BIF-hosted Fe deposits in Brazil

BIF-hosted
Fe deposits in Brazil
C. A. Rosière
Carajás
Urucum
Characteristics of BIF
Sequences
Paleoprot. BIFs
Archean BIFs
Neoprot. BIFs
Supergene
Mineralizing
Fluid Systems
Mineralogy and
Fabric
Rock and Mineral
Chemistry
Hypogene
Type I
Tectonic controlled
Large hydrothermal
alteration halo
Large fluid volumes
Complex reactions and
mineralogy
Carajás
Carajás SZ
Hydrothermal signature
in BIF and igneous rocks
Multiple mineralization
Complex mineralogy
Fe-mineralization of
volcanics
Role of granite
Incomplete scenario
São
Francisco
Craton
Quadrilátero
Ferrífero
Oxidized nature of the
BIF?
Rhyacian Flats and Ramps
Hydrothermal signature:
carbonatization and
oxidation.
Fe-mineralization and
veins in country rocks
Multiple mineralization
Complex mineralogy
Metamorphic fluids
Eisen Oxide
Veins
High-grade ore
from dolomitic
itabirite
Fe-Mobilization in the
Espinhaço SG
Type II
Oxidized nature of the BIF
Tectonic controlled
Inconspicuous hydrothermal
alteration halo
Large fluid volumes
Little reactivity
Solution precipitation reactions
Serra da Serpentina
Pressure Solution and
Residual Concentration
Type III
Magnetitites
Tectonic controlled?
Magmatic contact
Pegmatites
Complex reactions
and mineralogy
Fe-Skarn?
Guanhães
Piçarrão Baratinha
Neoproterozoic BIFs
and ironstones
Oxidized nature of the BIF
Type IV
Sedimentary/Tectonic (?)
controlled
Weak or no hydrothermal
alteration halo
Reduced fluid volumes
Little reactivity
Mainly Supergenic
Grupo Jacadigo
Fm. Nova Aurora