Pressure and temperature dependence of shock remanence intensity for single-domain titanomagnetite-bearing basalt: Toward understanding the magnetic anomalies produced by impact events

Knowledge of shock remanent magnetization (SRM) property is crucial for interpreting the spatial change in a magnetic anomaly observed over an impact crater. This study conducted two series of impact-induced SRM acquisition experiments by varying the applied field and impact conditions, and the remanences of cube-shaped subsamples cut from shocked basalt containing single-domain titanomagnetite were measured to investigate the pressure and temperature dependence of the SRM intensity. The peak pressure and peak temperature distributions in the shocked samples were estimated using shock-physics modeling. SRM intensity was proportional to the apple field intensity up to 400 µT. The SRM intensities under different projectile conditions were consistent at the same pressure values. An empirical equation of SRM intensity is proposed to be the power function of pressure and a linear function of temperature, which can express the experimental SRM intensity values in a range of pressures up to 10 GPa and temperatures up to the Curie temperature. The magnetic anomaly estimation over an impact crater was demonstrated using the empirical equation, and the anomaly distribution shows a distinct feature approximated as a combination of two dipoles located at the basement of the crater and a deeper part.