干旱区生态环境知识资源中心

Through the measurement of the susceptibility anisotropy and the statistical analysis of the susceptibility ellipsoid’s major axis of the sand dune sediments recently found in Jiujiang A Xingang in Jiangxi Province, this Papers uses the variation features of the magnetic fabric the different strata to obtain the patterns of paleowind direction and the rules parameters in the different strata to obtain the patterns of paleowind direction and the rules governing its evolution. (1) During the whole period the dominant wind direct on is NW NNW-SSE with some minor internal changes in wind direction and intensity. The most important change occurs in the second sand stratum when the wind direction shifted to NE-SW. That shows a relatively stable sedimentary environment. (2) In the second, fifth and sixth sand strata the values of P, F, and L are high, and the value of q is low. That corresponds to the coldest climate in the series. The intensity of the winter wind is the highest and the wind velocity is stable, corresponding to the development of large scale tabular and oblique bedding in these strata with coarser grain sizes and lower clay content. (3) During the Late Pleistocene, the extensive occurrence of aoelian sand dunes in the middle reaches of the Yangtze River correspond to the coldest and most dry climate, and also to the strongest wind energy, similar to that of the northern deserts and loess plateau regions. (4) This paper demonstrates that the hemispherical projection and the rose chart of the AMS major axis are easy and effective methods to analyze the variation patterns of the paleowind direction.