon cycling and opal production in the Atlantic: lessons from the last deglaciation

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• Kate Hendry, University of Bristol
• Thursday 13 October 2016, 17:30-18:30
• Latimer Room (Old Court), Clare College, Trinity Lane.

If you have a question about this talk, please contact Dr Rachael Rhodes.

Major shifts in ocean circulation are thought to be responsible for abrupt shifts in temperature and atmospheric CO2 as the Earth warmed up after the last ice age, linked to changes in latitudinal heat transport and deep ocean carbon storage. There is also widespread evidence for shifts in biological production during these times of deglacial CO2 rise, including enhanced growth of silica-producing algae (diatoms) in regions such as the equatorial Atlantic. In this talk, I’ll show how we can use marine sediment geochemical archives to demonstrate that the supply of dissolved silicon – a key nutrient for diatoms – was enhanced in the NE Atlantic during the abrupt climate events of the deglaciation. However, despite an enriched supply of this critical nutrient at depth, diatoms could only proliferate during abrupt climate shifts in regions of the NE Atlantic where the deep supply of dissolved silicon could reach the surface. These regions were influenced by enhanced regional wind-driven upwelling and weakened stratification due to circulation changes during phases of weakened Atlantic meridional overturning. Globally near-synchronous pulses of diatom production and enhanced subsurface concentrations of dissolved silicon suggest that widespread deglacial surface-driven breakdown of stratification, linked to changes in atmospheric circulation, had major consequences for biological productivity and carbon cycling across the North Atlantic.

This talk is part of the Quaternary Discussion Group (QDG) series.

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