【摘要】 本文通过将磁铁矿与赤铁矿进行人工混合,其中磁铁矿含量固定为0.3%,而赤铁矿含量则变化于0%~9%,并根据磁铁矿颗粒大小分为两个系列(纳米级磁铁矿+赤铁矿,系列1;假单畴磁铁矿+赤铁矿,系列2),探讨了磁性参数对上述磁性矿物混合比例的响应关系.结果显示:退磁参数S比值和Hcr/Hc不仅与磁铁矿和赤铁矿混合比例相关,同时也受到磁铁矿颗粒大小的影响,对于系列1而言,S比值对赤铁矿含量小于2%的混合样品较敏感,随着赤铁矿含量增加显著下降;Hcr/Hc则在赤铁矿含量大于3%时变化较大.通常用于指示亚铁磁性矿物颗粒大小的参数χARM/χ与χARM/SIRM,也受到磁铁矿与赤铁矿混合比例的影响,对于磁铁矿颗粒较细的系列1而言,当赤铁矿含量小于3%时,χARM/SIRM随着赤铁矿含量增加存在较为显著的下降现象.上述结果表明,当使用磁性参数进行环境解释时,需要同时考虑磁性矿物颗粒大小以及不同矫顽力矿物混合比例的影响,特别是磁铁矿以超顺磁颗粒为主的样品.更多还原

【Abstract】 In this study,magnetic measurements were conducted on two series of hematite and magnetite mixtures,with the purpose to study the response of magnetic parameters to the mixture of magnetic minerals with different coercivities.Series 1 and 2 were formed by mixing 0.3% superparamagnetic and pseudo-single-domain magnetite with varying proportions(0~9%) of hematite in a CaCO3 matrix,respectively.S ratios and Hcr/Hc,which are sensitive to the mixture of magnetic minerals with different coercivities,and are also impacted by the grain size of magnetite.S ratios of series 1 decline more dramatically than those of coarse-grained series 2 when the content of hematite is less than 2%.For series 1,Hcr/Hc ratios display larger variations when the hematite content is more than 3%.The results demonstrate that the widely used magnetic grain size indicators χARM/χ and χARM/ SIRM are also influenced by the proportions of ferrimagnetic versus antiferromagnetic minerals.For series 1 with fine-grained magnetite,χARM/SIRM shows an evident decline with increasing hematite content up to 3%.Meanwhile,this study indicates that there should be cautions in the interpretations of magnetic parameters.The influence of magnetite grain size on the coercivity indicators should be properly addressed,especially in the case of mixtwre composed of superparamagnetic magnetite and hematite.更多还原