Magnetostratigraphy of a Late Miocene-Pliocene loess-soil sequence in the western Loess Plateau in China

Abstract

Eolian deposits of Pliocene age have never been reported from the western Loess Plateau in China. Here, a 73.7 m eolian sequence is dated using magnetostratigraphic method and micromammalian fossils. The polarity zonation correlates with the geomagnetic polarity timescale (GPTS), from Chron 3Br. 1r to Chron 2An.3n, indicating an age from 7.10 to 3.52 Ma BP. The sequence is characterized by clear expression of eighty-four pairs of loess and soil layers while individual soils are basically indefinable for the eolian deposits of the same age in the eastern Loess Plateau, suggesting that the later has experienced other geological processes. This sequence extends the upper limit of the previously reported Miocene loess-soil sequences at Qinan into the Pliocene, about 3.52 Ma BP. Copyright 2004 by the American Geophysical Union.