Preliminary magnetostratigraphy of the red clay underlying the loess sequence at Baoji, China

Abstract

Magnetic remanence and bulk susceptibility measurements are reported from 93 samples spanning the uppermost 27m of the Red Clay underlying the loess sequence at Baoji, Shaanxi province, China. If a new, previously undetected, short (about 20ka) excursion or reversed interval near 3.3Ma be accepted, then a reasonable fit to the standard time scale emerges. A linear accumulation rate of 1.5cm/ka is implied and the correlation coefficient is 0.992. No significant hiatus occurs between the Red Clay and the overlying loess, so the 27m investigated reach back to about 4.3Ma. Fourier analysis of the bulk susceptibility data yields a strong peak near 400ka in agreement with astronomical calculations of the orbital parameters responsible for climatic forcing.