Natalia S. Bezaeva

The effect of hydrostatic pressure up to 1.61 GPa on the Morin transition of hematite‐bearing rocks: Implications for planetary crustal magnetization

We present new experimental data on the dependence of the Morin transition temperature (TM) on hydrostatic pressure up to 1.61 GPa, obtained on a well-characterized multidomain hematite-bearing sample from a banded iron formation. We used a nonmagnetic high-pressure cell for pressure application and a Superconducting Quantum Interference Device magnetometer to measure the isothermal remanent magnetization (IRM) under pressure on warming from 243 K to room temperature (T0). IRM imparted at T0 under pressure in 270 mT magnetic field (IRM270mT) is not recovered after a cooling-warming cycle. Memory effect under pressure was quantified as IRM recovery decrease of 10%/GPa. TM, determined on warming, reaches T0 under hydrostatic pressure 1.38–1.61 GPa. The pressure dependence of TM up to 1.61 GPa is positive and essentially linear with a slope dTM/dP = (25 ± 2) K/GPa. This estimate is more precise than previous ones and allows quantifying the effect of a pressure wave on the upper crust magnetization, with special emphasis on Mars.

Magnetic properties of the Chelyabinsk meteorite: Preliminary results

This paper presents the distribution of magnetic susceptibility, χ0, in fragments of the Chelyabinsk ordinary chondrite (LL5, S4, W0, fall of February 15, 2013) from the collection of the Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, and results obtained by standard magnetic techniques for the meteorite material, including thermomagnetic analysis, measurements of natural remanent magnetization (NRM) and saturation isothermal remanent magnetization (SIRM), as well as the spectra of their alternating field demagnetization at amplitudes up to 170 mT, measurements of hysteresis loops and back-field remanence demagnetization curves at temperatures from 10 K to 700°C etc. The mean logχ0 values for the light-colored (main) lithology of the meteorite material and impact-melt breccia from our collection are 4.54 ± 0.10 (n = 66) and 4.65 ± 0.09 (n = 38) (×10−9 m3/kg), respectively. According to international magnetic classification of meteorites, Chelyabinsk falls within the range of LL5 chondrites. The mean metal content was estimated from the saturation magnetization, Ms, of the light- and dark-colored lithologies as 3.7 and 4.1 wt %, respectively. Hence, the dark lithology is richer in metal. The metal grains are multidomain at room temperature and show low coercive force, Bc (<2 mT) and remanent coercive force, Bcr (15–23 mT). The thermomagnetic analyses of the samples showed that the magnetic properties of the Chelyabinsk meteorite are controlled mainly by taenite and kamacite at temperatures >75 K. In the temperature range below 75 K, magnetic properties are controlled by chromite; the magnetic hardness of the samples is maximal at 10 K and equals to 606 and 157 mT for the light- and dark-colored lithologies, respectively.

Thermoremanence acquisition and demagnetization for titanomagnetite under lithospheric pressures

The geological sources of large-scale lithospheric magnetic field anomalies are poorly constrained. Understanding the magnetic behavior of rocks and minerals under the pressures and temperatures encountered at large crustal depths is particularly important in that task. The impact of lithospheric pressure is not well known and most of the time neglected in numerical models of the geological sources of magnetic anomalies. We present thermal remanent magnetization (TRM) acquisition, and stepwise thermal demagnetization on synthetic titanomagnetite dispersed powder, within an amagnetic cell under hydrostatic pressure up to 1 GPa. TRM is measured after thermal cycling within a cryogenic magnetometer. Pressure-dependent increase in the Curie temperature (initially in the 50-70 °C range) is observed, mostly between 0.3 and 0.6 GPa, on the order of 20 K/GPa. TRM intensity also increases with pressure up to 200% at 675 MPa, although the pressure variation with temperature inside the cell complicates the interpretation.

Behavior of basalt under laser-induced shock-wave application to the planetary hypervelocity impact effect

This paper presents the results of an investigation of the impact of laser-induced shock on basalt samples in a water confinement regime. In order to observe the effect of laser shock-wave propagation, in this material, the rear free surface velocity is measured by a velocimetry interferometer system for any reflector under various specified conditions. Parameters for an elastoplastic constitutive law and the Kanel’s damage model are provided and have been set up in such a way to ensure good correlation between numerical simulations and laboratory experiments. These resultant material properties, identified for the basalt sample studied here, could be used in future investigations looking to further correlating residual effects in material with pressure levels induced by water confined laser-matter interaction. This is of particular importance in meteoritics and planetary science due to the fact that hypervelocity impacts represent a major event taking place in the solar system, and shock waves generated ...

Effect of Hydrostatic Pressure on Isothermal Remanent Magnetization of Rocks

The effect of hydrostatic pressure (up to 1.3 GPa) on the isothermal remanent magnetization of rocks is studied experimentally using a new-type nonmagnetic high-pressure cell produced at the Institute of High-Pressure Physics (Troitsk, Moscow oblast). The experiments were carried out at the European Center for Research and Education in Environmental Geoscience (CEREGE), France.

Behaviour of basalt under shock-wave induced by laser: Application to planetary hypervelocity impact effect

This paper presents the study of basalt under shock induced by laser in water confinement regime. A model is developed to reproduce rear free surface velocity measured by Velocimetry interferometer for any reflector. Computation is in agreement with experiments. Material properties of basalt could be used for works aiming to correlate residual effects in material with pressure levels induced by water confined laser-matter interaction.This paper presents the study of basalt under shock induced by laser in water confinement regime. A model is developed to reproduce rear free surface velocity measured by Velocimetry interferometer for any reflector. Computation is in agreement with experiments. Material properties of basalt could be used for works aiming to correlate residual effects in material with pressure levels induced by water confined laser-matter interaction.