| X-ray fluorescence spectrometry (XRF) is an important part of nuclear geophysics and application in nuclear technology, which uses a radioisotope source or X-ray tube, emitting rays to test substance. After the substance excited, it emits the particular X-ray. And than the energy and exposure rate of X-ray is measured by instrument to confirm what the X-ray is.XRF starts in the early 1950s as a routine analysis mean. It has become one of the analytical tools measuring geochemical samples due to its simultaneous multi-element determinatioin, high sensitivity, low detection limit and good reproducibility, as well as simple preparation and low costing. Has been widely used in metallurgy, geology, chemical industry and a variety of analytical chemistry laboratories, especially XRF has been to promote the application in terms of Geology and Mineral Resources. XRF method in the Geology and Mineral Resources, Ministry of Metallurgical Industry, the Chinese People’s Armed Police Gold Command and other departments have been widely used, and has made great achievements in terms of deposit exploration of gold, silver, copper, tin, lead and zinc.Dashui Gold Deposit in Maqu, Gansu province, has exploited 20 years since it had been found at 1990s, and now this gold deposit is in its crisis because of lacking more continuous resource, so it is time to prospect the buried ores around this area. As for the study area of Dashui Gold Deposit is covered of soil, few bed rocks and geological phenomena can be found, it is inevitable to choose soil geochemical survey to explore mineralizations. However, measurement of soil samples is another vital thing because the data right or not is related to the success of prospecting new gold mine. Therefore, we choose XRF to analyse geochemical samples.In this study, we established a wavelength dispersive X-ray fluorescence spectrometry (WDXRF) curve to test soil samples. Then, the geochemical data were handled by a multivariate statistical analysis method in order to explore the relationship of elements with Au. Finally, anomaly threshold was calculated by traditional and fractal method, using MAPGIS and Surfer software to draw geochemical maps to evaluate anormal targets. After the research, some conclusions were obtained.(1) In this study, the established curve in WDXRF reached relerant regulation. It had low detection limit, high precision and well accuracy.(2) Through correlation analysis, cluster analysis and factor analysis, we knew that Au mineralization had independent characteristic, and had good relationship with Ag, As, Co and W element. In cluster analysis, Au, Ag, Co and W gathered, reflecting the combination of low temperature mineralization. Through factor analysis, we cleared that the enrichment of Au was a result of superposition of multiple phases and controlled by the structure movement.(3) From the result of traditional and fractal method processing the geochemical data, we realized that the fractal method was superior to traditional method when they used to calculate the anormal threshold.(4) Geochemical maps were made by two methods, finding that both methods found the anormal area in the same location with Au、Ag、Co、Cu and W elements. This proved the validity of fractal method. Also, the anormalies of Ag, Co and W element was the same with Au.(5) Three prospecting targets were found by conecting the integrated anormaly map with geological structure feature. The first mineralization was in the north of the working area, the rear of B and D line of the middle. The second place was in the front of E line,the middle of F line and rear of the G and H line, presenting a north-south beaded distribution. The third area was a independent abnormal place in the partial rear of L line, the front of D-line and E-line.(6) The Dashui Gold Deposit had a potential of mineralization through the comprehensive study. If allowed, the anormaly area should be verificated by engineering, guiding the further prospecting mission. |
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