Initial test of the silicic acid leakage hypothesis using sedimentary biomarkers
Initial test of the silicic acid leakage hypothesis using sedimentary biomarkers
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DOI：
10.1029/2004gl020511
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发表时间：
2004-09
影响因子：
5.2
通讯作者：
M. Higginson;M. Altabet
中科院分区：
文献类型：
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作者：
M. Higginson;M. Altabet
已经提出了几种机制，在冰川终止，包括改变地表水营养供应的CaCO 3：Corg雨比，改变硅藻和颗石藻生产之间的平衡。硅藻Si：N在Fe胁迫的高纬度沃茨中最高。南大洋铁富集研究表明，硅藻对硅的需求在充满铁（冰川）的条件下减少，从而使增加的草酸在俯冲中层水中向北泄漏，并在低纬度地区上升。我们测试这个“硅酸渗漏”假说使用浮游植物特异性生物标志物的相对丰度在秘鲁边缘沉积物跨越0-20 Ka。结果表明，在18.0- 15.5Ka之间，球石藻：硅藻的产量从0.5增加到3。与初始pCO 2上升和早期冰消期模式水通气的变化的时间相关性暗示了亚南极模式水形成和铁丰度减少的巧合，可能是原因性重组。然而，球石藻生产随后下降，这表明雨比的变化只是部分负责的CO2冰消过渡。
Several mechanisms have been proposed for large CO2 changes at glacial Terminations, including shifting the CaCO3:Corg rain ratio by changing surface water nutrient supply, altering the balance between diatom and coccolithophore production. Diatom Si:N is highest in Fe‐stressed high‐latitude waters. Southern Ocean Fe enrichment studies suggest diatom Si demands reduced under Fe‐replete (glacial) conditions, allowing increased silicic acid to leak northward in subducted intermediate water and upwell at lower latitudes. We test this ‘Silicic Acid Leakage’ hypothesis using relative abundances of phytoplankton‐specific biomarkers in Peru margin sediments spanning 0–20 Ka. Results indicate increased coccolithophorid:diatom production from ∼0.5 to 3 between 18.0–15.5 Ka. Temporal correlation with the initial pCO2 rise and early deglacial shift in mode water ventilation implicates a coincidental, possibly causative reorganization of Sub‐Antarctic Mode Water formation and reduced Fe abundance. However, coccolithophorid production subsequently declined, suggesting rain ratio changes were only partly responsible for the CO2 deglacial transition.