The parisite-(Ce) mineralization associated with the Fazenda Varela carbonatite (Correia Pinto, SC)

Tamara Reginatto Manfredi (1) , Artur C. Bastos Neto (2) , Vitor P. Pereira (2) , Luc Barbanson (3) , Cristine Schuck (2)

1 Instituto de Geociências
2 Instituto de Geociências
3 ISTO - Institut des Sciences de la Terre d'Orléans - UMR7327

The Fazenda Varela carbonatite is part of the Lages alkaline complex (Late Cretaceous). The car - bonatite occurs as abundant veins that cut the sandstones of the Rio Bonito Formation which are strongly brecciated and metasomatized. Petrography, geochemistry, X-ray diffraction, scanning electron microscopy and electron microprobe data allowed the identification and classification of REE fluorcarbonates. The car - bonatite is composed essentially by ankerite and Fe-dolomite and was strongly affected for tardi and post magmatic events. The hydrothermal fluids percolated through fractures and grain boundaries and formed hydrothermal domains composed of barite, apatite, quartz, calcite, Fe-dolomite, and parisite-(Ce). In these domains, parisite-(Ce) occurs as well-developed fibrous to fibroradiated crystals. Parisite-(Ce) also occurs in hydrothermal veins that cut the metasomatized host rock. The parisite-(Ce) crystals are heterogeneous, occur in syntaxial growth with synchysite-(Ce), and have excess of Ca and REE and F depletions in relation to an ideal composition. The parasite-(Ce) mineralization formed from a fluid with low F activity that interacted with the rock and leached preferentially the LREE, which were likely transported as chlorine complexes

Mots clés: Fe-carbonatite; parisite; synchysite; REE

Domaines: Minéralogie

Tamara Reginatto Manfredi, Artur C. Bastos Neto, Vitor P. Pereira, Luc Barbanson, Cristine Schuck. The parisite-(Ce) mineralization associated with the Fazenda Varela carbonatite (Correia Pinto, SC). Pesquisas em Geociências, 2013, 40 (3), pp.295-307. ⟨insu-00924154⟩