Abstract:

      This paper gives some results from multi-purpose geochemical mapping in the Hetao area，Inner Mongolia. The soil of the Hetao area is rich in alkaline materials such as Mg and Ca. Attention should be paid to the mineralization of some dispersed elements such as Ga,Ge and Tl in Langshan polymetallic mining field. The Wulashan.Daqingshan is the favorable area for prospecting greenstone type gold deposit. Element contents of the soil with the granularity in <20 mesh reflect the geochemical characteristics of Hetao area. Parent material is the first factor that determines the elements’concentrations. For example, piedmont alluvial fan of Langshan is an abnormal sedimentary assemblage mainly with polymetallic material and dispersed elements. The cities in Hetao area are all characterized by element anomalies of Pb,Hg,C,Ag,Au,P,Cd and so on. In ancient lake area and modern Wuliangsu lake, F,Mo,U,CaO,MgO,Sr,C and I appear to positive anomaly, and SiO₂  negative anomaly. Meanwhile, modern Wuliangsu lake sediments are rich in organic carbon,N,P and Se with low pH; and the ancient lakes are on the contrary. Fluorosis areas in Hetao have the same distribution with ancient lake, old channel and Cretaceous formation, and epidemic degree is proportional to volume of underground water with high fluoride. Arsenic poisoning is relevant to the interaction of total As and As₃₊,and the valence of As affects the arsenic poisoning. The higher the As ₃₊ content is, the more serious the arsenic poisoning is.

Key words: multi-purpose geochemical mapping, Hetao area, Inner Mongolia, ancient lake, fluorosis area, arsenic poisoning