Abstract:This paper reports a new type of high temperature REE-rich barytocalcite, which occurs in REE-enriched alkaline carbonate veins in Songxian County, Henan Province, East Qinling. The molecular formula of the studied barytocalcites is Ba1.04Ca0.81Sr0.14(CO3)2 (Sr-barytocalcite) based on Stoichiometric calculation using the major element compositions. LA-ICP-MS analyses show high concentrations of Na, K, Fe, Mn, Pb, Y and REEs in the barytocalcite. The total REE concentrations of the barytocalcites are up to 4 080×10-6, which generally show LREE-enriched and HREE-depleted patterns. Contrasting to sedimentary barytocalcite formed in low temperature, backscattered electron images suggest that the studied barytocalcites have two types of high-temperature textures intergrowing with aegirine augite or with quartz + calcite + apatite. The intergrowth of orthomorphic barytocalcite with primary calcite suggests that they were formed in the early stage of alkaline melt evolution, likely crystallized in a carbonate and silicate immiscible environment. The later stage calcites were found in barytocalcites and aegirine augites in patch shape, implying a carbonate metasomatic stage. The assemblage of aegirine augite + K-feldspar + albite + pyroxene + apatite +calcite + quartz + barytocalcite is consistent with that in carbonatites. The features of high Ba, Sr and REE content in the studied carbonatites are also of high similarity to well-known large-scale REE-rich carbonatite ore deposits (e.g., the Maoniuping REE deposit). Together with detailed geological features of the alkaline carbonate veins, the results obtained by the authors could provide a general guideline for exploration of carbonatite REE deposits in the East Qinling region.