Mesozoic carbonatite complexes in Greenland

We report the results of the petrographic observations for the representative samples obtained during the field trip at the southwestern part of Greenland. The Tikiusaaq carbonatite complex contains REE carbonate minerals in calcite carbonatites. The representative REE carbonate minerals are strontianite (SrCO3) and ancylite (SrCe(CO3)(2)(OH)H2O). Strontianite contains Ce and ancylite contains considerable amounts of La, Ce, Nd, respectively. Several Ba-bearing minerals occur in the Qaqarssuk carbonatite complex instead REE carbonates. The complex contains about 4 million tons pyrochlore ores (0.5 wt% Nb2O3). Ba-carbonate (Barytocalcite, CaBa(CO3)(2)) occurs as a major carbonate mineral and coexists with barite and Ba-Sr carbonatite. In contrast, apatite and REE carbonates occur as minor constituent minerals.