Abstract

Separation of geochemical anomalies from background plays an important role in the study of exploration geochemistry. The limitations of commonly used methods are not taken into account spatial correlation, variability and the unsatisfactory of the statistical assumption of the normality of geochemical data. For solving these limitations, an indirect method for the separation of geochemical anomalies is proposed based on anomaly separation of local Moran’s Ii values using robust statistics in this study. The experiment was carried out using 1481 samples collected from Jiurui copper prospect (southeast China). The steps for the anomaly separation are (i) spatial association and variability were fi rst analyzied by means of Moran scatterplots at six spatial scales (2, 4, 6, 8, 10 and 12 km) using both raw data and Box-Cox transformed data; (ii) local Moran’s Ii was used to measure spatial autocorrelationat these six local scales; (iii) anomalous separation was fi nally performed using the MEDIAN ± 1.5*IQR (IQR: interquartile range) rule on local Moran’s Ii values. The results show that geochemical anomalies are mostly concentrated around known ore-deposits, according the objective reality and a strong correlation with known ore-deposits in Jiurui copper prospect.

Authors and Affiliations