岩矿石磁各向异性的理论计算与实验研究

THEORETICAL CALCULATION AND EXPERIMENTAL STUDY OF ROCK AND MINERAL SUSCEPTIBILITY ANISOTROPY

作者从铁磁学理论和磁化率张量概念出发,重点讨论形状与磁晶引起岩矿石磁各向异性的最主要原因,并以椭球体为例,导出了岩矿石磁各向异性的理论计算公式,结果表明岩矿石磁各向异性既受磁性颗粒各向异性的影响,也受矿物晶轴分布方式的影响。并由实验结果证明了强磁性矿物磁各向异常受形状影响大,而弱磁性矿物可不考虑形状影响。

There are two pridominant causes for the anisatropy of magnetic susceptibility of rocks and ferromagnetic minerals: The shape of the magnetic material and crystalline anisotropy. In general, these factors may seperate simultaneously, but in rock magnetism their effects are frequently separable. Thus based on ferromagnetism with susceptibility tensor, a theoretical formula is given: It is shown that the susceptibility anisotropy in rocks and minerals is effected hy the shape-effect anisotrapy of the ellipsoidal grain of the approximation, and also by the preferred orientation of the crystalline axes in uniaxial grains. The anisotrapy is chiefly due to the shape-effect in the high magnetite minerals, the anisotropy of the low magnetism grains of rocks or minerals effected by shape-effect is negligible. In the case of shape -effect anisotropy, based on the given formula, one can predict the degree of anisotropy, provided that the magnitude of the bulk susceptibility and the dimensions of the body are known. Using these relations or experiments, We can analyse and discuss the dominant origin or type of the mognetic anisotropy.