Deep sea records from the southeast Labrador Sea: Ocean circulation changes and ice-rafting events during the last 160,000 years

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Deep sea records from the southeast Labrador Sea: Ocean circulation changes and ice-rafting events during the last 160,000 years. / Rasmussen, Tine; Oppo, DW; Thomsen, E; Lehman, SJ.

In: Paleoceanography, Vol. 18, No. 1, 2003.

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T1 - Deep sea records from the southeast Labrador Sea: Ocean circulation changes and ice-rafting events during the last 160,000 years

AU - Rasmussen, Tine

AU - Oppo, DW

AU - Thomsen, E

AU - Lehman, SJ

PY - 2003

Y1 - 2003

N2 - [1] Results from two deep sea cores from northeast of Newfoundland at 1251 and 2527 m water depth, respectively, indicate that during the time period from 160,000 to 10,000 years BP, ice rafting events in the Labrador Sea were accompanied by rapid variations in deep and surface water circulation. Twelve ice-rafting events occurred, each coinciding with high concentrations of detrital carbonate and oxygen isotopic depletion of both surface and bottom waters. Eleven of these can be correlated with the North Atlantic Heinrich events H1-H11. The remaining very conspicuous ice-rafting event took place early in MIS substage 5e, at a time when the planktic faunal assemblage suggests marked warming of the sea surface. In the shallower core, benthic delta(13)C values rise from a minimum during the deglaciation to peak substage 5e values following the last ice-rafting event, indicating that the ventilation of intermediate depths was renewed after the deglaciation was complete and continued throughout substage 5e. The benthic foraminifera suggest that this well-ventilated water mass was comparable to the modern Labrador Sea Water (LSW). The benthic faunas suggest that a relatively warm intermediate water mass entered the SE Labrador Sea during Heinrich events. Generally low benthic delta(13)C values indicate that this water mass was poorly ventilated and rich in inorganic nutrients. Isotope data and benthic faunal distributions indicate that North Atlantic Deep Water (NADW) formed in the Norwegian-Greenland Sea reached the SE Labrador Sea between the Heinrich events.

AB - [1] Results from two deep sea cores from northeast of Newfoundland at 1251 and 2527 m water depth, respectively, indicate that during the time period from 160,000 to 10,000 years BP, ice rafting events in the Labrador Sea were accompanied by rapid variations in deep and surface water circulation. Twelve ice-rafting events occurred, each coinciding with high concentrations of detrital carbonate and oxygen isotopic depletion of both surface and bottom waters. Eleven of these can be correlated with the North Atlantic Heinrich events H1-H11. The remaining very conspicuous ice-rafting event took place early in MIS substage 5e, at a time when the planktic faunal assemblage suggests marked warming of the sea surface. In the shallower core, benthic delta(13)C values rise from a minimum during the deglaciation to peak substage 5e values following the last ice-rafting event, indicating that the ventilation of intermediate depths was renewed after the deglaciation was complete and continued throughout substage 5e. The benthic foraminifera suggest that this well-ventilated water mass was comparable to the modern Labrador Sea Water (LSW). The benthic faunas suggest that a relatively warm intermediate water mass entered the SE Labrador Sea during Heinrich events. Generally low benthic delta(13)C values indicate that this water mass was poorly ventilated and rich in inorganic nutrients. Isotope data and benthic faunal distributions indicate that North Atlantic Deep Water (NADW) formed in the Norwegian-Greenland Sea reached the SE Labrador Sea between the Heinrich events.

KW - last climate

KW - cycle

KW - foraminifera

KW - ice rafting

KW - Paleoceanography

KW - Labrador Sea

U2 - 10.1029/2001PA000736

DO - 10.1029/2001PA000736

M3 - Article

VL - 18

JO - Paleoceanography

JF - Paleoceanography

SN - 0883-8305

IS - 1

ER -