Identification of weak geochemical anomalies using robust neighborhood statistics coupled with GIS in covered areas.

Abstract: Robust neighborhood statistics, such as median, median absolute deviation (MAD), and local relative enrichment index (LREI), were used to model spatial variations of geochemical landscapes and to recognize weak geochemical anomalies in covered terrane by means of a case study from the Chaobuleng Fe polymetallic district covered by grassland, in Inner Mongolia (China). The results of this study show that: (1) the robust neighborhood statistics of median and MAD can well discriminate between different geochemical landscapes (with outcrop areas characterized by high values of Fe2O3, and the covered areas linked with a low value of Fe2O3) and delineate the boundaries between the outcrop and covered areas; (2) the LREI can reduce the effects of covers such as soils and grassland on geochemical mapping and identify the weak geochemical anomalies caused by decaying and masking effects of covers; and also (3) the resulting neighborhood statistics are influenced by the size of neighborhood. [Copyright &y& Elsevier]