Mineral weathering in acid saprolites from subtropical, southern Brazil

Scientia Agricola

Celso Augusto Clemente¹  Antonio Carlos De Azevedo¹ 

[1] ,USP ESALQ Depto. de Ciência do SoloPiracicaba SP ,Brasil

关键词: Paraná Basin;    riodacites;    plagioclases;    pyroxenes;    magnetites;    Bacia do Paraná;    riodacitos;    pagioclasios;    piroxênios;    magnetitas;   

DOI  :  10.1590/S0103-90162007000600007

来源: SciELO

【 摘 要 】

Because weathering of minerals releases chemical elements into the biogeochemical cycle, characterization of their weathering products helps to better model groundwater quality, formation of secondary minerals and nutrient flux through the trophic chain. Based on microscopic and elemental analyses, weathering of riodacite from Serra Geral formation was characterized and weathering paths proposed. Three weathering paths of plagioclase phenocrystals were identified: plagioclase to gibbsite (Pg1); plagioclase to gels and gibbsite (Pg2); and plagioclase to gels, gibbsite and kaolinite (Pg3). Pyroxenes weathered to smectite and goethite (Py1), or to goethite and gibbsite (Py2), and magnetite weathered directly into iron oxides. Rock matrix comprises 90% of rock volume, and weathered to kaolinite and gibbsite, which explains why these minerals were the most abundant in the weathering products of these saprolites.

【 授权许可】

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