Stable isotope record of bentic foraminifera in sediment cores of the eastern Pacific
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| Auteurs principaux: | , , , , , |
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| Format: | Dataset Open Access |
| Langue: | en |
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PANGAEA
1991
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| _version_ | 1867169497452904448 |
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| author | Mix, Alan C Pisias, Nicklas G Zahn, Rainer Rugh, W D Lopez, Cody Nelson, K |
| author_facet | Mix, Alan C Pisias, Nicklas G Zahn, Rainer Rugh, W D Lopez, Cody Nelson, K |
| collection | Datos científicos de ciencias marinas y ambientales |
| contents | Stable isotopes in benthic foraminifera from Pacific sediments are used to assess hypotheses of systematic shifts in the depth distribution of oceanic nutrients and carbon during the ice ages. The carbon isotope differences between ~1400 and ~3200 m depth in the eastern Pacific are consistently greater in glacial than interglacial maxima over the last ~370 kyr. This phenomenon of "bottom heavy" glacial nutrient distributions, which Boyle proposed as a cause of Pleistocene CO2 change, occurs primarily in the 1/100 and 1/41 kyr**-1 "Milankovitch" orbital frequency bands but appears to lack a coherent 1/23 kyr**-1 band related to orbital precession. Averaged over oxygen-isotope stages, glacial delta13C gradients from ~1400 to ~3200 m depth are 0.1 per mil greater than interglacial gradients. The range of extreme shifts is somewhat larger, 0.2 to 0.5 per mil . In both cases, these changes in Pacific delta13C distributions are much smaller than observed in shorter records from the North Atlantic. This may be too small to be a dominant cause of atmospheric pCO2 change, unless current models underestimate the sensitivity of pCO2 to nutrient redistributions. This dampening of Pacific relative to Atlantic delta13C depth gradient favors a North Atlantic origin of the phenomenon, although local variations of Pacific intermediate water masses can not be excluded at present. |
| format | Dataset Open Access |
| id | pangaea_https___doi_org_10_1594_PANGAEA_701404 |
| institution | PANGAEA |
| language | en |
| publishDate | 1991 |
| publisher | PANGAEA |
| record_format | pangaea |
| spellingShingle | Stable isotope record of bentic foraminifera in sediment cores of the eastern Pacific Mix, Alan C Pisias, Nicklas G Zahn, Rainer Rugh, W D Lopez, Cody Nelson, K PC; Piston corer; RC13; RC13-110; Robert Conrad; V19; V19-27; Vema Stable isotopes in benthic foraminifera from Pacific sediments are used to assess hypotheses of systematic shifts in the depth distribution of oceanic nutrients and carbon during the ice ages. The carbon isotope differences between ~1400 and ~3200 m depth in the eastern Pacific are consistently greater in glacial than interglacial maxima over the last ~370 kyr. This phenomenon of "bottom heavy" glacial nutrient distributions, which Boyle proposed as a cause of Pleistocene CO2 change, occurs primarily in the 1/100 and 1/41 kyr**-1 "Milankovitch" orbital frequency bands but appears to lack a coherent 1/23 kyr**-1 band related to orbital precession. Averaged over oxygen-isotope stages, glacial delta13C gradients from ~1400 to ~3200 m depth are 0.1 per mil greater than interglacial gradients. The range of extreme shifts is somewhat larger, 0.2 to 0.5 per mil . In both cases, these changes in Pacific delta13C distributions are much smaller than observed in shorter records from the North Atlantic. This may be too small to be a dominant cause of atmospheric pCO2 change, unless current models underestimate the sensitivity of pCO2 to nutrient redistributions. This dampening of Pacific relative to Atlantic delta13C depth gradient favors a North Atlantic origin of the phenomenon, although local variations of Pacific intermediate water masses can not be excluded at present. |
| title | Stable isotope record of bentic foraminifera in sediment cores of the eastern Pacific |
| topic | PC; Piston corer; RC13; RC13-110; Robert Conrad; V19; V19-27; Vema |
| url | https://doi.org/10.1594/PANGAEA.701404 |