An empirical scaling law for acquisition of thermoremanent magnetization

We describe a universal linear relationship between the acquisition magnetic field, B, and thermoremanent magnetization Mtr(Tr) measured at room temperature Tr. The efficiency ɛ(Tr) of a remanent magnetization (REM) is the ratio of the natural remanent magnetization Mnr(Tr) to the saturation remanence Jsr(Tr) . We report a power law relationship with exponent related to Js(Tr) and unit slope indicating a linear relationship. Thus logɛ(Tr) of Mtr(Tr) in equidimensional-shaped magnetic minerals of contrasting saturation magnetization Js(Tr) plots linearly with the logarithm of the applied magnetic field B along separate grain-size-independent straight lines with nearly unit slope and offsets related to Js(Tr). This empirical relationship is well suited for paleofield-intensity estimation, predicts strong magnetization of hematite and pyrrhotite in weak fields, and can be used as an assessment tool for observed remanence in planetary and meteoritic objects.