LOW-DENSITY GEOCHEMICAL SURVEY IN SUB-CELL FROM STATE OF SÃO PAULO, BRAZIL

The São Paulo State was subdivided into square cells of 160 x 160 km based on the global geochemical reference network. One sub-cell (80 x 80 km) was chosen for this study, containing geological diversity and many conservation areas, in SE quadrant of S15W32 cell. Cartographic documents were compiled in the region where all small (<100km²) and large basins (1000-6000km²) were delimited. In these basins, the low-density geochemical survey is being done from the collection and geochemical analysis of samples of stream sediments (<0.150 mm), residual soils (A and C horizons, <2mm), and alluvial sediments - overbank and floodplain (top and base, <2mm and <0.150mm), and natural radionuclides (²³⁴U, ²³²Th and ⁴⁰K) in each site. The analytical data obtained, together with previously existing geochemical data, will be used for establishment of natural environmental quality. Geochemical analysis were performed with different protocols, using total (4-acid) and partial (USEPA 3050B) digestions, to provide geochemical data useful for a range of applications. The results will be compared with reference values established by national agencies throughout the world for various media (CETESB and USEPA) and provide geochemical data for mineral exploration and land use. This work was supported by FAPESP and CNPq, Brazil.