Fundamental rock magnetic studies on single-domain particles, impressed magnetic anisotropy, and the application of rock magnetic techniques to petrophysics

本课程将研究岩石磁学的一些基础和应用方面。关于地球古代磁场（古地磁）的强度和方向的重要信息是由岩石中的稳定的小单畴（SD）粒子携带的。它们所携带的信息在岩石形成时就被锁定了，并且可以在数百万年的时间里保持稳定。这个项目将研究SD粒子的基本特性，并扩展我们最近的发现。特别是，我们最近证明了在SD粒子中存在一个磁矩可以存在的稳定位置范围。了解了这一重要特征，就有可能从各向异性岩石中改进古代磁场方向和强度的计算。这可能使得从比目前通常研究的更广泛的样本中获得有用的古地磁数据成为可能（包括更古老的样本，这些样本往往更具各向异性，并且由于难以从它们中估计可靠的古地磁数据而被忽视）。我们还将研究略大于SD大小的粒子的性质，并量化这些粒子转变为亚稳态SD状态的条件。这是非常重要的，因为它可能有助于解释为什么岩石中的自然剩余磁化（NRM）的很大一部分似乎存在于这些稍大的颗粒中。

This program will study some fundamental and applied aspects of rock magnetism. Important information concerning the intensity and direction of the Earth's ancient magnetic field (paleomagnetism) is carried by small stable single-domain (SD) particles in rocks. The information they carry is locked-in when the rock is formed, and can remain stable over millions of years. This program will study the fundamental properties of SD particles, and extend our recent discoveries. In particular, we have recently demonstrated that there is a range of stable positions in which the magnetic moment can lie in SD particles. Understanding this important feature potentially allows improved computations of the ancient field direction and intensity to be made from anisotropic rocks. This potentially allows useful paleomagnetic data to be obtained from a wider range of samples than are generally currently studied (including older samples, which are often more anisotropic and disregarded due to difficulties in estimating reliable paleomagnetic data from them). We will also be examining the properties of particles slightly larger than SD size, and quantifying the conditions under which these particles can transform into a metastable SD state. This is extremely important since it may help to explain why a significant fraction of the natural remanent magnetization (NRM) in rocks appears to reside in these slightly larger particles.