Geochemistry of the Lower Protezoroic Granulite-Facies Grant Syenite Gneiss, Barra Velha, Santa Catarina State, Southern Brazil.

Abstract

A syenite body was discovered and studied in the Santa Catarina Granulitic Complex, close to the beaches of Grant and Barra Velha. The quarry, located on km·91 of BR-101 highway, was sampled for geochemical whole rock studies and also of its individual minerals. The syenite body is in structural and metamorphic equilibrium with the containing hypersthene-bearing tonalitic and basaltic granulites. Major, trace and rare-earth elements analyses on rock samples indicate syenitic to quartz dioritic compositions, saturated in alumina and silica. They have high contents of K, Na, Sr and Ba and low contents of Zr and Ti. Total REE is high in chondrite-normalized paterns and indicates strong fractionation of the light REE, similar to those for the Itiúba Syenite from Bahia State and for the Linden Syenite from Minnesota, USA. Overall geochemistry, on the other hand, is remarkably similar to the Archean Cléricy Pluton from Canada. The REE are strongly concentrated in allanite, clinopyroxene and sphene strongly. A Sm-Nd mineral isochron indicates metamorphic crystallization at ca. 2.2 Ga. The syenite is depleted in HFSE, and this may indicated a subduction-zone tectonic environment of generation of the magma. The foregoing results are based on 12 whole rock chemical analyses for major and some trace elements, three whole rock REE analyses, two electron microprobe analyses on each of seven minerals and Sm/Nd isotopic determinations on five minerals.

Zircon U-Pb geochronology and Hf isotopes of the Luís Alves Terrane: Archean to Paleoproterozoic evolution and Neoproterozoic overprint

“…This is in accordance with the fact that titanite in metabasic rocks is more stable in amphibolite facies than in granulite facies, where it is usually substituted by rutile or ilmenite (Frost et al 2001;Kohn 2017). This interpretation is coherent with the geochronological evolution suggested for the rest of the dataset, but challenges previous mineralogical and geochemical observations that assumed a magmatic origin for titanite in syenitic rocks of the LAT (Hartmann et al 1998).…”

“…The LAT (Hartmann et al 1979(Hartmann et al , 1998(Hartmann et al , 2000Basei et al 1992Basei et al ,1998aBasei et al , 2009bSiga Jr. 1995;Harara et al 2002Harara et al , 2003Passarelli et al 2018) consists of an Paleoproterozoic association with Archean protholiths, which in the Neoproterozoic was intruded by granites and locally covered by metavolcano-sedimentary basins. The basement units are grouped into the Santa Catarina Granulitic Complex (SCGC), predominantly a migmatitic-granitic-gneissic association with TTG signatures, while subordinately mafic and metasedimentary units also occur.…”

“…Available U-Pb, Rb-Sr, Sm-Nd and K-Ar geochronological data (Hartmann et al 1979(Hartmann et al , 1998(Hartmann et al , 2000Girardi et al 1974;Basei 1985;Basei et al 1998aBasei et al , 1999Basei et al , 2000Basei et al , 2009Siga Jr 1995;Harara 2001;Sato et al 2008) indicate an Archean to Paleoproterozoic evolution of the basement of the LAT with tectonic stabilization at the end of the Paleoproterozoic. However, most existing radiometric zircon ages were obtained by TIMS analyses and might partly result from mixed age populations.…”

Petrography and detrital zircon U-Pb geochronology of sedimentary rocks of the Campo Alegre Basin, Southern Brazil: implications for Gondwana assembly

“…35 Siga Jr. (1995), Basei et al (1998bBasei et al ( , 2009 Mantle/crust differentiate Addition of mantle-derived material to the crust Sm-Nd T DM 2.40-2. 30 Siga Jr. (1995), Hartmann et al (1998) Amphibolite-facies event Felsic granulite U-Pb in zircon (SHRIMP) 2. 48 Siga Jr. (1995), Harara (2001) Magmatism Intrusion of igneous rocks Rb-Sr WR isochrons 2.60 Basei (1985), Harara (2001) Granulite-facies event middle crust felsic granulite U-Pb in zircon (SHRIMP) 2.68 Hartmann et al (1979Hartmann et al ( , 2000 Magmatism TTG igneous activity U-Pb in zircon (SHRIMP), Rb-Sr WR isochrons 2.…”

Geologia do Terreno Paranaguá

“…O reconhecimento em campo das rochas gnáissico-granulíticas nas regiões de Morretes -PR, Serra Negra -PR e Itatins -SP (Microplaca Luis Alves setentrional), é dificultado em muitos setores devido a diferenças significativas nos aspectos composicionais e texturais, quando comparadas com as rochas da Microplaca Luis Alves meridional. sugere que esses terrenos representam um segmento da Microplaca Luis Alves "plissado" Em termos geocronológicos destacam-se os trabalhos de Girardi et al (1974), Hartmann et al (1979Hartmann et al ( , 1994Hartmann et al ( , 2000, Kaul e Teixeira (1982), Basei (1985), Basei e Teixeira (1987), Mantovani et al (1989), Machiavelli et al (1993), Siga Junior et al (1994a, 1994b, Siga , Basei et al (1998), Harara (2001) e Harara et al (2002, 2003 . No mesmo período ocorre expressivo vulcanismo no âmbito da Microplaca Luis Alves, associado a evolução das bacias de Campo Alegre, Guaratubinha e Corupá.…”