The Study Of Geochemical Technology For Mineral Exploration In The Arid Gobi Desert Terrain, Beishan Mountains Area, Gansu

In order to find the suitable geochemical technology for mineral exploration in thearid Gobi Desert, the weight and elemental distribution of different fractions in streamsediments, soil and wind dust were systematically studied in Xaoxigong, Tiaoshanziand Laohushan areas, Beishan Mountains area, Gansu. It can be concluded that:1. The wind dust is widespread in the Beishan Mountains area. The streamsediments are most composed of -20 mesh fine grain and -80 mesh wind dust instream sediments mostly came from the distant sources;-4 ~ +80 mesh coarse winddust mixed with some near-rock chops and rock chops became less as the grain ofwind dust decrease. Therefore the wind dusts mainly disturb the distribution and theelement content in the -20 stream sediment and the -20 soil fraction.2. the vertical distribution of elements in soil profiles changes with differentareas, but overall the content of elements decrease gradually downwards. The trend ofelemental reduction downwards can be enhanced by the deposition of wind dusts. Inthe top soil, the enrichment and depletion of elements were mainly controlled by saltprecipitation.3. the author recommends the geochemical prospecting methods for arid Gobidesert landscape, Beishan Mountains area.The -4 ~ + 20 mesh coarse fraction was selected as sampling grain for analysisboth for stream sediments and soil, but different strategy was taken for individualmedium:Soil survey: the samples should be collected at weathered residual layer mixedwith variety of rock chops. The composed samples should be collected by mixingwith five sub-samples, which should keep apart from several meters to hundredmeters depending on the scale of surveys. The sample density for 1: 200,000 soilsurvey is 2 samples per square kilometer and for 1: 50000 soil survey 4-12 samplesper square kilometer.Sream sediment survey: the fine-coarse mixed stream sediment should be sampledin active water channel and composed of sub-sample. The sampling density for1:200,000 stream sediment survey is 1-2 samples per square kilometer and for 1: 50,0004-6 samples per square kilometer.In comparison with the study results of different media, it can be concluded that:soil is much widespread and easy to be collected and be suggested as main media forboth 1: 200,000 and 1: 50,000 geochemical surveys in the Beishan Mountains.