Determination and classification of geochemical anomalies based on backgrounds and cutoff grades of trace elements: A case study in South Nanling Range, China

Determination and classification of geochemical anomalies is an important step on geochemical exploration. A method called seven levels' classification of geochemical anomalies is presented to determine and classify geochemical anomalies based on backgrounds and cutoff grades of trace elements. The geochemical backgrounds of trace elements resulted from weathering can be described quantitatively by empirical equations in China. Cutoff grades of trace elements are proposed and compiled here. The seven levels' classification method is an objective, distribution free, multivariate, unfixed method and is tested in South Nanling Range, China. Anomaly areas of trace elements are well consistent with their ore-forming geological bodies spatially. Deposits locate generally within their anomaly areas with levels larger than 3 in seven levels' classification. In order to calculate geochemical backgrounds and anomaly levels of trace elements conveniently, GBAL software is developed.