Linkages between rapid climate variability and deep-sea benthic foraminifera in the deep Subantarctic South Atlantic during the last 95 kyr
Linkages between rapid climate variability and deep-sea benthic foraminifera in the deep Subantarctic South Atlantic during the last 95 kyr
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DOI：
10.1002/2015pa002784
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发表时间：
2015-06
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通讯作者：
P. Diz;S. Barker
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作者：
P. Diz;S. Barker
我们提供了一个高分辨率的底栖有孔虫动物群的记录，从南开普省盆地(亚南极南大西洋)的沉积物岩芯中提取，横跨上一次冰川周期(95KYR)。由底栖有孔虫组合提供的信息，以及来自同一岩心的古气候指标，使我们能够解释初级生产方式(间歇性与持续性)与突然的气候振荡有关的变化。我们的结果表明，与植物碎屑相关的物种Eistominella exigua的丰度波动伴随着千年尺度的高纬度气候扰动。无论扰动的大小如何(即，海因里希事件与非海因里希事件)，在两极拉锯的负模式期间，浮游植物水华都会增加。我们提出了一个假设，将这些事件的频率和强度与大气扰动、半球间气候变异性和大气二氧化碳的千年尺度变化联系起来。总体模式的一个显著例外是，在全球同步开始的冰川海洋氧同位素阶段(MIS4)期间，甜菜的丰度普遍很高，根据非植物碎屑物种的百分比推断，这一阶段的特征通常是尘土增加和低质量的有机碳。这突出了亚南极地区管理信息系统4的特殊特点。
We present a high-resolution record of benthic foraminifera fauna from a sediment core retrieved from the South Cape Basin (Subantarctic South Atlantic) spanning the last glacial cycle (95 kyr). Information provided by benthic foraminiferal assemblages together with paleoclimate proxies from the same core allow us to interpret changes in the style of primary production (episodic versus sustained) in relation to abrupt climate oscillations. Our results indicate that fluctuations in the abundance of the phytodetritus-related species, Epistominella exigua, are concomitant with millennial-scale high-latitude climate perturbations. Episodic phytoplankton blooms increased during a negative mode of the bipolar seesaw, irrespective of the magnitude of the perturbation (i.e., Heinrich stadial versus non-Heinrich stadial events). We provide a hypothesis linking the frequency and intensity of these events to atmospheric perturbations, interhemispheric climate variability, and millennial-scale changes in atmospheric CO2. A notable exception to the overall pattern is the generally high abundance of E. exigua across the globally synchronous onset of glacial marine oxygen isotope stage (MIS) 4, a period generally characterized by increased dustiness and low-quality organic carbon as inferred by the percentage of the nonphytodetritus species. This highlights the special characteristics governing the onset of MIS 4 in the Subantarctic.