首页> 外文期刊>Journal of geophysical research. Solid earth: JGR >Influence of cooling rate on thermoremanence ofmagnetite grains: Identifying the role of different magnetic domain states
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Influence of cooling rate on thermoremanence ofmagnetite grains: Identifying the role of different magnetic domain states

机译:冷却速率对磁铁矿热剩磁的影响:确定不同磁畴状态的作用

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It is widely accepted that cooling rate can strongly influence the intensity of the thermal remanent magnetization (TRM) acquired by rocks during cooling to ambient temperatures. If ignored, this effect might lead to underestimates or overestimates of the ancient magnetic field intensity. To date, however, the cooling rate dependence of TRM acquired by particles with different domain states has never been systematically analyzed from the theoretical or experimental point of view. In this study, we present measurements of the TRM of synthetic magnetites with well-defined grain sizes that were quenched with constant cooling rates of 0.05, 0.1, 1, 3, 10, and 15 K/min. While single domain (SD) and small pseudo-single domain (PSD) samples are found to show larger TRMs after slow cooling, the TRMs of larger PSD and multidomain (MD) magnetites are not affected by an increase or decrease of the cooling rate. Overall, our results suggest that only smallest magnetite grains acquire a cooling rate-dependent TRM. Therefore, cooling rate corrections of paleointensity determinations are only necessary for samples dominated by SD remanence carriers, while rocks dominated by PSD and MD carriers, such as basalts, which are most commonly used for paleointensity studies, do not require such corrections.
机译:冷却速率会强烈影响岩石在冷却至环境温度期间获得的热剩余磁化强度(TRM)的强度,这一点已被广泛接受。如果忽略该影响,则可能导致对古代磁场强度的低估或高估。但是,迄今为止,从未从理论或实验的角度系统地分析过具有不同畴态的粒子所获得的TRM的冷却速率依赖性。在这项研究中,我们介绍了具有明确定义的晶粒尺寸的合成磁铁矿的TRM的测量值,这些磁铁矿以0.05、0.1、1、3、10和15 K / min的恒定冷却速率淬火。尽管发现单域(SD)和小的伪单域(PSD)样本在缓慢冷却后显示出较大的TRM,但是较大PSD和多域(MD)磁铁矿的TRM不受冷却速率增加或降低的影响。总体而言,我们的结果表明,只有最小的磁铁矿晶粒才能获得冷却速率相关的TRM。因此,对古强度测定的冷却速率校正仅对于以SD剩磁载体为主的样品是必需的,而以PSD和MD载体为主的岩石(如玄武岩)则是最常用于古强度研究的岩石,不需要进行校正。

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