Assessing the ability of first-order reversal curve (FORC) diagrams to unravel complex magnetic signals
Assessing the ability of first-order reversal curve (FORC) diagrams to unravel complex magnetic signals
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DOI：
10.1029/2004jb003195
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发表时间：
2005-01-21
影响因子：
3.9
通讯作者：
Heslop, D
中科院分区：
文献类型：
--
作者：
Muxworthy, AR;King, JG;Heslop, D
[1]测量了不同磁相和双峰分布的混合物的一阶反转曲线（FORC）图，以检查FORC方法在解开复杂磁信号时的效率。各种磁性矿物，包括磁铁矿，磁赤铁矿，赤铁矿，针铁矿，和它们的线性加和的FORC分布进行了评估。仅含有硬磁性矿物如赤铁矿或针铁矿的混合物，其具有相对小的自发磁化（M-S）和大的磁晶各向异性，可以通过两个端元的线性相加来充分描述，因为相之间实际上没有静磁相互作用。以磁铁矿和磁赤铁矿等较软矿物为主的混合物更容易受到相互作用的影响，并表现出非线性行为。当具有低M-S的硬相（如赤铁矿）与具有高M-S的软相（如磁铁矿）混合时，仍然可以使用FORC技术进行识别，而使用标准磁滞测量则不可能这样做。当较弱的相可以被识别时，则弱-强混合物线性地增加;然而，超过某个临界浓度，具有高M-S的矿物淹没磁信号并且线性被破坏。结果表明，在磁铁矿等高磁化强度矿物存在的情况下，FORC法非常适合于识别少量的硬磁性矿物，如赤铁矿和针铁矿。
[1] First- order reversal curve ( FORC) diagrams for mixtures of different magnetic phases and bimodal distributions have been measured to examine the efficiency of the FORC method at unraveling complex magnetic signals. The FORC distributions for various magnetic minerals, including magnetite, maghemite, hematite, and goethite, and their linear additivity are assessed. Mixtures containing only hard magnetic minerals like hematite or goethite, which have relatively small spontaneous magnetizations ( M-S) and large magnetocrystalline anisotropies, can be adequately described by a linear addition of the two end- members, because there are virtually no magnetostatic interactions between the phases. Mixtures dominated by softer minerals like magnetite and maghemite are more susceptible to interactions and exhibit nonlinear behavior. When a hard phase with low M-S like hematite is mixed with a softer phase with high M-S like magnetite, it can still be identified using the FORC technique, whereas it is impossible to do so using standard magnetic hysteresis measurements. When the weaker phase can be identified, then weak-strong mixes add linearly; however, beyond a certain critical concentration the mineral with high M-S swamps the magnetic signal and linearity breaks down. It is suggested that the FORC method is highly suitable for identifying small traces of hard magnetic minerals like hematite and goethite in the presence of minerals with high M-S such as magnetite.