Fundamental rock magnetic studies on single-domain particles and anisotropy, and applications to paleomagnetism and petrophysics

本课程将研究岩石磁学的一些基本方面，及其在古地磁学和岩石物理学中的应用。关于地球、月球、岩石行星和陨石在地质历史中的古磁场（古地磁）的强度和方向的重要信息是由岩石中的小稳定单畴（SSD）磁性颗粒携带的。它们携带的磁性信息在岩石形成时被锁定（称为自然反射磁化，NRM），并且可以在数百万年内保持稳定。这些信息对于理解岩石行星体的磁历史至关重要，并为重建地球上过去的板块构造运动提供数据。本程序将研究SSD粒子的一些基本性质。其中一个主要目的是改进对各向异性岩石（岩石的性质在不同方向上变化）的古磁场方向和强度的计算，这将使有用的古地磁数据能够从比迄今为止可能的更广泛的样本中获得。这可能包括更古老的样本，这些样本通常更具各向异性，并且以前可能没有生成可靠的古地磁数据。这反过来又可能使板块构造重建能够在更早的时间进行。另一个关键方面将是研究略大于SSD尺寸的颗粒的性质，并量化这些颗粒可以转变为亚稳态单畴状态的条件。这很重要，因为它可能有助于解释为什么岩石中的NRM的显着部分似乎存在于这些稍大的颗粒中。 该计划还将研究被称为超顺磁性（SP）的较小单畴粒子的基本性质。虽然这些颗粒不保留剩磁，因此在古磁学方面并不重要，但我们正在开拓它们作为纳米颗粒造影剂的用途。它们的高磁化率和小尺寸使其成为监测水力压裂作业的进展和环境影响、监测油砂生产过程以及对加拿大经济重要的其他应用的理想示踪剂。 该计划的另一个目的是进一步建立岩石磁性和岩石物理参数之间的联系。特别是，我们的目标是量化磁各向异性和其他关键岩石物理性质（如流体渗透率各向异性，声学各向异性，电各向异性）的各向异性之间的关系。这可能会提供一种手段，估计这些其他岩石物理性质的快速，非破坏性的磁各向异性技术。这将具有重要的应用，用于优化页岩油和天然气区带的生产，以及各向异性是关键因素的其他类型的储层。

This program will study some fundamental aspects of rock magnetism, and its application to paleomagnetism and petrophysics. Important information concerning the intensity and direction of the ancient magnetic fields (paleomagnetism) of the Earth, Moon, rocky planets and meteorites in the geological past is carried by small stable single-domain (SSD) magnetic particles in rocks. The magnetic information they carry is locked-in when the rock is formed (called a natural remanent magnetization, NRM), and can remain stable over millions of years. This information is crucial for understanding the magnetic history of rocky planetary bodies, and for providing the data for reconstructing past plate tectonic motions on the Earth. This program will study some fundamental properties of SSD particles. One of the main aims is to improve computations of the ancient field direction and intensity from anisotropic rocks (rocks whose properties vary in different directions), which would enable useful paleomagnetic data to be obtained from a wider range of samples than has hitherto been possible. This could include older samples that are often more anisotropic and where reliable paleomagnetic data may not previously have been generated. This in turn could potentially allow plate tectonic reconstructions to be made further back in time. Another key aspect will be studying the properties of particles slightly larger than SSD size, and quantifying the conditions under which these particles can transform into metastable single-domain states. This is important since it may help to explain why a significant fraction of the NRM in rocks appears to reside in these slightly larger particles. The program will also study the fundamental properties of smaller single-domain particles that are termed superparamagnetic (SP). Whilst these particles do not retain a remanent magnetization, and are therefore not important in terms of paleomagnetism, we are pioneering their use as nanoparticle contrast agents. Their high magnetic susceptibility and small size makes them ideal tracers for monitoring the progress and environmental effects of hydraulic fracturing operations, monitoring production processes in the oil sands, and other applications important to the Canadian economy. Another aim of the program is to further establish links between rock magnetism and petrophysical parameters. In particular, we aim to quantify the relationships between magnetic anisotropy and the anisotropies of other key petrophysical properties (such as fluid permeability anisotropy, acoustic anisotropy, electrical anisotropy). This potentially will provide a means of estimating these other petrophysical properties from rapid, non-destructive magnetic anisotropy techniques. This would have important applications for optimizing production in shale oil and gas plays, and other types of reservoir where anisotropy is a key factor.