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首页> 外文期刊>Paleoceanography >Age offsets among different biogenic and lithogenic components of sediment cores revealed by numerical modeling
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Age offsets among different biogenic and lithogenic components of sediment cores revealed by numerical modeling

机译：数值模拟揭示了沉积岩芯不同生源和成岩成分之间的年龄偏移

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摘要

For modeled sediment cores of the open ocean, a method for predicting simultaneously the ages of four different solid sediment compounds with respect to their depositional year onto the sediment surface is presented. The simulation of time-dependent age distribution in the sediment mixed layer and the eventually accumulating sediment is a prerequisite of a proper data assimilation of marine sediment core data into predictive climate models. Through such a data assimilation, marine paleoclimate data could then be efficiently used in order to optimally determine adjustable model parameters. The age simulation is based on a passive tracer transport method taking into account varying vertical advection rates within the sediment top layers, chemical pore water reactions, and bioturbation. It turns out that different weight fractions of the modeled sediment have different ages in one horizontal geometric depth-in-core level depending on the particle rain onto the sediment and the reactivity of the material within the sediment pore waters. For simultaneous consideration of paleoclimatic tracers associated within one and the same weight fraction, e.g., for calcium carbonate, tracers such as foraminiferal δ~(13)C, and calcium carbonate weight percentages, this may not be critical. However, for simultaneous consideration of calcium carbonate and opal weight percentages, the age difference in the observed weight fractions may have to be corrected. The age offset between CaCO_ 3 and opal depends criticaly on the sediment accumulation rate. Low-accumulation sites are more strongly affected than high-accumulation sites.
机译：对于开放海洋的模拟沉积物芯，提出了一种方法，可同时预测四种不同固体沉积物化合物相对于沉积物在沉积物表面上的沉积年限。模拟沉积物混合层中随时间变化的年龄分布以及最终积累的沉积物是将海洋沉积物核心数据正确地纳入预测性气候模型的前提。通过这种数据同化，可以有效地使用海洋古气候数据，以便最佳地确定可调整的模型参数。年龄模拟基于被动示踪剂传输方法，其中考虑了沉积物顶层内垂直对流速率的变化，化学孔隙水反应和生物扰动。结果表明，模拟的沉积物的不同重量分数在一个水平的几何核心深度水平上具有不同的年龄，具体取决于沉积物上的颗粒雨和沉积物孔隙水中物质的反应性。为了同时考虑在一个和相同重量分数内关联的古气候示踪剂（例如对于碳酸钙），示踪剂（例如有孔虫δ〜（13）C）和碳酸钙的重量百分比，这可能并不关键。但是，为了同时考虑碳酸钙和蛋白石的重量百分比，可能必须校正观察到的重量分数中的年龄差异。 CaCO_3和蛋白石之间的年龄偏移取决于沉积物的积累速率。低积累位点比高积累位点受到的影响更大。

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