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Título

STRUCTURAL CONTROL AND METALLOGENIC MODEL FOR NEOPROTEROZOIC SEDIMENTARY PHOSPHATE DEPOSIT: INSIGHTS FROM MORRO VERDE MINE (PRATAPOLIS, MG) BRASILIA BELT MERIDIONAL

Texto do resumo

The Morro Verde Mine, situated in Pratápolis, Minas Gerais, plays a crucial role in extracting critical phosphate minerals, contributing to the production of phosphate fertilizers essential for global food production security. This mine occurs in a metasedimentary sequence composed of phyllite, phosphate siltstone and limestone covering the Archean-Paleoproterozoic basement of the São Francisco Craton and tectonically overlain by the Passos Nappe. The purpose of this work is to highlight the complex deformation history that controls the phosphate ore distribution, characterise and explain the ore grade control to finally emphasis an exploration model. This work involved field activities consisting macrostructural description of cross-sections along the mine benches, as well as the collection of orientation measures of deformational structures. Well selected area of the mine has been sampled to characterise petrogenesis and microstructural textures by thinsections. The data suggest that multiple NW-SE fault zones impacted and reworked the original sedimentary phosphate mineralization, leading to the formation of thick cataclasite bands categorized as fault zones. These zones consistently exhibit slickenside planes and served as pathways for hydrothermal fluids, which caused widespread metasomatism, involving the addition of silica and enrichment in P2O5. Metasomatism increased the hardness of cataclasites and associated limestones, which are both valuable targets for mining activities. Limestones involved into fault zone exhibit high degree of metasomatism, they act as sponges which absorb-retain silica and phosphate mobilized through fault zone. Additionally, it indicates that metasomatism results in the silicification and phosphate enrichment of these lithologies. Among all phosphate-bearing lithologies, cataclasite is the one that has the highest P2O5 variability, ranging from 03% to 36%. Such variability is correlated with the amount of phosphate-bearing rock involved in cataclasite genesis. Overall findings from this work offer valuable insights into the complex interaction between tectonic and hydrothermal processes in the region. Both of them control the spatial distribution and the ore percentage of the Morro Verde phosphate mineralization.

Palavras Chave

Phosphate; Structural geology; Cataclasite; Hydrothermalism.