Geochemical Survey And Assessment For Laege Ore Camps--A Case History From Eastern Tianshan

From the studies it is concluded that the main and quantitative difference between large ore deposits or camps and small ones lies in the tremendous endowment and accumulation of elements for the formation of large ore deposits or camps. Thus, large ore deposits or camps are hosted by large-scale geochemical patterns - geochemical blocks. These large-scale geochemical patterns can be delineated by wide-spaced geochemical survey. Deep-penetration geochemical methods are developed for collection of signals from concealed deposits.These concepts and methods have been widely investigated for their usefulness and suitability for delineation of broad geochemical patterns and assessment for large ore deposits or camps.Northwestern China is a large unexplored or under-explored arid desert terrain, making up 22 % of total China's land territory. Into the new century, interest was rekindled by the discovery of a large porphyry copper deposit with copper reserves of more than 10 millions of tons in the eastern Tianshan mountainous belt, Xinjiang, northwestern China. In order to quickly get an overview of the mineral potential of the entire eastern Tianshan terrain, a large wide-spaced geochemical survey project was commenced in 1999 in area of 150 000 km2.(1) Soil geochemical methods (total analysis) and deep-penetration geochemical methods (selective leaching of mobile metals) are both used. The orientation study shows that wide-spaced sampling of the cemented sand can delineate large and clear geochemical patterns generated by metallogenic belts.(2) Geochemical atlas and interpretation geochemical maps with 33 elements using GIS were generated.(3) Seventeen geochemical blocks have been delineated. These include 6 Cu blocks, 4 Au blocks, 3 U blocks, 1 W block, 1 Au-Cu-Pb-Zn block and 1 Cu-Pb-Zn-Ag block.(4) From these geochemical blocks and geological settings the author found that 6 geochemical blocks are consistent with the known large ore camps, 11 blocks are newly discovered and very promising for new ore camps of copper, gold, uranium and tungsten.