The Red Dog lead-zinc deposit in the Brooks Range of Alaska is the single largest zinc deposit in the world and presently supplies 10% of the world's zinc. The ores are hosted in black shales of the Kuna formation of Carboniferous age. The ore deposit is classically described as Sedex or shale-hosted base metal deposit. This presentation will describe the discovery, geological setting, geochemistry and new insights into the genesis of this giant deposit.

The ores replaced carbonate turbidites and baritic black shales. The sulfides are dominantly sphalerite with lesser galena. The ore reserves are in excess of 150 million tons with sulfide grades greater than 20%.

Fluid inclusion studies show that the ore forming fluids were basinal brines similar to MVT deposits. The deposit is best described as syndiagenetic to epigenetic replacement ores. In many ways this deposit does not fit the classical Sedex model.