Características petrográficas y geoquímicas de los paragneises de Granja (Dominio Medio Coreaú, NW Ceará, Brasil)

A. J.F. Silva; M. R. Azevedo; B. Valle Aguado; J. A. Nogueira Neto; T. J.S. Santos; F. D.O. Silva

doi:10.3989/egeol.41750.326

Authors

A. J.F. Silva GeoBioTec, Departamento de Geociências, Universidade de Aveiro
M. R. Azevedo GeoBioTec, Departamento de Geociências, Universidade de Aveiro
B. Valle Aguado GeoBioTec, Departamento de Geociências, Universidade de Aveiro
J. A. Nogueira Neto Departamento de Geologia, Universidade Federal do Ceará
T. J.S. Santos Instituto de Geociências, Universidade Estadual de Campinas
F. D.O. Silva Departamento de Geologia, Universidade Federal do Ceará

DOI:

https://doi.org/10.3989/egeol.41750.326

Keywords:

Brasiliano granulite metamorphism, migmatitic paragneisses, provenance

Abstract

The Granja Granulite Complex (GGC) exposed in the Médio Coreaú Domain (NW Ceará, Brasil) consists mainly of garnet and sillimanite migmatitic paragneisses enclosing discontinuous lenses of mafic granulites and enderbites. According to the published geochronological data, this high-grade metamorphic belt represents a segment of the Paleoproterozoic basement intensely reworked during the Brasiliano / Pan-African Orogeny in the Neoproterozoic (600 Ma). The Granja paragneisses are strongly foliated rocks characterized by the alternance of dark garnet-biotite-sillimanite-rich layers and millimeter-thick leucocratic quartz-feldspathic bands, interpreted as indicative of incipient melting. As melt contents increase, layer-parallel leucosomes become thicker and a well-developed stromatic layering is defined. Both the gneissic and stromatic fabrics are strongly overprinted by a penetrative mylonitic foliation correlated to the last reactivation of the dextral NE-SW trending Granja Shear Zone (GCZ) that cuts across the studied area. Mineral assemblages and microstructures indicate that these rocks were affected by granulite-facies metamorphism and anatexis followed by decompression and cooling. In order to constrain the protolith composition of the Granja paragneisses, twelve whole-rock samples from the parts of the migmatitic paragneisses that appear to have undergone little or no melt extraction were analysed for major and trace elements. In the classification diagram of Herron (1988), the samples plot in the transition between the greywacke and the pelite fields, suggesting that the pre-metamorphic sequence was dominantly composed by shales and immature clastic sediments (greywackes). Their chondrite normalized REE patterns show a moderate LREE enrichment (LaN/YbN = 9.46–15.50), flat HREE profiles and negative Eu anomalies (Eu/Eu* = 0.63–0.82), closely resembling those of PAAS (Post-Archean average Australian Shale) and Early Proterozoic Greywackes. Geochemical data also suggest that the precursor sediments of the Granja paragneisses derived from source areas of felsic to intermediate composition and were deposited in a tectonically active continental margin / continental island arc setting.

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References

Abu El-Enen, M.M. (2008). Geochemistry and metamorphism of the Pan-African back-arc Malhaq volcano-sedimentary Neoproterozoic association, W. Kid area, SE Sinai, Egypt. Journal of African Earth Sciences, 51: 189–206. http://dx.doi.org/10.1016/j.jafrearsci.2008.01.004

Abu El-Enen, M.M. (2011). Geochemistry, provenance, and metamorphic evolution of Gabal Samra Neoproterozoic metapelites, Sinai, Egypt. Journal of African Earth Sciences, 59: 269–282. http://dx.doi.org/10.1016/j.jafrearsci.2010.11.002

Almeida, F.F.M.; Hasui, Y.; Brito Neves, B.B. & Fuck, R.A. (1981). Brazilian structural provinces: an introduction. Earth Sciences Reviews, 17: 1–29. http://dx.doi.org/10.1016/0012-8252(81)90003-9

Amaral, W.S.; Santos, T.J.S.; Wernick, E.; Nogueira Neto, J.A.; Dantas, E.L. & Matteini, M. (2012). High-pressure granulites from Cariré, Borborema Province, NE Brazil: Tectonic setting, metamorphic conditions and U-Pb, Lu-Hf and Sm-Nd geochronology. Gondwana Research, 22: 892–909. http://dx.doi.org/10.1016/j.gr.2012.02.011

Augustsson, C. & Bahlburg, H. (2003). Active or passive continental margin? Geochemical and Nd isotope constraints of metasediments in the backstop of a pre-Andean accretionary wedge in southernmost Chile (46°30'–48°30'S). In: Tracing Tectonic Deformation Using the Sedimentary Record (McCann, T. & Saintot, A.; Eds.), Geological Society, London, Special Publications, 208: 253–268.

