Reconstruction of the last deglaciation: deconvolved records of δ18O profiles, micropaleontological variations and accelerator mass spectrometric14C dating
Reconstruction of the last deglaciation: deconvolved records of δ18O profiles, micropaleontological variations and accelerator mass spectrometric14C dating
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最后一次冰消期的重建：δ18O剖面的去卷积记录、微古生物变化和加速器质谱14C测年
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发表时间：
1987
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通讯作者：
J. Duplessy
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作者：
E. Bard;M. Arnold;J. Duprat;J. Moyes;J. Duplessy
生物扰动在地层信号的位移和振幅降低中起着低通滤波器的作用。这常常导致地层记录中高频事件的丢失。此外，当考虑在地层“载体”（例如有孔虫）中测量的同位素信号δ 18 O、14 C时，生物扰动和载体丰度变化可能会产生伪影，这些伪影可能被错误地解释为古气候记录中的超前或滞后。我们提出了一个模型，其中生物扰动被视为时不变滤波器，其脉冲响应函数（IRF）类似于一阶系统的脉冲响应函数。该方法涉及首先去卷积载体的丰度曲线，然后使用恢复的“载体”丰度的同位素信号。这种分析最初用于人工生成理想曲线，目的是定性模拟生物扰动的影响。在此之后，使用来自岩心CH 73 - 139 C的数据，使用δ 18 O，A获得去卷积曲线。M. S. C ~（14）年龄和两种浮游有孔虫的丰度：G. bulloides和N.皮厚左卷曲。与未混合曲线的数据的比较，使分离的生物扰动文物和建设一个共同的冰川消退曲线的基础上恢复signals.Importantly，该模型强调了一些严重的限制，数学分析的地层信号。
Bioturbation acts as a low-pass filter in displacing and reducing the amplitudes of stratigraphic signals. This often leads to a loss of high-frequency events in the stratigraphic record. In addition, when considering an isotopic signal δ18O,14C measured in stratigraphic “carriers”, such as foraminifera, bioturbation and carrier abundance changes can create artifacts which may be falsely interpreted as leads or lags in the paleoclimatic record.We presenthere a model in which bioturbationis treated as a time-invariant filter whose impulse response function (IRF) is like that of a first-order system. The method involves first deconvoluting the abundance curves of the carriers and then the isotopic signals using the restored “carrier” abundances. This analysis was initially used to artificially generate ideal curves, with the aim of qualitatively modelling the effects of bioturbation. Following this, deconvolved curves were obtained using data from the core CH73-139C using δ18O, A. M. S. C-14 ages, and abundances of two planktonic foraminifera:G. bulloides andN. pachyderma left-coiling. A comparison of the data with the unmixed curves enables separation of the bioturbation artifacts and the construction of a common deglaciation curve based on the restored signals.Importantly, the model emphasizes some severe limitations of mathematical analysis of stratigraphic signals.