Investigating the Accuracy, Precision, and Cooling Rate Dependence of Laboratory‐Acquired Thermal Remanences During Paleointensity Experiments
Investigating the Accuracy, Precision, and Cooling Rate Dependence of Laboratory‐Acquired Thermal Remanences During Paleointensity Experiments
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DOI：
10.1029/2018gc007946
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发表时间：
2019-01
期刊：
影响因子：
3.7
通讯作者：
C. N. Santos;L. Tauxe
中科院分区：
文献类型：
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作者：
C. N. Santos;L. Tauxe
我们在原始和实验室获得的热剩磁的古强度实验中检查了天然玄武岩和粗面岩样品的行为，并使用域状态代理来表征样品，包括帕特森（2011，https://doi.org/10.1029/2011JB008369）和帕特森等人的曲率（k）和体域稳定性参数。 （2017 年，https://doi.org/10.1073/pnas.1714047114）。使用 0.164 的曲率值（Paterson，2011 年建议，https://doi.org/10.1029/2011JB008369）作为将原始古强度数据上的单域类剩磁与多域类剩磁分开的关键阈值，用于将样本分为“直”（类单域）和“弯曲” （类似多域）组。两个样品组的样本在 70 μT 场中进行“新鲜”热剩磁，并进行内场零场、零场内场 (IZZI) 型（Yu 等人，2004 年，https://doi.org/10.1029/2003GC000630）古强度实验。直样本组以高精度恢复了实验室视野，而弯曲样本组则具有更加分散的结果（分别为 70.5 ± 1.5 和 71.9 ± 5.2 μT）。然而，直线和弯曲两组的平均强度非常接近 70 μT 的实验室视场，这表明如果实验包含足够数量的样本，则视场估计似乎不会存在较大偏差。我们发现，在大多数样品中，实验室热剩磁对冷却速率的依赖性很显着，并且不依赖于基于磁滞测量的代理推断出的磁畴状态，并且应对冷却速率与实验室使用的冷却速率不同的所有样品进行估计。
We examine the behavior of natural basaltic and trachytic samples during paleointensity experiments on both the original and laboratory‐acquired thermal remanences and characterize the samples using proxies for domain state including curvature (k) and the bulk domain stability parameters of Paterson (2011, https://doi.org/10.1029/2011JB008369) and Paterson et al. (2017, https://doi.org/10.1073/pnas.1714047114), respectively. A curvature value of 0.164 (suggested by Paterson, 2011, https://doi.org/10.1029/2011JB008369) as a critical threshold that separates single‐domain‐like remanences from multidomain‐like remanances on the original paleointensity data was used to separate samples into “straight” (single‐domain‐like) and “curved” (multidomain‐like) groups. Specimens from the two sample sets were given a “fresh” thermal remanent magnetization in a 70 μT field and subjected to an infield‐zerofield, zerofield‐infield (IZZI)‐type (Yu et al., 2004, https://doi.org/10.1029/2003GC000630) paleointensity experiment. The straight sample set recovered the laboratory field with high precision while the curved set had much more scattered results (70.5 ± 1.5 and 71.9 ± 5.2 μT, respectively). The average intensity of both sets for straight and curved was quite close to the laboratory field of 70 μT, however, suggesting that if experiments contain a sufficient number of specimens, there does not seem to be a large bias in the field estimate. We found that the dependence of the laboratory thermal remanent magnetization on cooling rate was significant in most samples and did not depend on domain states inferred from proxies based on hysteresis measurements and should be estimated for all samples whose cooling rates differ from that used in the laboratory.