Stable (C, O, S) isotopes and whole-rock geochemistry of carbonatites from Alto Paranaíba Igneous Province - SE Brazil

GOMIDE, CAROLINA; BROD, J. A.; JUNQUEIRA-BROD, T. C.; PETRINOVIC, I. A.; SANTOS, A.; BARBOSA, S.R.; MANCINI, L.

Brazilian Journal of Geology

Sociedad Brasilera de Geología

Año: 2015 vol. 46

The present work investigates the relationship between whole-rockgeochemistry and stable isotope composition from carbonatites belonging to theTapira, Araxá, Salitre, Serra Negra, Catalão I and Catalão II alkaline-carbonatitecomplexes of the Alto Paranaiba Igneous Province (APIP), central Brazil andfrom the Jacupiranga Complex, of the Ponta Grossa Province, southeast Brazil.The APIP complexes are ultrapotassic, comprising bebedourites, phoscorites,nelsonites, and carbonatites, whereas Jacupiranga is a sodic complexcomposed of ijolite-series rocks, syenites, carbonatites and alkaline gabbrosThe geochemistry data, alied to mineralogical constraints allowed 30 us to classifie31 the carbonatites into 5 groups, and to devise a chemical index32 (BaO/(BaO+SrO)) to gauge the magmatic evolution of the studied carbonatites.33 The APIP carbonatites evolve from apatite-rich calciocarbonatites toward Ba-,34 Sr-, and REE-rich magnesiocarbonatites. This evolution is mostly driven by35 apatite, phlogopite, dolomite, and calcite fractionation and consequent36 enrichment in monazite, norsethite and strontianite.37 Stable isotope data show a wide diversity of petrogenetic processes in play at38 the APIP, relatively to the Jacupiranga Complex, which is interpreted as a result39 of the shallower intrusion levels of the APIP complexes. Such shallower40 emplacement, at low lithostatic pressure, allowed for a complex interplay of41 fractional crystallization, liquid immiscibility, degassing and interaction with42 hydrothermal and carbohydrothermal