Persistently well-ventilated intermediate-depth ocean through the last deglaciation
Persistently well-ventilated intermediate-depth ocean through the last deglaciation
复制标题
DOI：
10.1038/s41561-020-0638-6
复制
发表时间：
2020-10-12
影响因子：
18.3
通讯作者：
Harpp, Karen S.
中科院分区：
文献类型：
--
作者：
Chen, Tianyu;Robinson, Laura F.;Harpp, Karen S.
在最后一次消冰期（类似于18- 11000年前），现有的中低纬度海洋中间水域的放射性碳（C-14）重建显示出广泛不同的趋势，其中一些大致跟踪大气，而另一些则表明极端消耗。这些差异模糊了我们对去冰川碳循环的理解，因为解释这些不同记录需要不同的假设，例如，注入的碳-14死地质碳，来自深海的极端孤立的水的混合，或者深水通风地点的变化。在这里，我们给出了加拉帕戈斯平台的中间水域的绝对年代的深海珊瑚C-14记录——接近报道的最大的去冰川C-14消耗——以及来自低纬度大西洋的数据。我们的记录表明，在整个消冰期，两大洋中相对于大气的中间水的C-14通气是连贯的，平衡良好的。在我们的记录中观测到的碳-14富集特征的总体趋势主要是由于在大气CO2增加的情况下，海气碳同位素交换效率增强。这些结果表明，来自有孔虫的C-14枯竭特征可能是沉积而不是水团特征，并为模拟末次冰期环流和碳循环的变化提供了严格的C-14约束。
During the last deglaciation (similar to 18-11 thousand years ago), existing radiocarbon (C-14) reconstructions of intermediate waters in the mid- to low-latitude oceans show widely diverging trends, with some broadly tracking the atmosphere and others suggesting extreme depletions. These discrepancies cloud our understanding of the deglacial carbon cycle because of the diversity of hypotheses needed to explain these diverging records, for example, injections of C-14-dead geological carbon, mixing of extremely isolated waters from the abyssal ocean or changes in sites of deep-water ventilation. Here we present absolutely dated deglacial deep-sea coral C-14 records of intermediate waters from the Galapagos Platform-close to the largest reported deglacial C-14 depletions-together with data from the low-latitude Atlantic. Our records indicate coherent, well-equilibrated intermediate-water C-14 ventilation in both oceans relative to the atmosphere throughout the deglaciation. The observed overall trend towards C-14-enriched signatures in our records is largely due to enhanced air-sea carbon isotope exchange efficiency under increasing atmosphericp CO2. These results suggest that the C-14-depleted signatures from foraminifera are likely sedimentary rather than water mass features, and provide tight C-14 constraints for modelling changes in circulation and carbon cycle during the last deglaciation.