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本和应用方面。有关地球古代磁场(古地磁)强度和方向的重要信息由岩石中稳定的单域(SD)小颗粒携带。它们携带的信息在岩石形成时被锁定，并可以在数百万年内保持稳定。这个项目将研究SD粒子的基本性质，并扩展我们最近的发现。特别是，我们最近证明了在SD粒子中存在一个稳定的位置，磁矩可以位于这个位置范围内。了解这一重要特征可能有助于改进各向异性岩石对远古磁场方向和强度的计算。这可能使有用的古地磁数据能够从比目前普遍研究的样本范围更广的样本中获得(包括较老的样本，这些样本往往更加各向异性，由于难以估计可靠的古地磁数据而被忽视)。我们还将检查略大于SD尺寸的粒子的性质，并量化这些粒子可以转变为亚稳态SD状态的条件。这一点非常重要，因为它可能有助于解释为什么岩石中很大一部分自然剩余磁化(NRM)似乎存在于这些略大一些的颗粒中。

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.