内蒙古东乌旗半干旱草原浅覆盖区土壤地球化学测量采样方法技术探讨

Soil geochemical survey and sampling in the semi-arid grassland of Dongwu banner, inner Mongolia autonomous region

内蒙古东部半干旱草原区广泛存在的各类风成沙对土壤地球化学测量有不同程度的干扰,通过东乌旗迪彦钦阿木钼银多金属矿区的研究工作,发现从残坡积层到有风成沙混入的残坡积层,矿化指示元素Pb、Zn、Mn、Ag、Mo、Sb、As出现不同程度的降低,进入腐殖层以后,这些元素含量进一步降低到只有残坡积层的1/2~1/5左右;特别是厚度大于10 m的古风成沙层存在时,它的上部及其上发育的腐殖层中,所有矿化指示元素异常全部消失。研究确定出草原浅覆盖区土壤地球化学测量的最佳采样粒级为-4目^+20目,最佳采样层位为残坡积层。同时,认为有必要对以往草原区获得的常规土壤地球化学测量成果的可利用性进行评估,以降低漏矿的风险。

The aeolian sand widely existed in the semi-arid grassland area of eastern inner Mongolia has obvious interference in the soil geochemical measurement.It was found that the mineralization indicated that Pb,Zn,Mn,Ag,Mo,Sb and As decreased significantly from the residual slope accumulation layer to the residual slope accumulation layer mixed with wind-formed sand.After entering the humus layer,the content of these elements further decreased to about 1/2 to 1/5 of the residual overlying sediment layer,especially in the upper part of the paleoaeolian sand layer with a thickness of more than 10m and the upper part of the humus layer,all the element anomalies disappeared.The study determined that the best sampling grain level of soil geochemical survey in the shallow overburden area of grassland was-4^+20 order,and the best sampling level was residual slope accumulation layer.At the same time,it is necessary to evaluate the results of conventional soil geochemical survey in the former grassland areas to reduce the risk of ore leakage.