Loess stratigraphy in Central China

Loess sequences in central China provide a detailed record of climate changes during the last 2.5 million years. At least 44 major shifts from glacial to interglacial conditions occurred during this time in China. Prolonged loess deposition lasting more than 40 millennia occurred eleven times with only four of these intervals in Brunhes Chron. The climate oscillations took place with increased frequency between 2.4 and 0.5 Ma compared to the last half million years. Major shifts toward cooler and drier climates occurred at about 2.4 Ma, 1.2 Ma, and 0.5 Ma, while less pronounced shifts are dated to 1.65 Ma, 0.8 Ma and 0.2 Ma. Three of the last four reversals of the earth's magnetic field whose lithostratigraphic position has been detail, are recorded in a glacial deposit. The low field magnetic susceptibility of loess and soils which reflects the concentration of ultrafine magnetite is related to the degree of pedogenesis and serves as a proxy measure of climate. The accumulation rate of the magnetite was fairly constant throughout the last 1.2 million years and can serve as a measure of time. Susceptibility records from localities near Xifeng and Luochuan, located 160 km apart are compared and used to define informal lithostratigraphic units in the Loess Plateau of China.