Magnetostratigraphy and sedimentology of the Jingchuan red clay section and correlation of the Tertiary eolian red clay sediments of the Chinese Loess Plateau

Abstract

A 325-m-thick loess and red clay sequence was recently discovered at Jingchuan, which is situated about 45 km north of the previously studied Lingtai section in the middle part of the Chinese Loess Plateau. The Jingchuan section is composed of 199 m of Pleistocene loess and 126 m of Tertiary red clay deposits. Paleomagnetic studies show that the Jingchuan red clay has a basal age of at least 7.7 Ma, which represents the oldest red clay deposits presently known in the Loess Plateau. Field observations and grain size analyses both suggest an eolian origin of the red clay, thus extending available records of the eolian deposits in the Loess Plateau from about 7.0 Ma to 7.7 Ma. Correlation of both pedostratigraphy and magnetic susceptibility records suggests that the late Cenozoic red clay records in the Loess Plateau have a general continuous nature, thereby providing potential for deriving long-term climatic evolution signals from this eolian loess and red clay sequence. Copyright 2001 by the American Geophysical Union.