地质科技通报 (Sep 2024)
Alteration mineral identification and metallogenic prediction of porphyry deposits based on geochemical data
Abstract
Objective Traditional exploration and geochemical studies have primarily focused on the extraction, interpretation and evaluation of metallogenic element anomalies. This approach, however, overlooks valuable ore prospecting information, which may be provided by other major and trace elements. Consequently, altered minerals cannot be effectively extracted, and geochemical data is under utilized for ore prospecting. Therefore, the author extracts alteration minerals from a mineralogical perspective and make metallogenic prediction. Methods This paper introduces a new method for extracting alteration minerals based on geochemical data and the stoichiometric ratios of different elements in the mineral chemical formula, referred to as the general element ratio analysis. Results Based on geochemical data obtained from 1∶ 25 000 debris geochemical survey in the Gaoshishan area of the Beishan orogenic belt, results show that sericite, K-feldspar and other alteration minerals are closely related to porphyry deposits, which can be effectively identified from SiO2, Al2O3, Na2O, K2O and other data. The mapping results reveal that sericite is mostly distributed along the intrusion's margins, while K-feldspar is mainly concentrated in the center of theintrusion. Then, based on the ore-controlling factors and ore-prospecting information, such as alteration minerals, magmatic rocks, structures, and traditional geochemical anomalies. This study further conducts metallogenic prediction for the Gaoshishan area using the weight-of-evidence method, delineating five target areas. Conclusion The alteration information extracted in this study has been validated through field investigations confirming that the proposed method is feasible and can provide critical prospecting insights beyond those offered by traditional metallogenic prediction methods.
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