Uraninite-Bearing Leucosomes from Migmatites of Chhotanagpur Granite Gneiss Complex, Karke Area, Garhwa District, Jharkhand, India

Uraninite, brannerite and secondary uranium minerals have been identified by petrographical studies of the leucosome of migmatites from Karke area, Garhwa district, Jharkhand (Figure 1). Secondary uranium minerals show fine flaky nature, anomalous interference colours and medium to high density alpha tracks on CN film. The host of uranium minerals is lensoidal in nature and occurs within the melanosome part of migmatitic band in Chhotanagpur Granite Gneiss Complex (CGGC)1. The width of migmatite varies from ~10 m to ~100 m, especially in Karke area. The migmatitic bands are flanked by pink granitoide occurring as linear body along the northern periphery. These are partially granitized metasediments and are the part of migmatites. These migmatites are hosted in biotite granite gneiss country with general trend of N65°W to S65°E, in this part of CGGC (Figure 1). A total of nine lenses of radioactive leucosome have been traced within a zone of 1000 m × 30 m trending NW–SE (Figure 2). The radioelemental distribution in these rocks is given in Table 1.