Abstract

Fractals have been applied to vein systems to assess whether they have an organized and systematic structure. Understanding vein systematics allows realistic interpolation and extrapolation from available data by accurate prediction of the numbers and sizes of veins within a target volume. Vein geometries were measured from the Guanajuato epithermal Ag-Au field (Mexico) with vein attributes ranging from the millimetre to metre scale. Ores occur as mineralized quartz-calcite veins and stockworks in Tertiary sedimentary, volcanic and acid intrusive rocks. Mineralization is controlled by north-northeast-south-southwest regional extension. 1D sampling was found to be the most objective and effective way to compare the different data sets. Vein thickness distributions indicate an underlying power-law, with the scaling exponent varying between −0.66 and −0.88 over two orders of magnitude. When combined, the data maintain the same relationship over four orders of magnitude and are characterized by a slope of −0.75. Outcrop data, however, display higher densities within the stockwork. The agreement in scaling exponents between the various data sets suggests that they belong to the same overall structure and are most likely related to the same growth process.