Geochemical Methods For Semi-arid Grasslands

Stream sediments are used as the main sampling media in 1:200,000 Regional Geochemistry-Nation Reconnaissance Program (RGNR) covering an area of 6.5 million km~2.This method is greatly effective in prospecting for mineral deposits in the outcropping mountain-hill regions. However,this method are not effective in coveraged areas, such as in semi-arid grasslands in centre-eastern Inner Mongolia.Based on"Exploration Geochemical Methods for the Semi-arid Grasslands in Centre-eastern Inner Mongolia"-project supported by the China Geological Survey, the author carried out geochemistry research on geomorphologic landscapes,surface geochemical abundance and distribution,-in streams,at hilly semi-covered grasslands in Dong Ujimqinqi.The conclusions are as follow:1) The fraction of -120 mesh is effective sampling media for regional and follow-up geochemical surveys, 2) Sampling density of 1 sample per 1 sq km clearly delineate regional Ag-Cd-Pb anomalies around the known silver deposits, 3) Sampling density of 4 per km~2 is effective method for follow-up surveys. .