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Granitos peraluminosos intrusivos no Complexo Metamórfico Brusque: registro do magmatismo relacionado a colisão neoproterozóica no Terreno Tijucas, Itapema (SC)

2010; Sociedade Brasileira de Geologia; Volume: 40; Issue: 3 Linguagem: Inglês

10.25249/0375-7536.2010403303320

2177-4382

Ruy Paulo Philipp, Roberto Sacks de Campos,

Geological and Geochemical Analysis

Brusque Metamorphic Complex is one of the main units of the Tijucas terrane in Santa Catarina state. This complex, located in the Itapema region is constituted by metasedimentary association with subordinate presence of mafic and ultramafic metavolcanic rocks and peraluminous granites. The granites have tabular form from centimetric to metric thickness intruding metapelites, mafic and calc-silicate schists. These units are tectonically interposed and disposed to a low angle foliation from northeast-southwest direction. The granites are concordant with the S2 foliation and lie in according to axial surfaces of isoclinal F2 folds. The granite have a monzogranite composition with a K-feldspar, plagioclase and quartz, subordinates quantities of muscovite and tourmaline, with biotite, garnet, monazite, zircon, apatite and opaque minerals as accessories. The main structure is a magmatic banding of centimetric thickness alternating regular and continual levels from medium to coarse equigranular texture as well as pegmatitic texture levels. The banding is originated by successive fulfilling of fractures by granite injections. Geochemical studies characterize the granites as peraluminous magmatism related to high- K calc-alkaline series. The majors and traces elements patterns present values for the ratios LaN/YbN (1.34 to 4.66), K2O/Na2O (0.86 to 1.72), CaO/Na2O (0.11 to 0.44) and low values of Rb, Sr, Zr and RRE, are similar to peraluminous granites of other orogenic belts of Phanerozoic age. These type of granites are usually associated to rock generated by partial fusion of crustal sequences of pelitic composition with formation of a granulitic residue. Structural relations between the position of the granitic bodies and metamorphic evolution of the Brusque Metamorphic Complex associated to geochemical and geotectonic parameters are related to magmatism generator by anatexis connected to collisional event of the end of Brasiliano Cycle.