Details of Magnetic Polarity Transition Recorded in Chinese Loess.

Abstract

The paleomagnetism of the loess unit L8 in Xifeng section of the Chinese Loess Plateau has been studied to determine the behavior of the Matuyama-Brunhes transitional field. Three primary results have been obtained. (1) The M-B transition is located in the low part of L8 and the time duration of this transition defined by directional changes is estimated to be about 3, 600 yrs, whereas the intensity changes last about 8, 000 yrs, both of the estimations being based on the SPECMAP δ18O time scale (IMBRIE et al., 1984). (2) The morphology of the M-B transition field is characterized not by a single reversal course, but at least by three reversals and one aborted reversal course. The VGP paths obtained are not consistent with a non-dipole axisymmetric field. (3) The geomagnetic fields during this transition seem to have the configurations that dipole field component is at least comparable to the non-dipole ones in magnitude, which does not support the commonly-accepted viewpoint.