Collaborative Research: Fabric and Seismic Anisotropy within the Lithospheric Mantle: Magnetic and Petrofabric Studies of Shear Zones in the New Caledonia Ophiolite

利用电子背散射衍射和高场各向异性磁化率技术相结合的方法，研究了新喀里多尼亚鱼绿岩天然剪切带地幔橄榄岩的结构发展和各向异性。电子背散射衍射提供了晶格优选取向的精确测量，并提供了滑移系统和变形温度的信息。高磁场各向异性磁化率是一种通过隔离硅酸盐的磁贡献来提供织物主轴方向和各向异性程度的新方法。磁化率法的高场各向异性比电子后向散射衍射要快得多，因此可以以更高的分辨率绘制变形梯度。该项目正在定量地确定高磁场各向异性与矿物织物各向异性之间的相关程度，这些各向异性是利用电子背散射衍射和其他成熟的方法，如通用阶段技术确定的。如果成功，新方法将允许更快速地研究大面积的地幔结构，从而有助于解释来自地幔的地震各向异性数据。

The development of fabric and anisotropy in mantle peridotites in natural shear zones of the New Caledonia ophiolite is being studied using a combination of electron backscatter diffraction and high-field anisotropy of magnetic susceptibility techniques to determine lattice preferred orientation. Electron backscatter diffraction provides an accurate measurement of lattice preferred orientation and yields information on slip systems and deformation temperatures. High-field anisotropy of magnetic susceptibility is a new method that provides the orientation of the fabric main axes and the degree of anisotropy by isolating the magnetic contribution of silicates. The high-field anisotropy of magnetic susceptibility method is considerably faster than electron backscatter diffraction and, therefore, allows mapping of deformation gradients at a higher resolution. The project is quantitatively establishing the degree of correlation between high-field magnetic anisotropy and mineral fabric anisotropy determined using electron backscatter diffraction and other well-established methods such as the universal stage technique. If successful, the new method will permit more rapid study of mantle fabrics over a large area, thus aiding interpretation of seismic anisotropy data from the mantle.