通过对黄土高原腹地甘肃合水MJY全新世土壤剖面磁化率、全铁、TOC、Rb、Sr和Rb/Sr等气候代用指标的测定分析,揭示了与全新世环境变化相对应的成壤过程,并在此基础上,阐明黄土高原中部地区环境资源变化对人类活动的影响。认为全新世早期,黄土高原中部地区气候比较温和干燥,风尘堆积速率降低,地表植被以草本为主,并有一定的生物风化成壤作用,土壤发育表现为边沉积边成壤;全新世中期,气候温暖湿润,地表植被发育,生物风化成壤作用大于风尘堆积作用,随着沉积和成壤的继续,土壤层深厚,形成古土壤层(S0);全新世晚期,气候开始恶化,干旱少雨,植被退化,沙尘暴频繁发生,风尘堆积作用大于风化成壤作用,土壤退化形成的现代黄土层(L0)覆盖了土壤(S0)使之成为埋藏古土壤。在寺洼文化时期(3250-2520 aB.P.),由于气候干旱使环境资源恶化,土壤退化严重,土地资源利用方式和文化形态从原始的农耕文化转向游牧类型文化。
Analyzing magnetic susceptibility, total Fe, TOC, Rb and Sr in cultivated soil of the MJY -a site in Heshui in Gansu province, the relation between the proceeding of pedogenesis and the climate change of Holocene was opened out. On this base, the condition of soil and land resource in the hinterland of the Loess Plateau and the influence with human .activities were expounded. In the early stage of Holocene, the dust deposition was reduced because of the moderate and dry climate, and the biological weathering was beginning. In the mid - stage of Holocene,the climate got warmer and wetter, so the speed of pedogenesis was quicker than the dust deposition. With continued of soil layer thickening, paleosoil layer (So ) was formed. In last period, because the climate turned to worse, the dust - fall frequently happened, and then the speed of the dust deposition was quicker than the pedogenesis, which formed recent loess (L0) covered soil (S0) and made SO became the buried paleosoil. The climate has been dry from the period Siwa Culture (3 250 -2 520 a B. P. ) , which made environmental deterioration and soil degeneration, land use of arable farming was replaced largely by pastoral farming.