Geochemical prospecting for copper in the northern part of Yuma County, Arizona

Geochemical prospecting for copper has been carried out in two selected areas in the northern part of Yuma County, Arizona. These areas have a few old copper mines and some other zones of mineralization. The rocks of the area range in age from Precambrian to Quaternary and consist of complex gneiss, lava flows, schists, marble, sandstone, conglomerates and some intrusive dikes. A cold-extractible [sic] field method was used to study the relation between the copper content of stream sediments in washes and the geology, mineralization, and topography of the areas. A few total copper tests were also carried out. Another purpose of the thesis was to find how well the cold-extractible [sic] method of geochemical prospecting would work in the environment of this region. Because weathering has been mainly mechanical in nature, very little of the copper goes into solution and copper is mostly found in the fine fractions of the soil as particles of copper silicate and copper carbonate. The chemical results indicate that mineralization is associated with carbonate rocks. There is a strong relation between the copper dispersion and the rock types and structure of the local area that each wash cuts through. The cold-extractible [sic] method is as good as the total copper method in finding and tracing the copper dispersion patterns; the simplicity and the low cost of the cold-extractible [sic] method make it the best test to use in this type of area. This method of prospecting should be useful in similar areas where mineralization is close to the surface. Cold-extractible [sic] copper values for the area range from O ppm to 1200 ppm. Total copper values range from 250 ppm to 6400 ppm --Abstract, page ii