Lithogeochemistry of granitoids in the São Sebastião flower structure, São Paulo
DOI:
https://doi.org/10.5327/Z1519-874X2008000200007Keywords:
Costeiro Complex, Ribeira Fold Belt, Brasiliano CycleAbstract
The aim of this paper is to present lithochemical data from the granitoids found between Guarujá and São Sebastião in a segment of the Costeiro Complex in São Paulo, State, Brazil. This part of the Ribeira Folded Belt is composed of para-derived rocks on the eastern side, and ortho-derived rocks on the western side of the belt, organized in a ductile shear zone forming a positive flower structure, whose axis runs ENE-WSW. Large boudins of amphibolite occur within predominant kinzigitic gneisses along this axis. The intrusive basic protoliths of the amphibolites have a 580 Ma (U-Pb SHRIMP) crystallization age. SiO2 contents of the granitoids vary between 68 and 74%, corresponding to monzogranites and granodiorites. Some outcrops display mafic enclaves of quartz-monzodiorites. The granitoids show calc-alkaline affinity while their mafic enclaves tend towards an alkaline affinity. The lower content in SiO2 coupled with coherent differences on some trace element concentrations (e.g. Zr-Hf) contribute to clearly distinguish the enclaves from their country rocks and to suggest intense chemical interaction among the materials during crystallization. The REE pattern, the depletion in Sr, P-Ti, Ta-Nb, and the distribution of the samples on the R1-R2 diagram suggest a syn-collision island arc environment for generation of these rocks.Downloads
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Published
2008-10-01
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How to Cite
Marins e Dias Neto, C. de, Correia, C. T., Munhá, J. M. U., & Tassinari, C. C. G. (2008). Lithogeochemistry of granitoids in the São Sebastião flower structure, São Paulo . Geologia USP. Série Científica, 8(2), 101-114. https://doi.org/10.5327/Z1519-874X2008000200007