Xiaoyong Wang

PARTICLE SIZES, MAGNETIC PROPERTIES AND ORIGINS OF LOESS DEPOSITS FROM HUANGNISHAN HILL IN NANTONG, JIANGSU PROVINCE: PARTICLE SIZES, MAGNETIC PROPERTIES AND ORIGINS OF LOESS DEPOSITS FROM HUANGNISHAN HILL IN NANTONG, JIANGSU PROVINCE

Huangnishan hill is located in the southern area of Nantong City,Jiangsu Province. In this paper,we studied magnetic and granulometric characteristics of loess deposits from the Huangnishan hill and the origin of loess. The sediments are dominated by silty clay,and finer than those of both the Xiashu loess in Zhenjiang and the loess in the Chinese Loess Plateau. Huangnishan loess is similar to Xiashu loess in magnetic property,implying that the Huangnishan loess is the same as the Xiashu loess in Zhenjiang area,which is of aeolian origin. The fluctuation of magnetic parameters indicates that paleoenvironmental changes were recorded in the loess,too. The lower content of fine-grained ferrimagnetic minerals and higher S-100 values of the deposits in comparison to the Xiashu loess suggest that the Huangnishan loess experienced a lower degree of pedogenic alteration than that of the Xiashu loess in Zhenjiang.

A modified depositional hypothesis of the Hanjiang Loess in the southern Qinling Mountains, central China

Geomorphologically, alluvial deposits in river systems are expected to be older on higher terraces than on the lower terraces. However, loess deposits of aeolian origin may also occur on the surface of terrace systems and as seen in the Chinese Loess Plateau (CLP). Such loess is continuously, rather than episodically deposited. This study presents numerous dating results of loess cover on the Hanjiang River terrace system in the southern Qinling Mountains, an atypical loess deposit belt outside of the CLP. We name this “Hanjiang Loess”. Results indicate that the Hanjiang Loess deposited on the high, middle, and low terraces are also the oldest, old, and most recent, respectively, apparently analogous with alluvial expectations. We thus propose a modified depositional hypothesis, whereby terrace loess reflects the deposition of aeolian loess and other material, subsequent fluvial reworking. This depositional hypothesis should also be applicable to loess deposits on the river terraces in the Xiashu Loess, Quaternary Reticulate Red Clay, and Quaternary Red Clay in southern China, and other atypical loess areas outside of the CLP.