Contrasting granite metallogeny through the zircon REE composition: Perspective from data mining. (November 2020)

• Record Type: Journal Article
• Authors: Li, Xingyuan; Zhou, Yongzhang; Wang, Jun; Ye, Mao; Geng, Ting
• Is Part Of: Applied geochemistry. Volume 122(2020)
• Publication Date: 2020-11
• Subjects: Yanshanian granites -- Zircon REE -- Data mining -- Python programming -- Magma fertility -- South China; Environmental geochemistry -- Periodicals; Water chemistry -- Periodicals; Geochemistry -- Social aspects -- Periodicals; Geochemistry -- Periodicals; 551.9
• DOI: 10.1016/j.apgeochem.2020.104758
• Languages: English
• ISSNs: 0883-2927

Abstract

Abstract: Yanshanian magmatism develops well and has obvious metallogenic specificity in the Qinzhou–Hangzhou bays of South China. Zircon, in granite, has great potential in the study of metallogenic specificity. Moreover, with the development of in-situ zircon analysis technology, a significant amount of data on zircon composition has become available in recent years. Hence, to further elucidate the distinctive diagnostic signatures of zircon signatures regarding metallogenic fertility and the preference for metallogenic types of granites, this paper exhaustively explores all possible bivariate and ternary discrimination diagrams using a set of 13 rare-earth elements with published zircon data from Yanshanian, South China. This results in 4095 binary diagrams and 12, 485 ternary diagrams, ranked according to their success in classifying the training data. One-hundred binary graphs and 300 ternary graphs with the highest CH index values were selected, from which the graphs were picked out. The results reveal that there is no suitable diagram to distinguish between mineralization and barren granites. Further, in the diagrams to distinguish the type of mineralization, there are indeed some overlapping parameter ranges (such as Gd/Yb and Ce/Gd); however, it still can be observed that some binary and ternary graphs containing Eu or Ce (e.g. Eu/Gd, Eu/Tb and Ce/Sm) can discriminate between samples related to porphyry Cu and samples related to W–Sn (Sn). Some diagrams (i.e. Dy/Lu–Er/Lu, Gd/Dy–Er/Yb) also have been observed to distinguish between ore-forming types of granites, the underlying geochemical mechanism of which has not been fully understood. In addition, our results suggest that the linear discrimination analysis (LDA) method outperforms any of the traditional discrimination diagrams in discriminating ore-bearing and fertile granites. The results of geochemical data mining in this paper can be used as prospective indicators to provide a scientific basis for the study of Yanshanian hydrothermal deposits in South China. Moreover, the compositions of zircon are relatively simple to obtain, and the LDA methods described in this study could potentially be used as a useful exploration tool. Highlights: New discrimination diagrams were proposed by using zircon REE composition. Most discrimination diagrams related to Eu and Ce can distinguish the mineralization information of the parent rock. The linear discrimination analysis (LDA) method remarkably outperforms any traditional discrimination diagram.