Oligocene climate dynamics
Oligocene climate dynamics
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DOI：
10.1029/2004pa001042
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发表时间：
2004-12
期刊：
影响因子：
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通讯作者：
B. Wade;H. Pälike
中科院分区：
文献类型：
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作者：
B. Wade;H. Pälike
赤道太平洋渐新世（Ocean Drilling Program，Site 1218）的浮游和底栖有孔虫稳定同位素地层学是在磁年代C9 n和C11n.2n（~26.4-30 Ma，在新开发的天文校准时间尺度上）之间以6 kyr分辨率生成的。我们的数据允许详细检查渐新世古海洋学，早期冰冻圈的演变，以及轨道强迫对冰川海平面变化的影响。频谱分析揭示了能量和相干性的偏心率（40 kyr周期）和偏心率（~110，405 kyr）轨道带，偏心率和120万年的振幅周期，驱动冰盖振荡在南半球的一个额外的强大的印记。浮游有孔虫和底栖有孔虫？18 O被用来限制冰量和全球海平面变化的主要波动的幅度和时间。冰川事件，有关的结晶度和偏心率的变化，发生在29.16，27.91和26.76 Ma，对应的冰川海平面波动50-65米。高纬度温度和南极冰量的变化对全球碳埋藏和赤道生产力产生了重大影响，因为循环变化也记录在浮游和底栖有孔虫的碳同位素信号，水柱碳同位素梯度和散装沉积物的碳酸盐估计百分比中。我们还研究了渐新世期间氧和碳同位素事件与长期振幅包络极值之间的密切对应关系在天文计算中的意义，并在405 kyr离心率周期计数的基础上，发展了一种新的稳定同位素事件命名方案。
A planktonic and benthic foraminiferal stable isotope stratigraphy of the Oligocene equatorial Pacific (Ocean Drilling Program, Site 1218) was generated at 6 kyr resolution between magnetochrons C9n and C11n.2n (~26.4–30 Ma on a newly developed astronomically calibrated timescale). Our data allow a detailed examination of Oligocene paleoceanography, the evolution of the early cryosphere, and the influence of orbital forcing on glacioeustatic sea level variations. Spectral analysis reveals power and coherency for obliquity (40 kyr period) and eccentricity (~110, 405 kyr) orbital bands, with an additional strong imprint of the eccentricity and 1.2 Myr obliquity amplitude cycle, driving ice sheet oscillations in the Southern Hemisphere. Planktonic and benthic foraminifera ?18O are used to constrain the magnitude and timing of major fluctuations in ice volume and global sea level change. Glacial episodes, related to obliquity and eccentricity variations, occurred at 29.16, 27.91, and 26.76 Ma, corresponding to glacioeustatic sea level fluctuations of 50–65 m. Alteration of high-latitude temperatures and Antarctic ice volume had a significant impact on the global carbon burial and equatorial productivity, as cyclic variations are also recorded in the carbon isotope signal of planktonic and benthic foraminifera, the water column carbon isotope gradient, and estimated percent carbonate of bulk sediment. We also investigate the implications of a close correspondence between oxygen and carbon isotope events and long-term amplitude envelope extrema in astronomical calculations during the Oligocene, and develop a new naming scheme for stable isotope events, on the basis of the 405 kyr eccentricity cycle count.