Produção Nacional
Petrography, Geochemistry and Geological/Geochemical Modeling of a Portion of the Phosphorus-Uraniferous Mandacarú Target, Irauçuba-Ceará, Brazil
2022; RELX Group (Netherlands); Linguagem: Inglês
10.2139/ssrn.4277974
ISSN1556-5068
AutoresAlan Dantas Cardoso, Luiz Alberto Vedana, Joaquim Daniel de Liz, Cristine Lenz,
Tópico(s)Geochemistry and Geologic Mapping
ResumoThe Mandacarú target (Irauçuba-CE) occurs in the Phosphorus-Uraniferous Province, in the Ceará Central Domain, Borborema Province, together with the Serrotes Baixos, Taperuaba and Itataia targets. The host rocks are medium to high grade paragneisses, related to the Neoproterozoic Santa Quitéria magmatic arc association of rocks. The studied borehole samples exhibit a high amphibolite facies mineral assemblage, with massive hydrothermal minerals. Sodic metasomatism is evidenced by the chloritization of biotite, albitization of feldspar, riebeckitization of amphiboles and hematitization, in addition to subsequent sericitization and saussoritization of albite. With whole rock geochemical data we identified 35 mineralized zones with thicknesses varying between 60 cm and 18 m, P2O5 values reaching 15.11% and U values of 8,380.39 ppm. Areas with a mineralized zone thicker than 10 m and a P2O5 and U content greater than or close to 10% and 1,000 ppm, respectively, stand out. The mineral chemistry showed that colophane, ore mineral is chemically a fluorine-apatite of amorphous nature, with P2O5 content between 36.46 and 42.18%, CaO between 50.56 and 56.69% and F between 1.23 and 2.22%. A mineral of SiO2 and UO3 was identified, ranging from 13.90 to 26.49% and 55.12 to 77.47%, respectively, and was classified as a coffinite. The geological/geochemical modeling of the area resulted in: 32.92% of phosphorus mineralizations material, 67.08% of sterile material. With regard to volume, 90.88% are composed of sterile rocks, while 9.12% are composed of mineralized rocks. The mineralizations are geographically concentrated in the central-eastern part of the studied area, in addition to being arranged close to the surfaces, which are positive points for a possible opening of an open pit mine. The Mandacarú target rocks have similarities with the Itataia Deposit rocks, since both are located in a similar geological/geographic context, where in both the mineralization is associated to albitization (sodic metasomatism). However, the higher P2O5 and U contents in the Itataia Deposit can be explained by better structural conditions for ore concentration, in addition to a possible low effectiveness of some mineralized phases of the Mandacarú target.
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