A new stratification of the Dachai Pleistocene section, Xiangfen, Shanxi China
山西襄汾大柴更新统剖面划分的新观点

The magnetostratigraphic study on the Dachai section which is located in the Dingcun Paleolithic sites of the Xiangfen County,Shanxi province reveals that the polarity boundary between the Matuyama and Brunhes appears at about 45 m depth of the section.Magnetic susceptibility(MS)correlation result shows that this 45 m-depth position is right in the upside of S8 layer.Consequently,a conclusion can be drawn that the stratigraphic boundary between the Early Pleistocene(Q_1)and Middle Pleistocene(Q_2)should be at the 45 m depth,not the traditionally suggested 80m.This new division plan based on the paleomagnetic studies has significant meanings to correlations among the Dingcun Paleolithic sites and final determination of the age of Dingcun group.At the lower part of the Dachai section MS is characterized by relatively low values and variations.According to its deposition conditions and sediment characteristics,the authors think this sediment is loess formed in water.At the same time,the rock magnetic results demonstrate that magnetite,hematite and thermal-unstable maghemite are the most important magnetic minerals in the Dachai sediments.Magnetite and hematite both are the high-thermal-stable magnetic carriers.