Geological and geochemical characteristics of the Miaoya syenite-carbonatite complex, Central China: Implications for the origin of REE-Nb-enriched carbonatite

•Formation of Miaoya carbonatites involving both crystal fractionation and fluid immiscibility.•Both carbonatites and syenites were fractionated from carbonated syenitic magma.•REE enrichment are associated with fractionation processes of parental calcium carbonatite.