Geologia do Terreno Paranaguá

Abstract

The Paranaguá Terrane is composed of precambrian geological units distributed in a NE-SW elongated swath, about 250 km long and 30 km wide, in south-southeastern Brazil, within the States of São Paulo (Nothern Paranaguá Terrane), Paraná and Santa Catarina (Southern Paranaguá Terrane). This terrane is constituted mainly by an igneous complex, represented by the Morro Inglês, Rio do Poço and Canavieiras-Estrela suites. The country rocks of these l.s. granites are gnaissic and gnaissic-migmatitic rocks of the São Francisco do Sul Complex and metassedimentary rocks of the Rio das Cobras Sequence. Lithochemical signatures of the Morro Inglês Suite are compatible with arc magmatic-generated granitic rocks, with high-K to shoshonitic calc-alkaline character and relatively high contents of Ba, Nb, Zr, Rb, Sr, Th and K 2 O. This pattern resembles the one observed in sin-to late-collisional environments related to mature magmatic arcs, with sources modified by crustal contamination. The Canavieiras-Estrela Suite is composed of quartz-monzodiorites, leucogranites and monzogranites, with porphyritic and inequigranular rocks, with mafics represented by biotite ± anfibole. Comparativily, the Morro Inglês Suite rocks present higher values of K 2 O and smaller values of Na 2 O than the rocks of the Canavieiras-Estrela Suite. Both suites show important variations of Ba and Sr, high values of Rb and Zr, and medium-to-high values of Nb and Y. Two distinct rock units can be individualized in the Rio do Poço Suite, based on petrographical and lithogeochemical differences. The rapakivi sienogranites characteristics are compatible with metaluminous to marginally peraluminous type A granites. Such interpretation does not seem adequate for the two-mica leucogranites in this suite, which present a marginally peraluminous character, with HREE-depleted rocks, without an Eu negative anomaly. Petrographic and, mostly, structural data suggest that the Morro Inglês, Canavieiras-Estrela and Rio do Poço suites emplacement occurred during a late stage of the collisional event. U-Pb ages (zircon) of these suites are very close and does not allow a clear separation of them. A high concentration of ages between 600-580 Ma represent the main magmatic period of the Paranaguá Terrane. Although less frequent, older ages between 620-610 Ma were obtained in the three suites, suggesting the presence of a relatively early magmatism in this terrane's evolution. U-Pb ages (zircon) obtained in crystals borders, as well as in late leucogranitic veins, are distributed between 560-480 Ma. These ages must be related with important thermotectonic events of the Cambro-Ordovician Rio Doce Orogeny. The metassedimentary rocks of the Rio das Cobras Sequence occur as elongated strips, with little areal expression. In the southern portion of the Paranaguá Terrane, green schist (biotite zone) paragenesis are present (Serra da Prata -PR), while in the central and northern portions there are afibolite facies paragenesis up to granulite facies in association with kyanite-garne...

Arcabouço geofísico-estrutural da porção meridional do Cinturão Ribeira

“…Adaptado de Basei et al (1992), Siga Jr (1995, Portela Filho e Ferreira (2003), Cury (2009), Heilbron et al (2008). Terrenos tectônicos: 1 -Apiaí; 2 -Curitiba; 3 -Luis Alves; 4 -Paranaguá; 5 -Juiz de Fora.…”

“…Estruturas principais: ZCI -Zona de cisalhamento Itapirapuã; ZCMA -Zona de cisalhamento Morro Agudo; ZCL -Zona de cisalhamento Lancinha; SP -Sutura Piên. Transectas relizadas: A, B e C. com base em estudos geológicos envolvendo característi-cas litológicas, petrográficas, estruturais, geocronológicas e geoquímicas, além de dados gravimétricos (Basei et al 1992, Cury 2009). O Terreno Apiaí é constituído por sequências metavulcanossedimentares meso e neoproterozoicas, núcleos do embasamento paleoproterozoico e maciços graníticos neoproterozoicos, cuja associação compõe compartimentos tectônicos balizados por expressivas zonas de cisalhamento num contexto deformacional transpressivo (Fiori 1990, 1992, Campanha & Sadowski 1999, Cury 2009, Heilbron et al 2008, Siga Jr. 2010.…”

“…2.0 Ga), sobrepostos por uma sucessão metassedimentar de margem passiva representada pelos metassedimentos das sequências Capiru, Setuva e Turvo-Cajati, afetadas por um episódio metamórfico a 600 Ma (Heilbron et al 2008, Cury 2009). …”

“…Ocorrem subordinadamente rochas migmatíticas e graníticas, básicas e ultrabásicas, além de gnaisses calciossilicáticos, kinzigitos, formações ferríferas e quartzitos (Cury 2009). …”

Interpretação qualiná, sul do Brasiltativa e semiquantitativa dos dados aeromagnéticos sobre a zona de cisalhamento lancinha, porção meridional do cinturão ribeira no estado do Para

“…al. (1992), Siga Junior et al (1995, Portela Filho e Ferreira (200), Heilbron et al (2008), Cury (2009)…”