Graphitization of carbonaceous material in Paleozoic rocks in the Yaguki area, Abukuma Mountains, Northeast Japan

Paleozoic rocks in the Yaguki area were thermally metamorphosed and mineralized by the Cretaceous granodiorite. Graphitization of carbonaceous material in pelitic and carbonate rocks was investigated by X-ray powder diffraction method. Lc(002) values of carbonaceous material in pelitic rocks increase toward the granodiorite pluton, and reaches 800 Å near the contact with granodiorite. The ratio between La(110) and Lc(002) isapproximately 1.7 below Lc(002) of 600A and increases markedly above 600 Å. Lattice dimension 4. of carbonaceos material decrease with increasing Lc(002), and reaches 3.35A at Lc(002) value of 300 Å. Carbonaceous materials in limestone near skarn orebodies have lower Lc(002) values than those of pelitic rocks at the same distance from granodiorite pluton. The fact indicates that the graphitization of carbonaceous material was obstructed by the fluid that formed the skarn ore deposit