Improving the method of U-spatial statistics by modeling the enrichment index of stream sediments for the purpose of introducing geochemical anomalous areas of epithermal gold type mineralization

Geochemical halos are regions around mineral deposits where the concentration of elements decreases to a constant level called the background. In the meantime, in order to find out the unusual concentration of elements (anomaly), the upper limit of the background limit (threshold value), must be determined. To achieve this goal, it will be effective and efficient to use new exploration methods. In this article, to draw the potential areas of stream sediments, modeling the data of element enrichment index with the U-spatial statistic method has been used. According to the morphological characteristics of the stream sediments environment, the origin of the samples taken from these sediments goes back to the upstream of the watersheds, so the analysis of the geochemical data of these samples is different from the rock environments. A preliminary modeling should be done on the data to consider the geological features upstream of the samples. The isotropic nature of the window in which the weighted averaging is performed in the algorithm of the U-spatial statistics method is such that all the upstream and downstream samples participate in this averaging and this case can be the point considered a significant weakness for this method. To reduce this weakness and to improve the method, first by considering the upstream rock units, the element enrichment index was obtained on the raw data, and then the U statistics was modeled on these indices. With this method, while the indices of the area were more accurately identified, the false potential areas obtained from the U-spatial statistic method were also removed and the results were acceptable and close to the field realities for determining mineralization potential areas.