Stable isotope record of bentic foraminifera in sediment cores of the eastern Pacific ...

• Main Authors: Mix, Alan C, Pisias, Nicklas G, Zahn, Rainer, Rugh, W D, Lopez, Cody, Nelson, K
• Format: Article in Journal/Newspaper
• Language: English
• Published: PANGAEA 1991
• Subjects: Piston corer; RC13; V19; Robert Conrad; Vema; North Atlantic
• Online Access: https://dx.doi.org/10.1594/pangaea.701404; https://doi.pangaea.de/10.1594/PANGAEA.701404

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 ... : Supplement to: Mix, Alan C; Pisias, Nicklas G; Zahn, Rainer; Rugh, W D; Lopez, Cody; Nelson, K (1991): Carbon 13 in Pacific deep and intermediate waters, 0-370 ka: implications for ocean circulation and Pleistocene CO2. Paleoceanography, 6(2), 205-226 ...