Metallogeny and applied exploration bedrock geochemistry (lithogeochemistry) of the Scheelite deposits of the Northeastern Brazil tungsten district, Brazil. (Volume 1: Text. Volume 2: Maps)

Exploration bedrock geochemistry (lithogeochemistry) was applied at regional, local, and mine scales for the recognition and definition of mineralized and anomalous areas, and to distinguish dispersion halos. Regional coarse-mesh sampling at 25 sq km centers 'found' all major mines and principal prospects using objective cost effective computer processing and mapping of data. Similar treatment given to data from principal mining concessions and prospects with outcropping and buried scheelite mineralization permitted recognition of outcropping mineralization at a distance of approximately 500 m. Ancillary anomalous areas relating to the leakage of hydrothermal solutions through fractures were related to buried mineralization at a depth of about 200 m. Primary dispersion halos for Cu, Mo, W, Be, F from conformable ores were recognized. A proposed volcanic-related primary mineralization model is based on the introduction of tungsten and other trace elements into the terrigenous protoliths by exhalative volcanic-related fumarole processes (leaching and/or juvinile mineralization) at the seafloor sediment interface.