GEOCHEMICAL MAPPING OF IRON QUADRANGLE REGION BY ACTIVE STREAM SEDIMENTS, STATE OF MINAS GERAIS, BRAZIL

  • João Henrique Larizzatti CPRM - Geological Survey of Brazil
  • Eduardo Duarte Marques CPRM - Geological Survey of Brazil
  • Francisco Valdir Silveira CPRM - Geological Survey of Brazil

Abstract

The geochemical survey of Iron Quadrangle was performed by the Geological Survey of Brazil - CPRM involving geochemical data from the area between 42o30´W and 45oWand 19o30´S and 21oS, totalling 45.000 km2. Active stream sediment was analyzed. Fine fractions (< 80# or 0.175 mm) were pulverized to –150# fraction (~ 0.100 mm), digested by hot acqua regia and analyzed for 53 elements by ICPMS. Maps of raw and manipulated data (element concentrations and multi-elemental scores) were made. Stream sediment (< 80# fraction) is an effective sampling medium for regional geochemical surveys. Geochemical structures, lithological units and mineralization processes were recognized with the sample density of 1 sample per 12 km2. Sample density has a key role in the quality of the geochemical maps produced. Caution must be taken when interpreting the results because of its nature; these data do not necessarily pinpoint specific geochemical anomalies or single ore deposits. The interpretation of stream sediment samples is not straightforward and must take into account secondary processes involved in the evolution of sampling media. These data may be used in mineral exploration to delineate favorable targets for more detailed studies. Mineral deposits often occur in geochemical provinces characterized by elevated concentration of elements of economic interest and pathfinder elements. Ore deposits tend to cluster along specific stratigraphic units and/or structural trends over large areas. These geochemical data can be used in environmental studies, support decision makers in the definition of public policies and in the management of sustainable land use.

Author Biographies

João Henrique Larizzatti, CPRM - Geological Survey of Brazil
Department of Mineral Resources
Eduardo Duarte Marques, CPRM - Geological Survey of Brazil
Geochemistry Division
Francisco Valdir Silveira, CPRM - Geological Survey of Brazil
Department of Mineral Resources
Published
22-12-2018