Comparison of magnetic hysteresis parameters of unremagnetized and remagnetized limestones
Comparison of magnetic hysteresis parameters of unremagnetized and remagnetized limestones
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未重磁化和重磁化石灰岩磁滞参数比较
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发表时间：
1994
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影响因子：
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通讯作者：
C. McCabe
中科院分区：
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作者：
J. Channell;C. McCabe
对于来自意大利的含白色磁铁矿的中生代远洋石灰岩（具有“初级”磁化），Mrs/Ms和Hcr/Hc值通常位于Day等人（1977）图的伪单畴（PSD）场中。Mrs/Ms对Hcr/Hc的对数图给出了一条直线（R = 0.814），其斜率和截距接近Parry（1982）关于单畴（SD）和多畴（MD）磁铁矿的经验混合线。对于其中一个白色远洋石灰岩地层（Maiolica地层），磁滞比接近MD场的样品显示出增加的顺磁磁化率，并且来自地层上部，其特征在于增加的碎屑粘土。因此，我们将增加MD磁铁矿与增加碎屑流入。对于粉红色和红色品种的意大利远洋石灰岩，赤铁矿的存在是明显的高饱和度领域，宽范围的Hcr/Hc，和“蜂腰”磁滞回线归因于磁铁矿和高结晶度自生赤铁矿的混合。从英国，内华达州，阿拉斯加州和阿巴拉契亚山脉的古生代和中生代重磁化含磁铁灰岩的集合的磁滞比主要位于PSD字段之外，似乎遵循幂律趋势。根据杰克逊等人（1993）的研究，高Hcr/Hc值和典型的“蜂腰”磁滞回线可以解释为细粒亚球形高磁导SD磁铁矿与高比例超顺磁性磁铁矿的混合。的斜率和截距的幂律关系的夫人/女士和Hcr/Hc的重磁化石灰岩是不同的意大利石灰岩观察到的，并可能提供一种手段的指纹磁铁矿的“初级”，而不是成岩起源。
For white magnetite-bearing Mesozoic pelagic limestones from Italy which carry a “primary” magnetization, the values of Mrs/Ms and Hcr/Hc generally lie in the pseudo-single domain (PSD) field of the Day et al. (1977) plot. The logarithmic plot of Mrs/Ms against Hcr/Hc gives a straight line (R = 0.814) with slope and intercept close to the empirical mixing line of Parry (1982) for single domain (SD) and multidomain (MD) magnetite. For one of the white pelagic limestone formations (Maiolica Formation), samples with hysteresis ratios closer to the MD field display increased paramagnetic susceptibility and are from the upper part of the formation characterized by increased detrital clay. We therefore associate the increased MD magnetite with increased detrital influx. For pinkish and reddish varieties of the Italian pelagic limestones, the presence of hematite is manifest by high saturation fields, a wide range of Hcr/Hc, and “wasp-waisted” hysteresis loops attributed to the mixing of magnetite and high-coercivity authigenic hematite. The hysteresis ratios for a collection of Paleozoic and Mesozoic remagnetized magnetite-bearing limestones from Britain, Nevada, Alaska and the Appalachians lie mainly outside the PSD field and appear to follow a power law trend. Following Jackson et al. (1993), the high values of Hcr/Hc and the characteristically “wasp-waisted” hysteresis loops can be interpreted in terms of a fine-grained subspherical high-coercivity SD magnetite mixed with a high proportion of superparamagnetic magnetite. The slope and intercept of the power law relationship for Mrs/Ms and Hcr/Hc in the remagnetized limestones are distinct from those observed for the Italian limestones, and may provide a means of fingerprinting magnetite of “primary” as opposed to diagenetic origin.