末次间冰期以来黄土中伊利石结晶度的变化与古环境

对环县、长武和渭南3个剖面末次间冰期以来黄土-古土壤样品进行了粘粒（0和S1的KI值自西北向东南呈现逐渐增加趋势，而黄土L1层仅在最南部的渭南剖面呈现较高的值，环县和长武剖面差异不大，均呈现较低的值。综合分析影响黄土KI值变化的各个因素后，认为风化成壤作用可能是影响黄土-古土壤伊利石结晶度指标变化的主要因素，可以作为东亚夏季风环流强度演化的指标。

VARIATIONS OF ILLITE CRYSTALLINITY IN THE CHINESE LOESS DEPOSITS SINCE THE LAST INTERGLACIAL PERIODS AND PALEOCLIMATIC SIGNIFICANCE

Spatial and temporal variations of illite crystallinity (KI, Full width half maximum of illite diffraction peak at 1.0nm) were investigated on the Results indicate that KI values in the Changwu (CW, 35°12'N, 107°48'E)and Weinan(WN, 34°18'N, 109°30'E) sections is higher in the paleosols (S0 and S1) than in the loess units(L1), showing loess-paleosol alternation, similar to the pattern of magnetic susceptibility(MS). In the Huanxian section(HX, 36°37'N, 107°19'E), the contrast in the KI values between paleosols (S0 and S1) and loess units is less, but bottom of paleosol S1 still has higher ratios than other units. Spatially, the mean KI values of each of the stratigraphic units (S0 and S1) generally display a southeastward increase along the NW-SE sections, similar to the pattern of MS. In the loess units (L1), the mean KI values between Huanxian and Changwu sections show less difference and are rather lower, but the higher mean KI values exit in the Weinan Section.Results also show changes of the KI values in the three sections could not affected substantially by the dust provenance, eolian sorting and sedimentation rate. Since spatial changes in the KI values are overall similar to the present day climate and the past climates, we therefore those changes of the KI values are primarily caused by in situ pedogenesis and chemical weathering, and these propose changes reliably document changes in the intensity of the East Asian summer monsoon. Relatively, the KI values are not more sensitive to climate change than other summer monsoon indexes, such as MS, Rb/Sr and Fed/Fet. The KI values of the paleosol S0, S1 in the Weinan and Changwu sections, and the loess L1 in the Weinan section could effectively recorded the changes of East Asian summer monsoon. In those units, loess L1 of the Weinan section is the weakest developed unit, with the MS values of 125.3×10-8m3kg-1. Tentative estimates for the unit yield a mean annual precipitation of about 586mm based on the climofunction for paleorainfal from Song et al.(2012,2013). This result indicates that the precipitations for the changes of KI values in Weinan L1 unit are similarity with that of the modern pedology.