GEOLOGICAL AND GEOCHEMICAL INVESTIGATIONS
OF THE COPPER-ZINC DEPOSIT AT DUPAX, NUEVA VIZCAYA

RUDY C. OBlAL

 

 

 

ABSTRACT


The copper-zinc deposit is disposed in an area underlain chiefly by sedimentary rocks with intercalated volcanic rocks which are invaded by dikes and sills of basic to intermediate composition. The deposit occurs as massive sulphide replacement bodies in agglomerate and sulphide disseminations in silicified elastic sedimentary rocks. Major structures strike northwest and appear to conform with the trend of the zones of mineralization. The principal ore minerals are sphalerite, chalcopyrite, tennantite (?) and secondary covellite. The best grade ore exposed in the area, as reported by Lepanto Consolidated Mining Co., contains an average of 27.87% zinc and 2.62% copper with subordinate amounts of gold and silver.

Stream sediment and soil samples were collected and analyzed for copper and zinc by rapid colorimetric procedures. Anomalous stream sediments near sub-outcrop ping ore attain a maximum of 750 ppm copper and 780 zinc, Normal combined copper and zinc content ranges from 25 to 115 ppm. Copper and zinc in the weathering profiles increase with depth both in the unmineralized and mineralized outcrops. The rectilinear soil sampling revealed anomalies disposed along a general north-south direction with metal highs mostly related to mineralized exposures. Peak values reach 500-800 ppm copper and 350 ppm zinc, compared with normal contents ranging from 25 to 100 ppm copper and from 0 to 50 ppm zinc. These geochemical results tend to show that a commercially important orebody may occur beneath the 500-800 ppm copper ground or slightly upslope.

 

 

 

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