Identification of weak anomalies: A multifractal perspective

•Two types of weak geochemical anomalies are presented.•The current method could not directly process the data containing negative values.•The background value influenced the resulting singularity index.•A modified algorithm for estimation of the singularity index is introduced.•A Matlab program for estimation of the singularity index is coded.

Attention has increasingly been focused on weak geochemical anomalies. In this paper, the singularity mapping technique, a powerful multifractal tool to identify weak anomalies, is presented. The original algorithm for estimation of the singularity index could not directly process the data containing negative values, and the resulting singularity index is influenced by the background value. A modified algorithm for estimation of the singularity index is introduced to overcome these shortcomings, and a Matlab program is coded for estimation of the singularity index, using both the original and modified algorithms. The advantage of the modified algorithm is demonstrated using a case study from Chaobuleng Fe polymetallic district, covered with grassland, in Inner Mongolia of northern China.