Southern Ocean upper water column structure over the last 140 kyr with emphasis on the glacial terminations

Mortyn, P, Charles CD, Hodell DA.  2002.  Southern Ocean upper water column structure over the last 140 kyr with emphasis on the glacial terminations. Global and Planetary Change. 34:241-252.

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atmospheric co2, carbon, deep, Foraminifera, glacial terminations, north-atlantic, oxygen isotopic composition, planktonic-foraminifera, productivity, reconstruction, sediments, Southern Ocean, temperature


We use delta(18)0 and delta(13)C isotopic records from both shallow- and deep-dwelling planktonic foraminiferal species to describe the transition of surface water column structure over the last two glacial terminations in the Atlantic sector of the Southern Ocean between 41degreesS-50degreesS. The delta(18)O differences between deep- and shallow-dwelling foraminifera are typically less pronounced before and during a termination than they are following a termination. Additionally, delta(13)C minima occur during terminations that may be linked to changes in thermohaline circulation mode. These observations collectively point toward water column structural changes that vary from relatively unstratified to relatively stratified during the course of a typical climate transition. The data can potentially be explained by southward retreats of surface water masses that previously advanced to the north during a typical glacial (i.e. frontal migration). Some of the delta(18)O phenomena can also be explained by subduction, entrainment, and advection of continental ice meltwater from higher latitudes. In either case, the glacial subantarctic between 41degreesS-50degreesS was less thermally stratified than it is today. (C) 2002 Elsevier Science B.V. All rights reserved.