Introductory notes on shock remanent magnetization and shock demagnetization of igneous rocks

TLDR: In this article, the effects of mechanical shocks of about 0.5 msec in duration on the remanent magnetization of igneous rocks are experimentally studied, and the effect of applying a shock in the presence of a magnetic field (H), which is symbolically expressed asJ�Ω(H+S Ho) is proportional to the piezo-remanent magnetisation.

Abstract: Effects of mechanical shocks of about 0.5 msec in duration on the remanent magnetization of igneous rocks are experimentally studied. The remanent magnetization acquired by applying a shock (S) in the presence of a magnetic field (H), which is symbolically expressed asJ R (H+S Ho), is very large compared with the ordinary isothermal remanent magnetization (IRM) acquired in the same magnetic field.J R (H+S Ho) is proportional to the piezo-remanent magnetization,J R (H+P+Po Ho). The effect of applyingS in advance of an acquisition of IRM is represented symbolically byJ R (S H+ Ho).J R (S H+ Ho) can become much larger than the ordinary IRM, and is proportional to the advance effect of pressure on IRM,J R(P+ P0 H+ H0). The effect of shockS applied on IRM in non-magnetic space is represented by the shock-demagnetization effect,J R(H+ H0 S), which also is proportional toJ R(H+ H0 P+ P0). Because, the duration of a shock is very short, a single shock effect cannot achieve the final steady state. The effect ofn-time repeated shocks, is represented byJ 0+ΔJ *(n), whereJ 0 means the immediate effect and ΔJ *(n) represent the resultant effect of repeating, which is of mathematical expression proportional to [1−exp {−α(n−1)}].