A Critical Appraisal of the “Day” Diagram
A Critical Appraisal of the “Day” Diagram
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DOI：
10.1002/2017jb015247
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发表时间：
2017-12
期刊：
影响因子：
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通讯作者：
A. Roberts;L. Tauxe;D. Heslop;Xiang Zhao;Zhaoxia Jiang
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文献类型：
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作者：
A. Roberts;L. Tauxe;D. Heslop;Xiang Zhao;Zhaoxia Jiang
“Day”图（Day等人，1977，https：//doi.org/10.1016/0031-9201（77）90108-X）被广泛用于推断磁性矿物组合的磁畴状态。基于理论和经验论证，将Day图划分为稳定的“单畴”（SD）、“伪单畴”（PSD）和“多畴”（MD）区。基于Day等人（1977，https：//doi.org/10.1016/0031-9201（77）90108-X）定义的边界，对样本进行必要的测量并在“域状态”框架内绘制结果是简单的。我们讨论了10个限制戴图解释的问题，包括（1）磁性矿物学，（2）相关的磁晶各向异性类型，（3）矿物化学计量，（4）应力状态，（5）表面氧化，（6）静磁相互作用，（7）颗粒形状，（8）热弛豫，（9）磁性颗粒混合物，（10）定义/测量问题。在大多数研究中，这些变量是未知的，无法控制，因此单个散装样品的滞后参数是不唯一的，日图中的任何数据点都可能由相关变量的无限组合产生。从这个关键的评价，我们认为，日图是从根本上模糊的域状态诊断。日线图的广泛使用也极大地促成了流行但有问题的观点，包括对地质记录中稳定SD颗粒的重要性认识不足，以及对无益的PSD概念及其地质重要性的强化。采用正确的磁畴状态诊断方法，对于磁性矿物组合的特定成分理解和定量岩石磁性解释来说，应该是一个紧迫的优先事项。
The “Day” diagram (Day et al., 1977, https://doi.org/10.1016/0031-9201(77)90108-X) is used widely to make inferences about the domain state of magnetic mineral assemblages. Based on theoretical and empirical arguments, the Day diagram is demarcated into stable “single domain” (SD), “pseudo single domain” (“PSD”), and “multidomain” (MD) zones. It is straightforward to make the necessary measurements for a sample and to plot results within the “domain state” framework based on the boundaries defined by Day et al. (1977, https://doi.org/10.1016/0031-9201(77)90108-X). We discuss 10 issues that limit Day diagram interpretation, including (1) magnetic mineralogy, (2) the associated magnetocrystalline anisotropy type, (3) mineral stoichiometry, (4) stress state, (5) surface oxidation, (6) magnetostatic interactions, (7) particle shape, (8) thermal relaxation, (9) magnetic particle mixtures, and (10) definitional/measurement issues. In most studies, these variables are unknowns and cannot be controlled for, so that hysteresis parameters for single bulk samples are nonunique and any data point in a Day diagram could result from infinite combinations of relevant variables. From this critical appraisal, we argue that the Day diagram is fundamentally ambiguous for domain state diagnosis. Widespread use of the Day diagram has also contributed significantly to prevalent but questionable views, including underrecognition of the importance of stable SD particles in the geological record and reinforcement of the unhelpful PSD concept and of its geological importance. Adoption of approaches that enable correct domain state diagnosis should be an urgent priority for component‐specific understanding of magnetic mineral assemblages and for quantitative rock magnetic interpretation.