Magnetic anisotropy of chloritoid

摘要: [1] The magnetocrystalline anisotropy of monoclinic chloritoid, a relatively common mineral in aluminum-rich, metapelitic rocks, has been determined for the first time by measuring high-field magnetic susceptibility (HF-AMS), using two independent approaches, i.e., (a) directional hysteresis measurements and (b) torque magnetometry, on collection single crystals collected from different tectonometamorphic settings worldwide. Magnetic remanence experiments show that all specimens contain ferromagnetic (s.l.) impurities, being mainly magnetite. The HF-AMS ellipsoids have highly oblate shape with minimum direction subparallel to crystallographic c-axis chloritoid. In basal plane though can be considered isotropic. degree is found 1.47, which significantly higher than most paramagnetic silicates even well above frequently used upper limit (i.e., 1.35) contribution AMS siliciclastic rocks. obtained values Curie temperature parallel (θ∥) perpendicular (θ⊥) indicate this pronounced related strong antiferromagnetic exchange interactions (θ⊥  0). As consequence, chloritoid-bearing metapelites alignment high without need invoking significant strongly anisotropic, minerals. newly discovered chloritoid thus calls revised approach fabric interpretations