Middle Miocene climate cooling linked to intensification of eastern equatorial Pacific upwelling
Middle Miocene climate cooling linked to intensification of eastern equatorial Pacific upwelling
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DOI：
10.1130/g34890.1
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发表时间：
2014-01-01
期刊：
影响因子：
5.8
通讯作者：
Andersen, Nils
中科院分区：
文献类型：
--
作者：
Holbourn, Ann;Kuhnt, Wolfgang;Andersen, Nils
在中中新世期间，随着南极洲永久性冰盖的重建，地球气候从相对温暖的阶段（中新世气候最适期）转变为较冷的模式，从而标志着新生代冷却的基本步骤。碳封存和通过提高陆地和/或海洋生产力来减少大气中二氧化碳含量已被认为是这一根本转变的主要驱动力。我们将高分辨率（1-3 k.y.）底栖稳定同位素数据与 X 射线荧光扫描仪得出的生物二氧化硅和碳酸盐累积估计值整合到保存得非常完好的沉积档案中（在综合海洋钻探计划站点 U1338 中恢复），以重建赤道东太平洋生产力变化并研究 16-13 Ma 期间高纬度和低纬度气候变化之间的时间联系。我们的记录显示，气候最适期（16.8-14.7 Ma）的特点是气候变化幅度大，其特点是碳循环的强烈扰动。 （南半球）日照最大值处的峰值温暖事件与碳酸盐补偿深度的短暂浅化和深海碳酸盐溶解的增强同时发生。 14.7Ma之后，气候变化转向倾斜速度，同时碳酸盐保存普遍改善，全球逐步变冷，最终导致南极洲上空大范围的冰生长。 13.8马。我们发现蛋白石积累量有两次大幅增加。 14.0 和大约。 13.8 Ma 发生在最后也是最显着的冷却步骤之前和期间，支持了赤道东太平洋硅质生产力增强有助于二氧化碳减少的假设。
During the Middle Miocene, Earth's climate transitioned from a relatively warm phase (Miocene climatic optimum) to a colder mode with reestablishment of permanent ice sheets on Antarctica, thus marking a fundamental step in Cenozoic cooling. Carbon sequestration and atmospheric CO2 drawdown through increased terrestrial and/or marine productivity have been proposed as the main drivers of this fundamental transition. We integrate high-resolution (1-3 k.y.) benthic stable isotope data with X-ray fluorescence scanner-derived biogenic silica and carbonate accumulation estimates in an exceptionally well preserved sedimentary archive, recovered at Integrated Ocean Drilling Program Site U1338, to reconstruct eastern equatorial Pacific productivity variations and to investigate temporal links between high- and low-latitude climate change over the interval 16-13 Ma. Our records show that the climatic optimum (16.8-14.7 Ma) was characterized by high-amplitude climate variations, marked by intense perturbations of the carbon cycle. Episodes of peak warmth at (Southern Hemisphere) insolation maxima coincided with transient shoaling of the carbonate compensation depth and enhanced carbonate dissolution in the deep ocean. A switch to obliquity-paced climate variability after 14.7 Ma concurred with a general improvement in carbonate preservation and the onset of step-wise global cooling, culminating with extensive ice growth over Antarctica ca. 13.8 Ma. We find that two massive increases in opal accumulation ca. 14.0 and ca. 13.8 Ma occurred just before and during the final and most prominent cooling step, supporting the hypothesis that enhanced siliceous productivity in the eastern equatorial Pacific contributed to CO2 drawdown.