Late Quaternary PCO2 Variations in the Angola Current: Evidence from Organic Carbon δ13C and Alkenone Temperatures
Late Quaternary PCO2 Variations in the Angola Current: Evidence from Organic Carbon δ13C and Alkenone Temperatures
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安哥拉海流中第四纪晚期 PCO2 变化：来自有机碳 δ13C 和烯酮温度的证据
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发表时间：
1994
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通讯作者：
G. Ruhland
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作者：
P. Müller;R. Schneider;G. Ruhland
安哥拉盆地东部晚第四纪沉积物中有机碳的δ 13 C记录显示出明显的旋回性，在第2 ~ 4期和第6期冰期δ 13 C值较高（-18.3 ~-20‰），而在第1 ~ 5期间冰期δ 13 C值较低（-20 ~-21.2‰）。根据kenone Uk 37指数得出的海面温度则相反，从冰期的20-22°C到间冰期的24-26°C不等。δ 13 Corg值与SST值之间的反比关系表明，同位素变化不是由于光合作用过程中依赖于温度的同位素分馏，在这种情况下，δ 13 Corg值将随着温度的升高而增加。沉积物δ 13 Corg与C/N比值之间的关系表明，不同比例的海洋和陆源有机质也可以排除作为δ 13 Corg变化的原因。相反，我们的结论是，地表水CO2浓度的变化是负责所观察到的冰期间冰期的同位素变化。
The δ13C record for organic carbon in Late Quaternary sediments of the Eastern Angola Basin shows a pronounced cyclicity with high values (-18.3 to -20‰) in glacial isotopic stages 2 to 4 and stage 6, and lower values (-20 to -21.2‰) in interglacial stages 1 and 5. Seasurface temperatures, derived from the alkenone Uk 37 index, vary in the opposite sense, ranging from 20–22°C in glacial stages up to 24–26°C in interglacial stages. The inverse relationship between δ13Corg and SST values suggests that the isotopic variations are not due to temperature-dependent isotopic fractionation during photosynthesis, in which case δ13Corg values would be expected to increase with increasing temperature. Relationships between sedimentary δ13Corg and C/N ratios indicate that differing proportions of marine and terrigenous organic matter can also be ruled out as a cause for the δ13Corg variability. Instead we conclude that changes in surface water CO2 concentrations were responsible for the observed glacial to interglacial isotopic variations.