<p>Granite, a key archive for formation and evolution of continental crust, has a classification scheme that serves as the cornerstone for understanding its source nature, petrogenetic mechanism, and tectonic setting. By reviewing classic papers for granite classification, this paper presents a systematic evaluation of core advances in granite classification research. In general, granite classification schemes can be outlined into two major categories. One is the descriptive classifications, based on mineral assemblages, geochemical parameters, or stoichiometry; representative schemes include the felsic mineral paragenesis classification, the petrochemical triple-parameter classification, and the cation-parameter classification. The other is the interpretative classifications, aimed at revealing source nature, magma genesis, or tectonic environment; representative schemes include the Itype and S-type source classification as well as the tectonic classification. Each of these schemes has varying degrees of advantages and disadvantages, and a long-standing consensus remains challenging, primarily due to the following two problems: (1) the typically continuous compositional variation of granites, lacking clear boundaries. This is closely related to the complexity of magma source compositions and magmatic processes. Petrogenetic processes such as partial melting, fractional crystallization, restite entrainment, magma mixing, and assimilation can all lead to continuous compositional changes; (2) granites represent the minimum melt composition in silicate systems. Whether granites were derived from the fractional crystallization of mafic magmas or the partial melting of crustal sources, their compositions converge highly in the silica-rich end-member (SiO2>70 wt.%). This makes it difficult to distinguish granites from different sources in this range, independent of tectonic setting. Although the “endless quest” for a unified granite classification scheme continues, this research journey has profoundly deepened our understanding of the source-genesis-tectonic linkages in granite petrogenesis, promoting the transition of granite petrology from “field nomenclature” through “tracing the source” to “decoding the process”. Therefore, future studies of granite classification require the integration of multi-scale parameters to weigh the variables between descriptive and interpretative aspects from the two key elements of source and process, providing sophisticated constraints on the causal relationships between granite petrogenesis and continental crust formation. It must be emphasized that the classification of granites is only the preliminary stage of their research, whereas understanding their petrogenesis is the ultimate goal. This necessitates the rational identification of source rocks with diverse properties and the comprehensive characterization of magma production and differentiation processes—specifically, the partial melting of source rocks and the fractional crystallization of felsic magmas, as well as the enrichment of melt-mobile incompatible elements during these processes.</p>

On classification of granites

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发表日期：

2025年10月22日

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Peng Gao,
Yongfei Zheng

摘要

Granite, a key archive for formation and evolution of continental crust, has a classification scheme that serves as the cornerstone for understanding its source nature, petrogenetic mechanism, and tectonic setting. By reviewing classic papers for granite classification, this paper presents a systematic evaluation of core advances in granite classification research. In general, granite classification schemes can be outlined into two major categories. One is the descriptive classifications, based on mineral assemblages, geochemical parameters, or stoichiometry; representative schemes include the felsic mineral paragenesis classification, the petrochemical triple-parameter classification, and the cation-parameter classification. The other is the interpretative classifications, aimed at revealing source nature, magma genesis, or tectonic environment; representative schemes include the Itype and S-type source classification as well as the tectonic classification. Each of these schemes has varying degrees of advantages and disadvantages, and a long-standing consensus remains challenging, primarily due to the following two problems: (1) the typically continuous compositional variation of granites, lacking clear boundaries. This is closely related to the complexity of magma source compositions and magmatic processes. Petrogenetic processes such as partial melting, fractional crystallization, restite entrainment, magma mixing, and assimilation can all lead to continuous compositional changes; (2) granites represent the minimum melt composition in silicate systems. Whether granites were derived from the fractional crystallization of mafic magmas or the partial melting of crustal sources, their compositions converge highly in the silica-rich end-member (SiO2>70 wt.%). This makes it difficult to distinguish granites from different sources in this range, independent of tectonic setting. Although the “endless quest” for a unified granite classification scheme continues, this research journey has profoundly deepened our understanding of the source-genesis-tectonic linkages in granite petrogenesis, promoting the transition of granite petrology from “field nomenclature” through “tracing the source” to “decoding the process”. Therefore, future studies of granite classification require the integration of multi-scale parameters to weigh the variables between descriptive and interpretative aspects from the two key elements of source and process, providing sophisticated constraints on the causal relationships between granite petrogenesis and continental crust formation. It must be emphasized that the classification of granites is only the preliminary stage of their research, whereas understanding their petrogenesis is the ultimate goal. This necessitates the rational identification of source rocks with diverse properties and the comprehensive characterization of magma production and differentiation processes—specifically, the partial melting of source rocks and the fractional crystallization of felsic magmas, as well as the enrichment of melt-mobile incompatible elements during these processes.