A stalagmite test of North Atlantic SST and Iberian hydroclimate linkages over the last two glacial cycles
A stalagmite test of North Atlantic SST and Iberian hydroclimate linkages over the last two glacial cycles
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DOI：
10.5194/cp-14-1893-2018
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发表时间：
2018-12-11
影响因子：
4.3
通讯作者：
Bicho, Nuno F.
中科院分区：
文献类型：
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作者：
Denniston, Rhawn F.;Houts, Amanda N.;Bicho, Nuno F.
伊比利亚水文气候和北大西洋海表温度（SST）在最近的冰期密切耦合已被确定通过分析海洋沉积物和花粉粒共同沉积在葡萄牙大陆边缘。虽然这些时间序列提供了精确的可验证记录，但缺乏跨越多个冰川循环的伊比利亚大陆气候的直接日期，特定地点的记录作为比较点。在这里，我们提出了一个高分辨率，多代理（增长动力学和三角洲C-13，三角洲O-18，和三角洲U-234值）复合石笋记录的水文气候从两个洞穴在葡萄牙西部的大部分最后两个冰期循环（类似于220万年）。在轨道和千年尺度上，基于石笋的水文气候代理与SST协变，三角洲C-13，三角洲O-18和三角洲U-234值升高和/或生长间断表明有效水分减少与主要冰筏碎片事件期间SST降低一致，与大陆气候的孢粉重建变化一致。虽然在许多情况下，葡萄牙石笋记录可以缩放到SST，在某些时间间隔的石笋同位素变化的幅度，并可能水文气候，似乎已经有点脱钩SST。
Close coupling of Iberian hydroclimate and North Atlantic sea surface temperature (SST) during recent glacial periods has been identified through the analysis of marine sediment and pollen grains co-deposited on the Portuguese continental margin. While offering precisely correlatable records, these time series have lacked a directly dated, site-specific record of continental Iberian climate spanning multiple glacial cycles as a point of comparison. Here we present a high-resolution, multi-proxy (growth dynamics and delta C-13, delta O-18, and delta U-234 values) composite stalagmite record of hydroclimate from two caves in western Portugal across the majority of the last two glacial cycles (similar to 220 ka). At orbital and millennial scales, stalagmite-based proxies for hydroclimate proxies covaried with SST, with elevated delta C-13, delta O-18, and delta U-234 values and/or growth hiatuses indicating re-duced effective moisture coincident with periods of lowered SST during major ice-rafted debris events, in agreement with changes in palynological reconstructions of continental climate. While in many cases the Portuguese stalagmite record can be scaled to SST, in some intervals the magnitudes of stalagmite isotopic shifts, and possibly hydroclimate, appear to have been somewhat decoupled from SST.