Crystallophysical and cristallochemical characterization of a tourmaline - (Fe) from pegmatite from the Solonópole region in the state of Ceará
DOI:
https://doi.org/10.51359/1980-8208.2023.261513Keywords:
pegmatite, tourmaline, electronic microprobe, single crystalAbstract
The Pegmatitic District of Solonópole-Banabuiú (DPSB) is located in the central-west portion of the State of Ceará, embedded in the paragneissic basement of the Ceará Central Domain of the Borborema Province. It is the most economically significant in the region and its main mineralizations are associated with the lithium-beryl-tantaliferous character of the bodies. In this research, a pegmatite located in the municipality of Solonópole in the DPSB was selected. It is classified as a mixed pegmatite between homogeneous and heterogeneous types, with no well-defined zoning. It is a complex pegmatite, forming replacement bodies (pockets) of muscovite, quartz and beryl, with well-developed crystals. It belongs to the Rare Earth Elements class of the LCT family. Its mineralogy differs from other pegmatites in the region due to the presence of lithium minerals, tourmaline presents a color variation from green to blue. The crystallochemical characterization was carried out by electron microprobe analysis and the sample obtained the following contents for major elements (Al2O3=34.18%, MgO=1.10%, FeO=11.44%) classified as elbaite/oxy-schorlite. The tourmalines of the Solonópole Pegmatite are oxy-species, falling in the limit of the field of granitic pegmatites and Li-rich aplites and endogranitic/endogreisen stage. Crystallophysical characterization through single crystal X-ray diffraction was performed on tourmaline samples, presenting a rhombohedral crystal structure, space group R3m and unit cell parameters being a=15.90 Å, b=15.90 Å and c= 7.12 Å, considered favorable for a Fe-rich tourmaline crystal.
References
Beurlen, H., Moura, O.J.M., Soares, D.R., Da Silva, M.R.R., Rhede, D. (2011). Geochemical and geological controls on the genesis of gem-quality “Paraíba tourmaline” in granitic pegmatites from Northeastern Brazil. Canadian Mineralogist, 49:277- 300.
Beurlen, H., Thomas, R., Da Silva, M.R.R., Müller, A., Rhede, D., Soares, D.R. (2014). Perspectives for Li- and Ta-mineralization in the Borborema Pegmatite Province, NE Brazil: A review. Journal of South American Earth Sciences, 56:110-127.
Castro, N.A. (2004). Evolução geológica proterozóica da região entre Madalena e Taperuaba Domínio Tectônico Ceará Central (Província Borborema), São Paulo: s.n.
Cavalcante, J.C. et al. (2003). Mapa geológico do Estado do Ceará – Escala 1:500.000. Serviço Geológico do Brasil MME/CPRM.
Černý, P. & Ercit, T. S. (2005). The classification of granitic pegmatites revisited. The Canadian mineralogist, 43 (6): 2005-2026.
Fetter, A. et al. (2003). Evidence for Neoproterozoic continental arc magmatism in the Santa Quitéria Batholith of Ceará State, NW Borborema Province, NE Brazil: implications for the assembly of West Gondwana. Gondwana Research, Volume 6.
Hollanda, M.H.B.M., Archanjo, C.J., Souza, L.C., Armstrong, R., Vasconcelos, P.M. (2010). Cambrian mafic to felsic magmatism and its connections with transcurrent shear zones of the Borborema Province (NE Brazil): Implications for the late assembly of the West Gondwana. Precambrian Research, 178: 1-14.
Jardim de Sá, E.F. (1994). A Faixa Seridó (Província Borborema, NE do Brasil) e o seu Significado Geodinâmico na Cadeia Brasiliana/Pan-Africana. UNB, Tese de Doutorado, 803 p.
Kozuch, M. (2003). Isotopic and trace elemento geochemistry of early neoproterozoic gneissic and metavolcanic rocks in the Cariris Velhos orogen of the Borborema Province, Brazil, and theis bearing on tectonic setting. Ph.D. Thesis, University of Kansas, Lawrence, KS. USA.
Kozuch, M., Bittar, S.M.B., Van Schmus, W.R., Brito Neves, B.B. (1997). Late Mesoprotrozoic and middle Neoproterozoic magmatism in the Zona Transversal of Borborema Province, N.E. Brasil. 17° Simposio de Geologia do Nordeste, Fortaleza, Brasil, Extended Abstracts, 15, 47-49.
Santos, E.J. (1995). O Complexo Granítico Lagoa das Pedras: Acresção e Colisão na Região de Floresta (Pernambuco), Província Borborema. USP/IG, Tese de Doutorado, 219 p.
Santos, L.; Guimarães, I.P.; Silva Filho, A.F.; Farias, D.J.S.; Lima, J.V.; Antunes, J.V. (2014). Magmatismo ediacarano extensional na Província Borborema, NE Brasil: Pluton Serra Branca. Comunicações Geológicas, 101, Especial I, 199-203.
Scorza, E.P. (1944). Província Pegmatítica da Borborema (Nordeste do Brasil). DNPM/DGM (Boletim n. 112). Rio de Janeiro, 55p.
Souza, J. (1985). Geologia dos Pegmatitos de Metais Raros da Região W e NW de Solonópole – CE (Brasil), Fortaleza: s.n.
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