Dependence of Near-Surface Magnetic Susceptibility on Dust Accumulation Rate and Precipitation on the Chinese Loess Plateau |
| |
| Authors: | Stephen C Porter Bernard Hallet Xihao Wu Zhisheng An |
| |
| Institution: | Quaternary Research Center, University of Washington, Seattle, Washington, 98195-1360, f1;Institute of Earth Environmental Research, Academia Sinica, Xiying Road 22-2, Xi'an, 710054, China, f2 |
| |
| Abstract: | Magnetic susceptibility (MS) of surface sediment varies systematically across the Loess Plateau in central China, decreasing exponentially from >200×10−8 m3/kg at the northern margin of the Qinling Shan to ≤30×10−8 m3/kg near the southern margin of the Mu Us Desert. MS correlates highly with loess median grain size (r2=0.79), which decreases south-southeastward across the plateau. It also correlates with mean annual temperature (MAT) and mean annual precipitation (MAP) (r2=0.58 and 0.60, respectively), and with their product MAT×MAP (r2=0.83), which is considered a measure of potential pedogenic activity. Because regional isopleths depicting grain size and the primary meteorological parameters are nearly parallel, it is difficult to determine their relative influence on MS. A simple MS model, based on the observed spatial variation in loess thickness, permits quantitative assessment of the effect of the dust accumulation rate on the MS signal of surface sediment and isolates the likely role of climate in the production of magnetic minerals. The model suggests that 84% of the loess MS variance is dictated by the diluting effect of dust and 10–11% is associated with meteorological factors, primarily precipitation. The observed and modeled relationships support hypotheses that attribute variations in MS in the loess-paleosol succession to varying rates of dust deposition and in situ production of magnetic minerals in the accretionary soils, both of which are controlled by monsoon climate. |
| |
| Keywords: | Abbreviations: loessAbbreviations: paleosolsAbbreviations: ChinaAbbreviations: Loess PlateauAbbreviations: magnetic susceptibilityAbbreviations: paleoclimateAbbreviations: eolian dustAbbreviations: soil |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
