Petrografia, química mineral, geoquímica e geocronologia dos stocks Santa Maria, Monte Pedral, Bom Jardim, Boa Esperança e Niterói

Abstract

The Serra do Catu Intrusive Suite occur in the northern region of the Sergipano Orogenic System, in the Poço Redondo and Canindé domains. In this region there are five stocks with diverse compositions: Monte Pedral (alkali-feldspar syenite and alkalifeldspar quartz syenite); Boa Esperança (quartz alkali-feldspar syenite and alkalifeldspar granite); Santa Maria (granite); Niterói (monzogranite, monzonite quartz and monzodiorite quartz); Bom Jardim (granite, monzonite quartz, granodiorite, quartz monzodiorite and diorite). The geochronological data of the Santa Maria Stock in UPbSHRIMP, show an age of crystallization of 611 ± 4 Ma. The porphyritic texture, multiple zonations in feldspar phenocrysts, particularly in orthoclase and microcline, associated to the abundance of mafic enclaves are characteristics that distinguish these rocks from the other intrusions of the Canindé Domain. The Monte Pedral and Boa Esperança stocks are hypersolvus and the others (Bom Jardim, Niterói and Santa Maria) correspond to a subsolvus plutonism. The brown mica corresponds to biotite and phlogopite, presenting calcium-alkaline affinity. Mg-hornblende and Tschermakita are the primary amphiboles in these rocks and crystallized under oxidizing conditions and depths ranging from 12 km (3 Kbar) to 26 km (7 Kbar). Geochemical data show that these rocks have shoshonite affinity, enrichment in light ETRs relative to heavy and negative anomalies in Ta, Nb, P, Sr and Eu. These rocks crystallized at a maximum temperature of 864 °C.