| Popis: |
The modeling and correlation analysis of geophysical and geochemical data to evaluate the 3D distribution and control of ore grades are not usual procedures in mineral exploration of Au and basic metals. This paper aims to show the results of such modeling and correlation analysis. The method was developed for Volta Grande Prospect (Lavras do Sul, RS, Brazil). Volta Grande Prospect is composed by a series of Au-sulphide-quartz lode veins structurally controlled by radial fractures developed during Lavras do Sul Intrusive Complex. The lode veins show varying degrees of lateral hydrothermal alteration, and also display telescoping mesothermal to epithermal mineral assemblages. The lode veins are emplaced in intrusive granites and also in volcanic and volcano-sedimentary rocks of Hilario Formation. The geostatistical analysis showed the superposition of hydrothermally altered structures in some areas, while 3D kriging modeling revealed the geometry, and also the lithological and structural control of the conductive bodies. The correlation analysis between geophysical and geochemical data revealed the telescoping of different mineralization pulses, each one with different metallic load. The correlation analysis results are in accordance with hydrothermal alteration superposition as seen in field investigations. Therefore, the use of geophysical methods for grade control in sulphide-rich quartz-lode veins is a concrete possibility, since one have an adequate spatial resolution of geophysical surveys. |
