黄土不同指标的古环境意义探讨

 在确认“黄土也是古土壤”的前提下，对新近发现的位于黄土高原西北部沙漠黄土边界带的彭阳剖面进行了烧失量、色度、磁化率、粒度、CaCO3等环境变化代用指标的系统测试。通过建立土壤发育指数和红化指数，探讨了各指标与古土壤发育强度之间的关系。根据古土壤的发育强度，初步建立了800 ka BP生态脆弱区的高分辨率环境图谱。此图谱与公认的海洋氧同位素曲线、洛川剖面可以进行良好的对比，并揭示出更多的环境变化信息。

Study on Environmental Signification of Main Indexes of Loess

The Pengyang section situates in the desert-loess transitional zone on northwestern Loess Plateau.In premise of consideration of \!loess is also paleosol\" several environmental proxies related to soil-forming process have been tested,and a soil development index has been set up in this paper.Using the soil development index,the paleoclimatic change patterns with high resolution of the ecotone since 800 ka BP have been established,which revealed that the deserts expanded and approached the present region in about 820~810 ka BP, 700~680 ka BP,540~520 ka BP,390~360 ka BP,260~230 ka BP,120~110 ka BP and 40~30 ka BP.The northward movement of the subtropics took place in about 750~700 ka BP,500~450 ka BP and 110~100 ka BP.