MODELS OF INCLINATION SHALLOWING DURING SEDIMENT COMPACTION

Microscopic models were constructed of compacting sediment which lead to inclination shallowing of the magnetic remanence. The models can be classified as 1) rotation of elongated magnetic grains to more horizontal orientations; 2) rotation toward the horizontal of flat nonmagnetic fabric grains to which smaller magnetic grains are attached; 3) randomization of the sediment by grain rotations which lead to decreased intensity of magnetization and possibly also to inclination shallowing; and 4) finally, it is shown that the initial within-sample dispersion of the magnetic moments dampens the amount of inclination shallowing of all the models and transforms any form of microscopic mechanism to an equation of a standardized form. Results show that considerable randomization is needed to offset the increased intensity due to higher concentrations of magnetic particles caused by compaction. If random rotations of the grains are biased toward rolling about horizontal axes and the randomization is sufficient to cancel the effect of greater concentrations, then the random grain rolling due to the compaction would give rise to considerable inclination shallowing. -after Authors