The South Atlantic carbon isotope record of planktic foraminifera
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| Natura: | Dataset Open Access |
| Lingua: | en |
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PANGAEA
1999
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| _version_ | 1867170456419696640 |
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| author | Mulitza, Stefan Arz, Helge Wolfgang Kemle-von Mücke, Sylvia Moos, Christopher Niebler, Hans-Stefan Pätzold, Jürgen Segl, Monika |
| author_facet | Mulitza, Stefan Arz, Helge Wolfgang Kemle-von Mücke, Sylvia Moos, Christopher Niebler, Hans-Stefan Pätzold, Jürgen Segl, Monika |
| collection | Datos científicos de ciencias marinas y ambientales |
| contents | We reviewed the paleoceanographic application of the carbon isotope composition of planktic foraminifera. Major controls on the distribution of d13C of dissolved CO2 (d13CSCO2) in the modern ocean are photosynthesis-respiration cycle, isotopic fractionation during air-sea exchange, and circulation. The carbon isotope composition of surface waters is not recorded without perturbations by planktic foraminifera. Besides d13CSCO2 of the surrounding seawater, the d13C composition of planktic foraminifera is affected by vital effects, the water depth of calcification and postdepositional dissolution. We compared several high-resolution (>10cm/ka) carbon isotope records from the Southern Ocean, the Benguela upwelling system, and the tropical Atlantic. In the Southern Ocean, carbon isotope values are about 1.2 per mil lower during the LGM and up to 1.7 per mil lower during the last deglaciation, when compared to the Holocene. These depletions might be explained with a combination of a subsurface nutrient enrichment and reduced air-sea exchange due to an increased stratification of surface waters. In the Benguela Upwelling system, waters originating in the south are upwelled. While the deglacial minimum is transferred and recorded in its full extent in the d13C record of Globigerina bulloides, glacial values show only little changes. This might suggest, that the lower glacial d13C values of high-latitude surface waters are not upwelled off Namibia, or that G. bulloides records post-upwelling conditions, when increased seasonal production has already increased surface-water d13C. Synchronous to the d13C depletions in high latitudes, low d13C values were recorded in Globigerinoides sacculifer during the LGM and during the last deglaciation in the nutrient-depleted western equatorial Atlantic. Hence, part of the glacial-interglacial variability presumably transferred from high to low latitudes seems to be related to changes in thermodynamic fractionation. The variability in d13C is lowest in the northernmost core M35003-4 from the eastern Caribbean, implying that the Antarctic Intermediate Water might have acted as a conduit to transfer the deglacial minimum to tropical surface waters. |
| format | Dataset Open Access |
| id | pangaea_https___doi_org_10_1594_PANGAEA_728658 |
| institution | PANGAEA |
| language | en |
| publishDate | 1999 |
| publisher | PANGAEA |
| record_format | pangaea |
| spellingShingle | The South Atlantic carbon isotope record of planktic foraminifera Mulitza, Stefan Arz, Helge Wolfgang Kemle-von Mücke, Sylvia Moos, Christopher Niebler, Hans-Stefan Pätzold, Jürgen Segl, Monika Angola Basin; ANT-VIII/3; AWI_Paleo; GeoB; GeoB1023-5; GEOMAR; Geosciences, University of Bremen; Gravity corer (Kiel type); Helmholtz Centre for Ocean Research Kiel; M35/1; M35003-4; M6/6; Meteor (1986); Paleoenvironmental Reconstructions from Marine Sediments @ AWI; Polarstern; PS16; PS16/311; PS1768-8; SFB261; Shona Ridge; SL; South Atlantic in Late Quaternary: Reconstruction of Budget and Currents We reviewed the paleoceanographic application of the carbon isotope composition of planktic foraminifera. Major controls on the distribution of d13C of dissolved CO2 (d13CSCO2) in the modern ocean are photosynthesis-respiration cycle, isotopic fractionation during air-sea exchange, and circulation. The carbon isotope composition of surface waters is not recorded without perturbations by planktic foraminifera. Besides d13CSCO2 of the surrounding seawater, the d13C composition of planktic foraminifera is affected by vital effects, the water depth of calcification and postdepositional dissolution. We compared several high-resolution (>10cm/ka) carbon isotope records from the Southern Ocean, the Benguela upwelling system, and the tropical Atlantic. In the Southern Ocean, carbon isotope values are about 1.2 per mil lower during the LGM and up to 1.7 per mil lower during the last deglaciation, when compared to the Holocene. These depletions might be explained with a combination of a subsurface nutrient enrichment and reduced air-sea exchange due to an increased stratification of surface waters. In the Benguela Upwelling system, waters originating in the south are upwelled. While the deglacial minimum is transferred and recorded in its full extent in the d13C record of Globigerina bulloides, glacial values show only little changes. This might suggest, that the lower glacial d13C values of high-latitude surface waters are not upwelled off Namibia, or that G. bulloides records post-upwelling conditions, when increased seasonal production has already increased surface-water d13C. Synchronous to the d13C depletions in high latitudes, low d13C values were recorded in Globigerinoides sacculifer during the LGM and during the last deglaciation in the nutrient-depleted western equatorial Atlantic. Hence, part of the glacial-interglacial variability presumably transferred from high to low latitudes seems to be related to changes in thermodynamic fractionation. The variability in d13C is lowest in the northernmost core M35003-4 from the eastern Caribbean, implying that the Antarctic Intermediate Water might have acted as a conduit to transfer the deglacial minimum to tropical surface waters. |
| title | The South Atlantic carbon isotope record of planktic foraminifera |
| topic | Angola Basin; ANT-VIII/3; AWI_Paleo; GeoB; GeoB1023-5; GEOMAR; Geosciences, University of Bremen; Gravity corer (Kiel type); Helmholtz Centre for Ocean Research Kiel; M35/1; M35003-4; M6/6; Meteor (1986); Paleoenvironmental Reconstructions from Marine Sediments @ AWI; Polarstern; PS16; PS16/311; PS1768-8; SFB261; Shona Ridge; SL; South Atlantic in Late Quaternary: Reconstruction of Budget and Currents |
| url | https://doi.org/10.1594/PANGAEA.728658 |