Numerical modeling of magnetization of a precipitating rock suspension

Abstract

The influence of collisions between the clusters of a precipitating material on its magnetization at the precipitation stage in an aqueous medium is analyzed. In laboratory experiments, when the sedimentation rate exceeds the value of this rate under natural conditions by several orders of magnitude, collisions are an important factor which sharply decreases the value of magnetization. Only the case of precipitation in distilled water, when the probability of aggregation of particles with their collision approach is small, can be an exception to this rule. Under natural conditions, the concentration of the precipitating solid phase plays the decisive role. For the conditions of deep-water lakes and coastal sea basins with the relatively high sedimentation rate its concentration is sufficient for intensification of the flocculation process, beginning from a certain depth. However, the quantity of material precipitating on the surface for areas distant from continents is too small and in these regions the role of collisions is of negligible importance. The magnetization of the precipitating suspension under conditions of intense flocculation has a linear dependence on the field and is defined by at least seven parameters, which characterize both magnetic and nonmagnetic particles. Such a multiparametric dependence of the magnetization value on the precipitation conditions is responsible for the practical impossibility of estimating the magnitude of the ancient geomagnetic field by the method of reprecipitation in view of the impossibility of adequately reproducing in the laboratory the precipitation conditions in the natural basins.