Nature and Mode of Occurrences of the Gold Mineralisation in and around Sindauri-Ghanshyampur Area of North Singhbhum Mobile Belt, Singhbhum Crustal Province, Eastern India

ABSTRACT Palaeo- to Mesoproterozoic North Singhbhum Mobile Belt (NSMB) within the North Singhbhum Crustal Province (NSCP) is a metallogenic province, well known for many gold occurrences within the phyllite intercalated with quartzite unit of the Singhbhum Group. The present study has been conducted in and around the Sindauri-Ghanshyampur area, within the Singhbhum Group of rocks, lying along the northern boundary of the Dalma volcano-sedimentary belt of NSMB. The gold mineralisation within the Sindauri-Ghanshyampur area is limited to the quartz veins and veinlets intruded into the phyllite and intercalated quartzite along the east-northeast trending Lungtu-Parasi-Sindauri shear zone. The anomalous gold values within the area are reported from quartz/carbonate veins and veinlets, which are parallel to the S2 foliation along the Lungtu-Parasi-Sindauri shear zone. Gold occurs in association with arsenopyrite, pyrrhotite and pyrites. However, at places, it also occurs as isolated specks. The shearing within the Sindauri-Ghanshyampur area is evident by the mylonitisation within the tuffaceous phyllite intercalated with the quartzite. Shear zones act as a conduit for hydrothermal fluid migration. The present study is the first report of gold deposits within the Sindauri-Ghanshyampur area in Ranchi District, Jharkhand, explored by the Geological Survey of India (GSI). Based on the gold assay results of core samples of boreholes SEB-6 to 10, a total of 1.147 million tons of Inferred Mineral Resource with an average grade of 1.030 ppm were calculated. From borehole SEB-12, the total estimated resource for Au is 0.767 million tonnes with an average grade of 0.81 g/t. The nature and the mode of occurrence of gold mineralisation within the Sindauri area indicate that the gold mineralisation is of orogenic type. Gold was deposited by the hydrothermal fluid to form an epigenetic gold deposit along the S2 foliation and shear planes.