An Assessment of xsBa Flux as a Paleoproductivity Indicator and Its Water‐Depth Dependence in the Easternmost Equatorial Pacific Ocean
An Assessment of xsBa Flux as a Paleoproductivity Indicator and Its Water‐Depth Dependence in the Easternmost Equatorial Pacific Ocean
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赤道最东太平洋 xsBa 通量作为古生产力指标的评估及其水深依赖性
DOI：
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发表时间：
2020
影响因子：
3.5
通讯作者：
M. Lyle
中科院分区：
文献类型：
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作者：
Ajay K. Singh;F. Marcantonio;M. Lyle
我们首次在太平洋东赤道边缘巴拿马海盆记录了生物源钡(XsBa)通量的区域尺度，以评估xsBa作为古生产力指标的作用。对水深约700~3000m的13个岩心的xsBA测量表明，在海洋氧同位素第一阶段和第二阶段，230°归一化xsBA质量积累速率(MARS)随着水深的增加而增加。尽管总体沉积物MARS不同，沉积物再分配程度也不同，但XsBA MARS与深度之间存在很强的相关性。我们认为，xsBA随水深的增加可能是由于下落和/或重新悬浮的生物成因颗粒的持续分解和再矿化所致。在大多数岩心中，xsBa似乎不受成岩硫酸盐还原作用的影响。对沉淀物堆中xsba保留量的计算估计很高，在过去25个KYR期间一直在45%到52%之间波动。尽管xsBa通量可以作为古生产力的可靠指标，但如果(A)有证据表明正在分析的沉积物中硫酸盐还原，以及(B)有人试图量化位于水柱不同深度的不同地点之间的古生产力差异，则需要谨慎。
We present the first regional‐scale records of biogenic Barium (xsBa) fluxes in the Panama basin of the eastern‐equatorial margin of the Pacific Ocean in order to assess xsBa as a paleoproductivity proxy. Measurements of xsBa from 13 cores that range in water depths from about 700 to 3,000 m show an increase in 230Th‐normalized xsBa mass accumulation rates (MARs) with increasing water depth during both marine oxygen isotope stages (MIS) 1 and 2. The correlation of xsBa MARs with depth are strong despite differences in bulk sediment MARs and differing degrees of sediment redistribution. We interpret the increasing xsBa with water depth as likely due to the continued decomposition and remineralization of falling and/or resuspended biogenic particles. xsBa does not seem to be affected by diagenetic sulfate reduction in most of the cores. Calculated estimates of xsBa preservation in the sediment pile are high and fluctuate between 45% and 52% throughout the last 25 kyr. Although xsBa fluxes can be a robust indicator of paleoproductivity, caution is needed if (a) there is evidence of sulfate reduction in sediments being analyzed, and (b) one is trying to quantify differences in paleoproductivity among sites that are located at different depths in the water column.