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

摘要

At Jacupiranga (Brazil) the latest manifestations of C3 carbonatite are veins and impregnations of sovite 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 (H20±C02±NaCl±KCl±NaHC03) with 17-50 vol.% of gas bubble, (ii) multi-phase melt inclusions of two types, carbonate-H20 rich and silicate-carbonate-H20 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.