Multi-element association analysis of stream sediment geochemistry data for predicting gold deposits in south-central Yunnan Province, China

The use of traditional statistical and new methods of spatial analysis can provide suitable indicators of geochemical element dispersion, and aid in targeting potential areas for mineral exploration. A case study involving the analysis of stream sediment geochemistry data from an area in Yunnan province, South China, is presented. The area has two known areas of gold deposits where several mines are present. The study starts with an appraisal of the descriptive statistics of the data. Geological studies were conducted in the study area to obtain a thorough, ore geology of known gold deposits, and understanding of the regional geology mineralization, and to determine the mineral deposit model. Most of the GIS analysis was done using the stream sediment geochemical data. An inverse distance weighting interpolation algorithm was used to convert the point data to continuous surface (grid) maps for each element. Principal component analysis (PCA) was used to compress the information to a few maps and to assist in determining multi-element associations. The study revealed that most of the high element concentrations in stream sediments were found in the Ailaoshan metamorphic belt. Gold deposits were found to be associated with ultramafic intrusives within the Ailaoshan metamorphic belt and the ultramafic instrusives are associated with principal component images that represent multi-element associations related to gold mineralization. The first two principal components possibly represent two different types of gold associations and phases of mineralization. The study demonstrates the usefulness of applying PCA to geochemical data to produce maps that reveal different associations useful for gold exploration.