THE DAIRI ZINC-LEAD PROJECT, NORTH SUMATRA, INDONESIA
Discovery to Feasibility
Manager International Exploration, Herald Resources Ltd. 50 Colin St, West Perth WA 6005
Key words: sediment hosted massive sulphides; “Sedex” zinc-lead deposits; “MVT” zinc-lead deposits; Sumatran Fault System.
Sediment hosted, massive sulphidic, zinc-lead mineralisation was first identified by Herald Resources Ltd in the Sopokomil district of Dairi Regency, North Sumatra, during preliminary reconnaissance and stream sediment sampling in late 1997, prior to granting of a Generation VII Contract of Work. Staged exploration for stratiform, possibly sedimentary exhalative (“sedex”) style mineralisation resulted in the tracing over about 5km of strike on the NE flank of the complex Sopokomil Dome a series of horizons and lenses, referred to as the “Julu Sedex Zone” (JSZ) in laminated carbonaceous shale and dolomitic siltstones, of the designated Julu Member,.
Extensive, but lower grade base metal and silver rich mineralisation in several styles, in particular the designated “Jehe Mississippi Valley type”, has been discovered in the massive dolostone footwall units which form the core of the Sopokomil Dome. The local lithostratigraphic sequence is part of the poorly constrained Permo-Carboniferous age Tapanuli Group, the basal rocks