1211 by transforming suitable waste rocks into agricultural inputs. Rock powders produced by crushing and milling silicate rocks can act as multi-nutrient amendments, soil remineralizers and conditioners, supplying K, Ca, Mg and trace elements while improving soil chemical conditions, especially in acidic systems where base cation inputs alleviate Al toxicity and increase base saturation (van Straaten, 2006). Recent studies with basaltic rock powders report increases in soil pH and exchangeable bases and, in some cases, improved crop performance, reinforcing the potential of mafic quarry by-products as low-cost, regional nutrient sources (Luchese et al., 2023; Richardson et al., 2024; Theodoro et al., 2021; Zuffo et al., 2022). In Brazil, Law 12,890/2013 established the legal framework for the producing and commercializing these materials as soil remineralizers, defining them as mineral inputs obtained by mechanical size reduction and classification that improve soil fertility by supplying macro- and micronutrients and by enhancing physical, physicochemical, or biological properties. Under this legislation, soil remineralizers are defined as “mineral materials processed by mechanical size reduction and classification that improve soil fertility by supplying macro and micronutrients and enhancing physical, physicochemical, or biological properties.” To ensure the quality and safe application of these materials, Normative Instruction No. 5 (MAPA, March 10, 2016) specifies the required standards for chemical composition (CaO + MgO + K2O > 9%; K2O > 1% and maximum thresholds for potentially toxic elements (As <15 ppm, Cd < 10 ppm, Hg < 0.1 ppm, Pb < 200 ppm), mineralogy (quartz < 25 vol%) and grain size distribution (powder 100% < 2 mm, 80% < 0.84 mm, 50% < 0,3 mm; filler 100% < 0,3 mm). These criteria provide a regulatory foundation that guides the evaluation and certification of soil remineralizers for agricultural use. Beyond agronomic benefits, finely ground mafic rocks have gained prominence in climatemitigation strategies via Enhanced Rock Weathering (ERW). ERW accelerates the natural weathering of Ca- and Mg-bearing minerals, increasing alkalinity (bicarbonate formation) and enabling durable CO₂ removal while potentially delivering co-benefits for soil fertility (Hartmann et al., 2013; Beerling et al., 2020). This dual function strengthens the rationale for converting suitable mining waste rock into certified remineralizers. 2. GEOLOGICAL CONTEXT In the Serra Norte mines (N4 and N5), basalts, diabase dikes, and gabbros—collectively classified as mafic rocks—record multiple magmatic events associated with the geological evolution of the Carajás Mineral Province (CMP). These igneous units occur either as volcanic flows interlayered at the base (Parauapebas Formation) and top (Igarapé Cigarra Formation) of the banded iron formation, or as younger intrusive bodies represented by diabase and gabbro dikes and sills that cut the supracrustal sequence. Mineralogical analyses reveal that the volcanic rocks underwent extensive post-emplacement modification, resulting in the partial to complete replacement of their primary mineral assemblages. The abundant biotite, chlorite, and potassium feldspar indicate pervasive post-magmatic hydrothermal alteration, which reequilibrated the original mafic mineralogy under variable physicochemical conditions. This alteration is consistent with regional hydrothermal systems widely documented in Carajás and linked to the circulation of heated fluids during successive tectono-magmatic episodes. Fluid–rock interaction— facilitated by fractures, faults, and shear zones—promoted recrystallization and mineral replacement, generating alteration patterns of variable intensity dominated by potassic associations. The N4 Mine is subdivided into N4WN, N4W, N4WC, N4WS, N4EN, and N4E, distributed along the central eastern portion of the N4 plateau (Figure 1). This extensive plateau comprises rocks of the Parauapebas, Carajás, and Igarapé Cigarra Formations, arranged in tabular bodies that predominantly dip westward, forming a normal stratigraphic stacking. Prior to mining, the plateau was naturally divided into eastern and western sectors by a drainage channel separating the two main banded iron formation bodies. The eastern block is elongated N–S (8.5 × 1 km), whereas the western block is more regular (4 × 2 km), both ranging from 650 to 750 m in elevation. Geologically, N4 encompasses Archean and Proterozoic units dominated by iron-formation sequences affected by widespread hydrothermal alteration. Terrigenous sediments of the Águas Claras Formation overlie the BIFs, while younger arkosic deposits of the Gorotire Formation occur along normal faults that define a graben structure in the southern portion of the plateau (Nogueira, 1995; Azevedo et al., 2018). Across the plateau, the Parauapebas, Carajás, and Igarapé Cigarra Formations collectively define
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