Petrogênese do magmatismo shoshonítico da suíte intrusiva Serra do Catu, domínios Canindé e Poço Redondo, sistema orogênico Sergipano

Abstract

The Santa Maria (SSM; 611 Ma), Monte Pedral (SMP), Bom Jardim (SBJ), Niterói (SN) stocks and Batholith Curituba (BC; 624 Ma) are intrusions that belong to the Serra do Catu Intrusive Suite and occur in the Poço Redondo and Canindé domains, Sergipano Orogenic System. These stocks and batholith are formed by quartz monzonite, monzogranite, quartz syenite, syenogranite and alkali-feldspar syenite. This magmatism is metaluminous, with the most evolved rocks being weakly peraluminous, magnesian to ferroan and showing magmatic affinity with shoshonitic suites. Rock chemistry exhibits subparallel patterns in multielemental diagrams and presents valleys in Ta-Nb-Ti, implying magma originating from the mantle and modified by fluids from subduction processes. The contents of Rb, Y and Nb are like synchronous to post-collisional magmas generated in volcanic arc environments. These rocks have calcic magmatic amphibole, which corresponds to magnesium-hornblende, edenite, magnesium-hastingsite, hastingsite and tschermakite, while the post-magmatic consists of actinolite. The amphiboles of these plutons have chemical compositions like crystals formed in alkaline and subalkaline magmas, a typical characteristic of shoshonitic series magmas. It was inferred that the amphibole primary crystals were formed from mantle magmas and mixed magmas (mantle + crustal). The studied bodies were placed under different temperature and pressure conditions: SM (808 ◦C; 470 MPa; 14.6 km), SN (801 ◦C; 550 MPa; 17 km), BC (879 ◦C; 740 MPa; 22.9 km), SBJ enclave (877 ◦C; 860 MPa; 26.6 km) and BC enclaves (912 ◦C; 970 MPa; 30 km). The isotopic data of Nd and Hf reveal that the protolith of these rocks is derived from melting of the enriched mantle and that there was a crustal contribution during the evolution of magma.