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