The late Pliocene Benguela upwelling status revisited by means of multiple temperature proxies
The late Pliocene Benguela upwelling status revisited by means of multiple temperature proxies
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通过多个温度代理重新审视上新世晚期本格拉上升流状况
DOI：
10.1002/2013gc004940
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发表时间：
2014
期刊：
影响因子：
3.7
通讯作者：
Schneider
中科院分区：
文献类型：
--
作者：
Garbe-Schönberg;Regenberg;Contoux;Etourneau;Schneider
与晚更新世相比，本格拉地区基于烯酮的海表温度（SST）显示，在3.5至2.0 Ma之间记录到相对温暖和稳定的SST，并且与生物生产力增加的时期相吻合，如生物蛋白石沉积增加所揭示的。我们通过进行代理-代理比较，评估SST代理中记录的水文模式如何嵌入地质记录中。我们使用激光烧蚀电感耦合等离子体质谱法来测量浮游有孔虫物种Globigerina bulloides上的Mg/Ca，允许在单个有孔虫测试中原位测量Mg/Ca。Mg/Ca衍生的温度提供比烯酮衍生的SST低得多的温度，高达10°C。我们建立了一个情景，涉及对比的敏感性古温度计的年周期，即烯酮优先捕获SST时，表面海洋是温暖的平均年平均SST，和G。当上升流增强时，海表温度上升。多室分析也表明G. bulloidesmigrates海表面以下，而钙化的最后腔室之前配子，允许提取表面和次表面温度从Mg/Ca测量不同的腔室。我们的多个SST代理之间记录的温度范围是支持的温度范围与大气环流模型模拟时，不同的季节，不同的水深和不同的轨道配置发生在上新世晚期。上新世期间SST的一个更大的季节性周期可以解释烯酮和Mg/Ca衍生的温度对比，指出与今天相比，本格拉地区的上升流活动模式完全不同。
As compared to the late Pleistocene, Alkenone‐based sea surface temperature (SST) in the Benguela region revealed relatively warm and stable SST recorded between ∼3.5 and 2.0 Ma, and coincide with a period of increasing biological productivity as revealed by increasing deposition of biogenic opal. We assess how the hydrological patterns recorded in SST proxies are embedded in the geological record by performing a proxy‐proxy comparison. We used Laser‐Ablation Inductively Coupled Plasma‐Mass Spectrometry to measure the Mg/Ca on the planktonic foraminifera speciesGlobigerina bulloides, allowing in situ measurements of Mg/Ca on individual foraminiferal tests. Mg/Ca‐derived temperatures provide much colder temperatures than alkenone‐derived SST by up to 10°C. We build a scenario involving contrasting sensitivities of paleothermometers upon the annual cycle, namely alkenones preferentially capturing SST when the surface ocean is warmer than the mean‐annual average SST, andG. bulloidescapturing SST when upwelling intensifies. Multichamber analysis also suggests thatG. bulloidesmigrates below the sea surface while calcifying its last chambers prior to gametogenesis, allowing the extraction of both surface and subsurface temperature from Mg/Ca measured on different chambers. The range of temperatures recorded between our multiple SST proxies is supported by the range of temperatures simulated with a general circulation model when different seasons, different water depth and different orbital configurations occurring during the late Pliocene are considered. A greater seasonal cycle in SST during the Pliocene can account for alkenone and Mg/Ca‐derived temperature contrast, pointing to a radically different mode of upwelling activity in the Benguela region compared to today.
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影响因子：
3.7
作者：
G. Klinkhammer;A. Mix;B. Haley
通讯作者：
B. Haley
影响因子：
3.7
作者：
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K. Tachikawa;Sophie Sepulcre;T. Toyofuku;E. Bard
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影响因子：
5.3
作者：
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通讯作者：
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影响因子：
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作者：
L. Shannon
通讯作者：
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