Magnetic mineralogy of Chinese loess and its significance

Abstract

The topmost 16 metres of the loess section at Xifeng (central Chinese loess plateau), which cover the last 128000 years, consist of two palaeosol beds interlayered by a loess horizon.Hysteresis parameters, frequency-dependent, field-and temperaturedependent susceptibility show very similar and stable magnetic mineral constituents in both loess and palaeosol samples.The concentration and grain size of magnetite, maghaemite and haematite control the magnetic properties of Chinese loess.Susceptibility and loess thickness are closely related to geographic position and (present) climate across the loess plateau.The loess and palaeosol magnetic properties are largely controlled by the fine-grained magnetite formed in various quantities and grain sizes under the influence of pedogenesis during variable palaeoclimatic conditions.Therefore regional and global palaeoclimatic development during the last 2.5 Myr can be reconstructed from susceptibility records in the loess plateau.