MAPPING ALTERATION ZONES TO LOCATE A POSSIBLE IRON OXIDE COPPER GOLD-TYPE OREBODY

Recent mapping in the Plumas Copper Belt suggests the potential for a previously unmapped copper ore body at depth. The field area is located at the north end of the Plumas Copper Belt in the Lights Creek District of Northern California. The Lights Creek district is home to two past producing copper mines, the Engles Mine and the Superior Mine. Between 1916 and 1930 the Engles Mine and Superior Mine reported joint production of 161.5 million tons of copper from 4.5 tons of copper ore with an average feed grade of 2.2% copper. Broad scale and select detailed mapping of a 10 km long by 8 km wide portion of the Lights Creek Copper District has identified a potential target ore body at depth. Detailed field mapping, thin section analyses, and regional historical records are used to understand the magnitude and nature of the host rock and copper deposits in the area. The area is dominated by two lithologies, the roof pendant metavolcanic rocks that overlie an intrusive quartz monzonite. Along with mapping, thin section samples have been used to identify the localized zones of alteration, which are good indicators of hydrothermal activity in the area. Hydrothermal alteration of the both the metavolcanic rocks and the quartz monzonite are commonly associated with copper deposition in the Lights Creek district. Our interpretation is that the Lights Creek District is an Iron Oxide Copper Gold-type deposit (IOCG). There is an abundance of hematite and magnetite in the system along with chloritization of the host rock, consistent with typical IOCG mineral zones. Ongoing work will produce a geologic map showing the lithologic variation, alteration zones and structural orientations of copper veins and other ore minerals to constrain the larger ore body target at depth.