Alkenone sea-surface temperatures and carbon burial at site 846 (Eastern Equatorial Pacific Ocean) : the last 1.3 M.Y.
Alkenone sea-surface temperatures and carbon burial at site 846 (Eastern Equatorial Pacific Ocean) : the last 1.3 M.Y.
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DOI：
10.2973/odp.proc.sr.138.131.1995
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
K. Emeis;H. Doose;A. Mix;D. Schulz-Bull
中科院分区：
文献类型：
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作者：
K. Emeis;H. Doose;A. Mix;D. Schulz-Bull
分析了赤道东太平洋846站沉积物中碳酸盐和有机碳的长链酮不饱和比（Uk）。根据海底以下0-46米复合深度剖面的同位素年龄模型和沉积物密度估计数，计算了这些生物化合物的积累率。我们结合温度和生物通量记录跟踪过去130万年南赤道电流起源的条件。ST在研究的时间间隔内波动很大。从1.3 Ma时的24°C开始逐渐下降的长期趋势在500至400 Ka之间结束，此时达到最低值19°C。自那时以来，温度数据表明，变暖的趋势，全新世调制高振幅的变化（19°至27°C）。在400和500 Ka之间的趋势反转与碳酸盐的最大聚集速率相一致，此后碳酸盐的聚集速率有所下降。相比之下，自那时以来，有机碳积累的变异性和绝对值都有所增加。在较短的时间尺度上，这些记录显示出与全球气候背景的密切联系。1.3Ma以来，碳酸盐（0.2- 3g/cm ~ 2 k.y.~ 1)有机碳积累速率（2-30 mg/cm ~ 2 k.y.~ 1)在底栖同位素记录的冰川盛期，当温度较低时，其含量一直很高（是现代值和间冰期值的两倍多）。然而，与δ 18 θ记录的交叉谱分析表明，有机碳通量的变化与SST的变化没有直接联系。我们记录中的最高温度导致间冰期事件发生了7千年。在100-k.y.偏心率周期和5 k. y.在41-k.y.循环周期。相比之下，有机碳积累的最大值落后于冰川最大值和低温14千年。在偏心周期中。在冰期/间冰期的时间尺度上，一个显着的影响，但不是对有机碳埋葬，在网站846似乎是平流的冷水进入南赤道电流。
We analyzed the unsaturation ratio (U k) of long-chain ketones—a molecular sea-surface temperature (SST) indicator—concentrations of carbonate and organic carbon in sediments from Site 846 in the eastern equatorial Pacific Ocean. Based on an isotopic age model for the composite depth section of 0-46 m below seafloor and on estimates of sediment density, accumulation rates of these biogenic compounds were calculated. Our combined temperature and biogenic flux record traces conditions at the origin of the South Equatorial Current over the last 1.3 m.y. S STs have fluctuated considerably over the interval studied. A long trend of gradual decrease from 24°C at 1.3 Ma ends between 500 and 400 Ka, when lowest values of 19°C were reached. Since this time, the temperature data indicate a warming trend to the Holocene modulated by high-amplitud e variation (19° to 27°C). The inversion of the trend between 400 and 500 Ka coincides with maximal accumulation rates of carbonate, which since then have decreased. In contrast, organic carbon accumulation since then has increased in variability and in absolute values. On shorter time scales, the records show a strong link to the global climatic background. Since 1.3 Ma, carbonate (0.2-3 g/cm2 k.y.~1) and organic carbon accumulation rates (2-30 mg/cm2 k.y.~1) were consistently high (more than twice their modern values and those of interglacials ) during glacial maxima in the benthic isotope record, when temperatures were low. However, cross-spectral analyses with the δ 18 θ record suggest that variation in organic carbon flux is not linked directly to variations in SST. Temperature maxima in our record led interglacial events by 7 k.y. in the 100-k.y. eccentricity cycle and by 5 k.y. in the 41-k.y. obliquity cycle. In contrast, maxima in organic carbon accumulation lag behind glacial maxima and low temperatures by 14 k.y. in the eccentricity cycle. On glacial/interglacial time scales, a prominent influence on SST—but not on organic carbon burial—at Site 846 appears to be the advection of cold water into the South Equatorial Current.