Remanence stability and magnetic fabric development in synthetic shear zones deformed at 500°C

摘要: Shear experiments were performed on magnetite-bearing calcite aggregates to examine magnetic fabric development and remanence stability in a deforming system using elevated temperature pressure encourage deformation by crystal-plastic processes. Samples composed of 1 wt % pseudo-single-domain magnetite (1–2 μm) matrix created with either strong or weak initial fabrics deformed coaxial simple shear strains up γ = 1.5 at constant strain rates between 6 × 10−5 10−4 s−1 500°C confining 300 MPa. given field thermal remanent magnetizations prior deformation. Demagnetization postdeformation reveals that primary magnetization can withstand pressures temperatures approximately equivalent greenschist facies metamorphic conditions laboratory time scales, but this is found depend the character predeformation fabric. The origin secondary components acquired during uncertain likely partially result from viscous remagnetization. Complete remagnetization initially anisotropic samples appears involve stress-softening piezoremanent mechanism. Postdeformation anisotropy measurements show progressive changes strength strain. In absence anisotropy, intensity increases linearly as function strain; however, overprinted an existing results apparent decrease low followed rapid increasing Our underscore important role play determining fabrics.