Carbonatites in China: A review

There are 27 known occurrences of carbonatites in China. Brief descriptions are given of all occurrences including geographical coordinates, geological setting, associated rocks, carbonatite forms, ages, mineralogy, mineralisation, and carbon and oxygen isotopic data. About half of the occurrences lie along the margins of orogenic belts and the rest close to the margins and within tectonic blocks. All appear to be located on, or near to, major intraplate fractures. All the major carbonatite types are represented, including major complexes associated with alkaline silicate rocks such as ijolite, nepheline syenite, etc. several comprising dyke swarms, with or without associated silicate rocks, and extrusive carbonatite complexes. Several of the occurrences that are interpreted as being extrusive are problematic, three of these being Proterozoic in age and having field relationships which are difficult to interpret. Nineteen carbonatites have been dated and 15 of these give dates lying in the range 4–265 Ma. Two occurrences give Proterozoic dates, but a further three undated occurrences are considered to be Proterozoic, based on their field relationships. Dating of the Bayan Obo complex indicates emplacement of carbonatite dykes at 2070 Ma, but the complex appears to have been affected by four subsequent periods of mineralisation. Three occurrences are being mined for REE, and Fe, P and vermiculite are also being produced.