ABSTRACT
A suite of carbonate and alkali-ultramafic complexes are found in biotite-hornblende gneisses of marginal part of Gyunggi gneiss complexes of Korean peninsula: Such carbonate rocks have never been reported in Korea. These complexes contain Fe-REE ore deposits and the wall rock is altered to fenite due to Na-metasomatism. The carbonate rocks are characterized by dolomite, magnetite, monazite, strontianite, apatite, columbite and fergusonite. Chemical compositions of this ore body show Fe of 21.1%, REE of 2.4%, SrCO3 of 1.8%, Nb7O5 of 0.12% and P of 2.9%. Mineral assemblages of mineralized zone, geochemical characteristics, fenite development, ore mineral texture, and stable isotope data indicate that mineralized carbonate rock represents typical characteristics of late differentiation stage of ferrocarbonatite.
