磁化率各向异性测量在沉积学中的应用

Measurement of Anisotropy of Magnetic Susceptibility on Xiashu Loess and It's Implication to Sedimentology

本文利用磁化率各向异性来研究南京下蜀土的沉积组构。根据南京下蜀上的磁组构特征及其与华北黄土的对比分析，探讨了下蜀土的成因，并进而指出了磁化率各向异性测量对于沉积学的重要意义。

The measurement of anisotropy of magnetic susceptibility (AMS) is a newly developed method that is used to investigate the sedimentary fabric of the sediments. The measurement of AMS on the loess in Central China showed that the primary eolian loess and the secondary aqueous loess are different sediments which deposited in different medium-air or water, and there is distinct fabric from each other, so according to the difference we could distinguish the two sorts of sediments.On the bases of analysis on the theory and method to investigate the sedimentary fabric of loess -like sediment by the measurement of AMS, the paper attempts to use the method on the study of Xiashu loess in Nanjing. The results of the measurement show that the AMS of Xiashu loess is not clear, the percent age of anisotropy (P) is 1. 004<P< 1. 02, and it is relevant to foliation (F) closely, to lineation (L)hardly. Such a feature highly resembles with that of eolian loess in Central China.The measurement of AMS was initially used in the investigation of the sedimentary fabric of the solidified rocks. It is more simple, economical and accurate than the traditional method of slice analysis. As used in loess study, the measurement of AMS should have an important effect on the analysis of formation for some dispute sediments especially for the Quaternary sediments.