Bhatia, M.R. & Crook, K.A.W. (1986). Trace element characteristics of graywackes and tectonic setting discrimination of sedimentary basins. Contributions to Mineralogy and Petrology, 92: 181–193. http://dx.doi.org/10.1007/BF00375292

Caby, R. (1989). Precambrian terranes of Benin-Nigeria and northeast Brazil and the Late Proterozoic south Atlantic fit. Geological Society of America Special Paper, 230: 145–158.

Cavalcante, J.C.; Vasconcelos, A.M.; Medeiros, M.F.; Paiva, L.P.; Gomes, F.E.M.; Cavalcante, S.N.; Cavalcante, J.E.; Melo, A.C.R.; Duarte Neto, V.C. & Benevides, H.C. (2003). Mapa Geológico do Estado do Ceará - 1:500.000, Fortaleza, Companhia de Pesquisa de Recursos Minerais (CPRM) - Geological Survey of Brazil.

Condie, K.C. (1993). Chemical composition and evolution of the upper continental crust: Contrasting results from surface samples and shales. Chemical Geology, 104: 1–37. http://dx.doi.org/10.1016/0009-2541(93)90140-E

Cordani, U.G.; Sato, K.; Teixeira, W.; Tassinari, C.C.G. & Basei, M.A.S. (2000). Crustal Evolution of the South American Platform. In: Tectonic Evolution of South America (Cordani, U. G.; Milani, E. J.; Thomaz Filho, A. & Campos, D. A.; Eds.), Sociedade Brasileira de Geologia, Rio de Janeiro, 19–40.

Evensen, N.M.; Hamilton, P.J. & O'Nions, R.K. (1978). Rare-earth abundances in chondritic meteorites. Geochimica et Cosmochimica Acta, 42: 1199–1212. http://dx.doi.org/10.1016/0016-7037(78)90114-X

Fetter, A.H.; Van Schmus, W.R.; Santos, T.J.S.; Nogueira Neto, J.A. & Arthaud, M.H. (2000). U/Pb and Sm/Nd Geochronological Constraints on the Crustal Evolution and Basement Architecture of Ceará State, NW Borborema Province, NE Brazil: Implications for the Existence of the Paleoproterozoic Supercontinent "Atlantica". Revista Brasileira de Geociências, 30: 102–106.

Gama Jr, T. (1992). Geologia do setor nordeste da zona de cisalhamento de Granja - noroeste do Ceará. PhD Thesis. Universidade Federal do Pará, Belém, Brasil, 174 pp.

Garcia, D.; Coelho, J.; Perrin, M. (1991). Fractionation between TiO2 and Zr as a measure of sorting within shale and sandstone series (northern Portugal). European Journal of Mineralogy, 3: 401–414. http://dx.doi.org/10.1127/ejm/3/2/0401

Herron, M.M. (1988). Geochemical classification of terrigenous sands and shales from core or log data. Journal of Sedimentary Petrology, 58: 820–829.

La Roche, H. (1968). Comportement géochimique différentiel de Na, K et Al dans les formations volcaniques et sédimentaires: un guide pour l'étude des formations métamorphiques et plutoniques. Comptes Rendus de l'Académie des Sciences de Paris, 267: 39–42.

Le Breton, N. & Thompson, A.B. (1988). Fluid-absent (dehydration) melting of biotite in metapelites in the early stages of crustal anatexis. Contributions to Mineralogy and Petrology, 99: 226–237. http://dx.doi.org/10.1007/BF00371463

McLennan, S.M. & Taylor, S.R. (1991). Sedimentary Rocks and Crustal Evolution: Tectonic Setting and Secular Trends. Journal of Geology, 99: 1–21. http://dx.doi.org/10.1086/629470

McLennan, S.M.; Hemming, S.; McDaniel, D.K. & Hanson, G.N. (1993). Geochemical approaches to sedimentation, provenance and tectonics. In: Processes Controlling the Composition of Clastic Sediments (Johnsson, M.J. & Basu, A.; Eds.), Geological Society of America Special Papers, 285: 21–40. http://dx.doi.org/10.1130/SPE284-p21

McLennan, S.M.; Hemming, S.R.; Taylor, S.R. & Eriksson, K.A. (1995). Early Proterozoic crustal evolution: Geochemical and Nd-Pb isotopic evidence from metasedimentary rocks, southwestern North America. Geochimica et Cosmochimica Acta, 59: 1153–1177. http://dx.doi.org/10.1016/0016-7037(95)00032-U

Moine, B. & La Roche, H. (1968). Nouvelle approche du problème d'origine des amphibolites à partir de leur composition chimique. Comptes Rendus de l'Académie des Sciences de Paris, 267: 2084–2087.

