Paleosandstorm characteristics and lake evolution history deduced from investigation on lacustrine sediments-The case of Hongjiannao Lake, Shaanxi Province

摘要

Sediment cores from desert lakes serve as good records of the frequency and intensity of sandstorms in history. By multi-proxy analysis of grain-size, magnetic susceptibility, TOC and Rb/Sr ratio, the paleosandstorm characteristics and lake evolution history in Yulin Area for the past 80 years, are discussed in this article. It is revealed that Hong-jiannao Lake formed in about 1928 A.D. and in its stage sandstorms were prevalent with three extremes place in 1936 A.D., 1939 A.D. and 1941 A.D.. During the expansion period of 1952 - 1960 A.D., inflow waters to the lake increased sharply and a lot more weathered materials were carried into the lake. The frequency and Intensity of sandstorms have reduced a lot since 1960s and the "double peaks" feature of the grain-size frequency curve has changed into the "single peak" feature. Study on the catchment ecology of the lake shows that the occurrence of sandstorms has been effectively restrained by the forest plantation and water and soil conservation.