1212 the main lithostratigraphic and structural domains. The Carajás Formation forms two distinct belts (N4W and N4E), separated by an east-verging thrust fault. N4W is characterized by a relatively simple homoclinal structure segmented by NW–SE dextral strike-slip faults, whereas N4E displays more complex patterns, including rotated banding and a J-shaped fold produced by drag along major shear zones. The Parauapebas Formation consists predominantly of Upper Proterozoic volcanic basalts originally composed of olivine, pyroxene and feldspars. These rocks underwent intense hydrothermal alteration and weathering, generating secondary mineral phases such as chlorite, zeolites, hematite and magnetite. The Carajás Formation—representing about 40% of the plateau—is the thickest and most continuous iron-formation unit, composed of hematite- and magnetite-rich BIFs locally referred to as jaspilites and strongly controlled by strike-slip deformation. The Igarapé Cigarra Formation crops out west of the Carajás Formation and includes extensive bimodal volcanic sequences interlayered with thin BIF lenses. Its basalts also record intense hydrothermal alteration marked by abundant chlorite, zeolites and clay minerals (Martins et al., 2017). Figure 1 – Geological map of the N4 deposit 3. MATERIALS AND METHODS A literature review of the Carajás Mineral Province, combined with an evaluation of regional geological mapping data, identified the most prospective volcanic units as the Parauapebas and Igarapé Cigarra Formations, as well as associated mafic dikes and sills. Within Vale’s geological modeling framework, metabasalts are classified as waste in iron-ore resource and reserve estimation. However, for dilution calculations, contact intervals between waste and banded iron formation in drill cores are recovered, logged, sampled, and submitted to chemical and/or mineralogical analyses. As a result, the company’s exploration database contains a robust set of analytical information for the targeted stratigraphic units. Based on the distribution of chemical parameters required by Brazilian regulations for registering
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