The Effect of 30 to >100 GPa Shock on the Magnetic Properties of Chinga Iron Meteorite

We conducted a spherical shock-recovery experiment on the Chinga meteorite (Iron, ungrouped; ataxite). Explosively generated spherical shock wave traveled through the sample and created a range of pressures up to >100 GPa and temperatures, from ~250 °C at periphery up to >1000 °C in the center, along the radius of spherical sample. Shock wave propagation resulted in the formation of a central cavity and of three concentric zones of varying intensity of shock metamorphism and formation of shear bands, which were documented in iron meteorites for the first time as a result of artificial shock. The sample was then cut along the equatorial plane, and individual cubic specimens were extracted along the radius of the sphere and subjected to magnetic measurements. High and low-temperature magnetometry and thermomagnetic analyses revealed that the main magnetic carriers in Chinga ataxite are kamacite and tetrataenite. All specimens are magnetically soft and thus dominated by a typical multidomain behavior. The magnetic hardness of shocked samples (B_cr) varies within a dispersion range for unshocked samples; however, in the central zone, B_cr drops dramatically once the temperature of tetrataenite-to-taenite mineralogical transformation is reached. Hydrostatic pressure demagnetization experiments up to 1.8 GPa revealed that specimens from zone III (periphery, lower P–T) have much lower pressure sensitivity than specimens from zones I/II (more central, higher P–T). Pressure demagnetization degree is 6% for zone III and 57–74% for zones I/II. Investigation of natural remanent magnetization of the specimens revealed that the initial sample was most likely remagnetized after shock loading.