Monié, P.; Caby, R. & Arthaud, M.H. (1997). Timing of the Neoproterozoic Brasiliano Orogeny in northeast Brazil: 40Ar/39Ar ages and petrostructural data from Ceará. Precambrian Research, 81: 241–264. http://dx.doi.org/10.1016/S0301-9268(96)00037-X

Nance, W.B. & Taylor, S.R. (1976). Rare-Earth Element Patterns and Crustal Evolution, Australian Post-Archean Sedimentary-Rocks. Geochimica et Cosmochimica Acta, 40: 1539–1551. http://dx.doi.org/10.1016/0016-7037(76)90093-4

Nesbitt, H.W. & Young, G.M. (1982). Early Proterozoic climates and plate motions inferred from major element chemistry of lutites. Nature, 299: 715–717. http://dx.doi.org/10.1038/299715a0

Nesbitt, H.W. & Young, G.M. (1984). Prediction of some weathering trends of plutonic and volcanic rocks based on thermodynamic and kynetic considerations. Geochimica et Cosmochimica Acta, 48: 1523–1534. http://dx.doi.org/10.1016/0016-7037(84)90408-3

Nogueira Neto, J.A. (2000). Evolução Geodinâmica das Faixas Granulíticas de Granja e Cariré, Extremo Noroeste da Província Borborema. PhD Thesis, Instituto de Geociências e Ciências Exatas da Universidade Estadual Paulista (IGCE-UNESP), Rio Claro, São Paulo, Brasil, 170 pp.

Otamendi, J.E. & Patiño Douce, A.E. (2001). Partial melting of aluminous metagreywackes in the Northern Sierra de Comechingones, Central Argentina. Journal of Petrology, 42: 1751–1772. http://dx.doi.org/10.1093/petrology/42.9.1751

Pëto, P. (1976). An experimental investigation of melting reactions involving muscovite and paragonite in the silica saturated portion of the system K2O-Na2O-Al2O3-SiO2-H2O to 15 kbar total pressure. Programs in Experimental Petrology, Natural Environment Research Council 3rd report, 41–45.

Praxedes, I.F.; Silva, A.J.F.; Soares, W.C.; Magini, C.; Azevedo, M.R.; Nogueira Neto, J.A. & Fuck, R.A. (2012). Idade de Anatexia do Complexo Granja, Domínio Médio Coreaú (DMC), Província Borborema (PB) - Dados Iniciais. Anais do 46° Congresso Brasileiro de Geologia e 1° Congresso de Geologia dos Países de Língua Portuguesa, Santos, Brasil.

Roser, B.P. & Korsch, R.J. (1986). Discrimination of tectonic setting of sandstone-mudstone suites using SiO2 content and K2O/Na2O ratio. Journal of Geology, 94: 635–650. http://dx.doi.org/10.1086/629071

Roser, B.P. & Korsch, R.J. (1988). Provenance Signatures of Sandstone-Mudstone suites determined using discriminant function analysis of major-element data. Chemical Geology, 67: 119–139. http://dx.doi.org/10.1016/0009-2541(88)90010-1

Santos, T.J.S. (1993). Aspectos geológicos de uma área a sudeste de Granja, região NW do Ceará. M.Sc. Thesis, Instituto de Geociências e Ciências Exatas da Universidade Estadual Paulista (IGCE-UNESP), Rio Claro, São Paulo, Brasil, 159 pp.

Santos, T.J.S.; Fetter, A.H.; Hackspacher, P.C.; Van Schmus, W.R. & Nogueira Neto, J.A. (2008). Neoproterozoic tectonic and magmatic episodes in the NW segment of the Borborema Province, NE Brazil, during the assembly of the western Gondwana. Journal of South American Earth Sciences, 25: 271–284. http://dx.doi.org/10.1016/j.jsames.2007.05.006

Santos, T.J.S.; Fetter, A.H.; Van Schmus, W.R. & Hackspacher, P.C. (2009). Evidence for 2.35 to 2.30 Ga juvenile crustal growth in the northwest Borborema Province, NE Brazil In: Palaeoproterozoic Supercontinents and Global Evolution (Reddy, S.M.; Mazumder, R.; Evans, D.A.D.; Collins, A.S.; Eds.), Geological Society, London, Special Publications, 323: 271–281.

Spear, F.S.; Kohn, M.J.; Cheney, J.T. (1999). P-T paths from anatectic pelites. Contributions to Mineralogy and Petrology, 134: 17–32. http://dx.doi.org/10.1007/s004100050466

Werner, C.D. (1987). Saxonian granulites: a contribution to the geochemical diagnosis of original rocks in high-metamorphic complexes. Gerlands Beitraege zur Geophysik, 96: 271–290.