Control of Sulphide Mineralization at Bhotang Sulphide Deposit (Sikkim)

The copper-zinc-lead sulphide mineralization of Bhotang is confined to the Dalling Group of eastern Himalaya. Confinement of the sulphide mineralization within a litho-unit, and its strong preference to planar and linear fabrics suggests litho-structural control. The dimensional variability and geometrical shape and size of the ore body is the result of later deformational influences. Pinch and swell structure in the ore lenses is common. The arc body shows pronounced zoning. Localization of sphalerile, galena and chalcopyrite indicates differential mobilization in response to repeated deformation and metamorphism under varying temperature conditions. The mode of occurrence of the polymetallic sulphide bodies, their attitudes, dimensional significance and control are described.