Stable isotope ratios and foraminiferal abundance of sediment cores from the Western Iberian Margin
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| Natura: | Dataset Open Access |
| Lingua: | en |
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PANGAEA
2003
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| _version_ | 1867169500516843520 |
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| author | Schönfeld, Joachim Zahn, Rainer de Abreu, Lucia |
| author_facet | Schönfeld, Joachim Zahn, Rainer de Abreu, Lucia |
| collection | Datos científicos de ciencias marinas y ambientales |
| contents | Rapid climate changes at the onset of the last deglaciation and during Heinrich Event H4 were studied in detail at IMAGES cores MD95-2039 and MD95-2040 from the Western Iberian margin. A major reorganisation of surface water hydrography, benthic foraminiferal community structure, and deepwater isotopic composition commenced already 540 years before the Last Isotopic Maximum (LIM) at 17.43 cal. ka and within 670 years affected all environments. Changes were initiated by meltwater spill in the Nordic Seas and northern North Atlantic that commenced 100 years before concomitant changes were felt off western Iberia. Benthic foraminiferal associations record the drawdown of deepwater oxygenation during meltwater and subsequent Heinrich Events H1 and H4 with a bloom of dysoxic species. At a water depth of 3380 m, benthic oxygen isotopes depict the influence of brines from sea ice formation during ice-rafting pulses and meltwater spill. The brines conceivably were a source of ventilation and provided oxygen to the deeper water masses. Some if not most of the lower deep water came from the South Atlantic. Benthic foraminiferal assemblages display a multi-centennial, approximately 300-year periodicity of oxygen supply at 2470-m water depth. This pattern suggests a probable influence of atmospheric oscillations on the thermohaline convection with frequencies similar to Holocene climate variations. For Heinrich Events H1 and H4, response times of surface water properties off western Iberia to meltwater injection to the Nordic Seas were extremely short, in the range of a few decades only. The ensuing reduction of deepwater ventilation commenced within 500-600 years after the first onset of meltwater spill. These fast temporal responses lend credence to numerical simulations that indicate ocean-climate responses on similar and even faster time scales. |
| format | Dataset Open Access |
| id | pangaea_https___doi_org_10_1594_PANGAEA_733303 |
| institution | PANGAEA |
| language | en |
| publishDate | 2003 |
| publisher | PANGAEA |
| record_format | pangaea |
| spellingShingle | Stable isotope ratios and foraminiferal abundance of sediment cores from the Western Iberian Margin Schönfeld, Joachim Zahn, Rainer de Abreu, Lucia CALYPSO; Calypso Corer; IMAGES; IMAGES I; International Marine Global Change Study; Marion Dufresne (1995); MD101__Campaign; MD952039; MD95-2039; MD952040; MD95-2040; Porto Seamount; Western Iberian Margin Rapid climate changes at the onset of the last deglaciation and during Heinrich Event H4 were studied in detail at IMAGES cores MD95-2039 and MD95-2040 from the Western Iberian margin. A major reorganisation of surface water hydrography, benthic foraminiferal community structure, and deepwater isotopic composition commenced already 540 years before the Last Isotopic Maximum (LIM) at 17.43 cal. ka and within 670 years affected all environments. Changes were initiated by meltwater spill in the Nordic Seas and northern North Atlantic that commenced 100 years before concomitant changes were felt off western Iberia. Benthic foraminiferal associations record the drawdown of deepwater oxygenation during meltwater and subsequent Heinrich Events H1 and H4 with a bloom of dysoxic species. At a water depth of 3380 m, benthic oxygen isotopes depict the influence of brines from sea ice formation during ice-rafting pulses and meltwater spill. The brines conceivably were a source of ventilation and provided oxygen to the deeper water masses. Some if not most of the lower deep water came from the South Atlantic. Benthic foraminiferal assemblages display a multi-centennial, approximately 300-year periodicity of oxygen supply at 2470-m water depth. This pattern suggests a probable influence of atmospheric oscillations on the thermohaline convection with frequencies similar to Holocene climate variations. For Heinrich Events H1 and H4, response times of surface water properties off western Iberia to meltwater injection to the Nordic Seas were extremely short, in the range of a few decades only. The ensuing reduction of deepwater ventilation commenced within 500-600 years after the first onset of meltwater spill. These fast temporal responses lend credence to numerical simulations that indicate ocean-climate responses on similar and even faster time scales. |
| title | Stable isotope ratios and foraminiferal abundance of sediment cores from the Western Iberian Margin |
| topic | CALYPSO; Calypso Corer; IMAGES; IMAGES I; International Marine Global Change Study; Marion Dufresne (1995); MD101__Campaign; MD952039; MD95-2039; MD952040; MD95-2040; Porto Seamount; Western Iberian Margin |
| url | https://doi.org/10.1594/PANGAEA.733303 |