Late veins of C3 carbonatite intrusion from Jacupiranga complex (Southern Brazil): fluid and melt inclusions and mineralogy.

At Jacupiranga (Brazil) the latest manifestations of C3 carbonatite are veins and impregnations of sövite composition containing carbonates, Fe-oxides, apatite, phlogopite, olivine, clinohumite, pyrochlore, zirconolite. Apatite contains fluid inclusions l.s. of two types: (i) two-phase fluid inclusions of complex composition (HO±CO±NaCl±KCl±NaHCO) with 17-50 vol.% of gas bubble, (ii) multi-phase melt inclusions of two types, carbonate-HO rich and silicate-carbonate-HO rich with very high homogenization temperatures up to 584°C and up to 1194°C, respectively. The coeval origin of fluid and melt inclusions allows to calculate the trapping pressures which indicate approximate depths of 30 to 60 km for the origin of the veins. Carbonatite veins contain Ba-poor tetra-ferriphlogopite of extreme composition which extends the compositional trend of the micas of Jacupiranga. The occurrence of zirconolite, Nb-rich pyrochlore and Ta-rich U-pyrochlore is mutually exclusive and related, probably, to the variation of fluorine content in the magmatic fluids. [ABSTRACT FROM AUTHOR]