Rapid transient changes in northeast Atlantic deep water ventilation age across Termination I
Rapid transient changes in northeast Atlantic deep water ventilation age across Termination I
复制标题
I 航站楼东北大西洋深水通气年龄的快速瞬态变化
DOI：
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
N. Shackleton
中科院分区：
文献类型：
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作者：
L. Skinner;N. Shackleton
[1]对东北大西洋深海岩芯(MD99-2334K；北纬37°48‘，西经10°10’；海拔3146米)的底栖和浮游有孔虫进行的加速器质谱仪(AMS)14C测年序列允许重建最后一次冰川消融的深水“14C通风年龄”。通过格陵兰冰芯和北大西洋浮游生物δ18Occ(方解石δ18O)记录的温度变化的同步，MD99-2334K的记录被放置在GISP2时间标尺上。根据对过去水源水Δ14C的一系列估计，可以估计14C预测通风年龄，以便与底栖-浮游14C年龄差异进行比较。尽管由于未知的深水Δ14C源信号和深水混合程度的不确定性，无法准确估计过去的通风年龄，但很明显，在最后一次冰川期间，东北大西洋的深水通风显著减少，随着博林-阿勒罗德变暖而突然增加，并在年轻的仙女木冷逆转期间再次迅速减少。这些变化的特征与北大西洋深水(NADW)与南极底层水(AABW)的不同优势相一致。平行的海底δ13C、深水温度(Tdw)和深水δ18O(δ180dw)估计支持这一推断。东北大西洋深水放射性碳含量的消冰期变化与大气放射性碳含量的相反变化平行，并与格陵兰温度波动平行，这一事实明确地暗示海洋环流在消冰期气候演变中的变化，并表明深海应对和促进气候突变的能力。
[1] A sequence of accelerator mass spectrometry (AMS) 14C dates performed on benthic and planktonic foraminifera from a northeast Atlantic deep-sea core (MD99-2334K; 37°48′N, 10°10′W; 3146 m) permit the reconstruction of deep water “14C ventilation ages” across the last deglaciation. The records from MD99-2334K have been placed on the GISP2 timescale via the synchrony of temperature changes recorded in the Greenland ice cores and in North Atlantic planktonic δ18Occ (calcite δ18O). On the basis of a range of estimates for past source water Δ14C, this permits the estimation of 14C projection ventilation ages for comparison with benthic-planktonic 14C age differences. Although the accurate estimation of past ventilation ages is precluded by unknown deep water Δ14C source signatures, and by uncertainty regarding the extent of deep water mixing, it is clear that deep water ventilation in the northeast Atlantic was significantly reduced during the last glaciation, increased abruptly coincident with the Bolling-Allerod warming, and rapidly became reduced again during the Younger Dryas cold reversal. The character of these changes is consistent with a varying dominance of North Atlantic Deep Water (NADW) versus Antarctic Bottom Water (AABW). Parallel benthic δ13C, deep water temperature (Tdw), and deep water δ18O (δ18Odw) estimates support this inference. The fact that deglacial changes in the deep water radiocarbon content of the northeast Atlantic run parallel to opposite changes in atmospheric radiocarbon content, and in parallel with Greenland temperature fluctuations, unequivocally implicates changes in ocean circulation in deglacial climate evolution and illustrates the capacity for the deep ocean to respond and contribute to abrupt climate change.