Geologic anomaly analysis for space-time distribution of mineral deposits in the middle-lower Yangtze area, southeastern China

Abstract

A geologic anomaly is a geologic feature or structure that departs markedly from its surrounding environment with respect to composition, texture, or genesis. The analysis of geologic anomalies related to mineralization is based upon specific geologic factors and a combination of features, such as structural, temporal, and spatial, and draws upon special effects that are due to ore-forming processes. An analysis of the geologic anomalies in the, middle-lower Yangtze area in southeastern China has led to an interpretation of the relation between anomaly subtypes and the occurrence and spatial distribution of ore deposits. Consequently, the following conclusions have been reached: the type of anomaly reflects the controlling factors that led to the formation of iron, copper, and gold deposits in the area; sedimentary geologic anomalies are most closely associated with stratiform deposits; structral complexity anomalies are most closely associated with Cu−Fe−Au deposits; magmatic anomalies reflect geologic processes in which Fe and Cu elements were separated from magma and enriched into ores; and the geologic combination entropy anomaly is proposed as a comprehensive variable that is related to favorable ore-forming environments and that can serve as a quantitative index that can be used in mineral exploration.