ABSTRACT:
The Monte de Trigo alkaline suite is a SiO2-undersaturated syenite-gabbroid association from the Serra do Mar alkaline province. Eudialyte-group minerals (EGMs) occur in one nepheline microsyenite dyke, associated with aegirine-augite, wöhlerite, låvenite, magnetite, zircon, titanite, britholite, and pyrochlore. Major compositional variations include Si (25.09- 25.57 apfu ), Nb (0.31- 0.76 apfu ), Fe (1.40-2.13 apfu ), and Mn (1.36- 2.08 apfu ). The EGMs also contain relatively high contents of Ca (6.13- 7.10 apfu ), moderate enrichment of rare earth elements (0.38-0.67 apfu ), and a relatively low Na content (11.02-12.28 apfu ), which can be correlated with their transitional agpaitic assemblage. EGM compositions indicate a complex solid solution that includes eudialyte, kentbrooksite, feklichevite, zirsilite-(Ce), georgbarsanovite, and manganoeudialyte components. EGM trace element analyses show low Sr and Ba contents and a negative Eu/Eu* anomaly, which are interpreted as characteristic of the parental magma due to the previous fractionation of plagioclase and/or alkali feldspar. The EGMs from the dyke border have higher contents of Fe, Sr (2,161-2,699 ppm), Mg (1,179-3,582 ppm), and Zn (732- 852 ppm) than those at the dyke center. These differences are related to the incorporation of xenoliths and xenocrysts of melatheralitic host rock into the nepheline-syenitic magma followed by crystal-melt diffusive exchange.
Keywords:
mineral chemistry; agpaitic rocks; Serra do Mar alkaline province
RESUMO:
A suíte alcalina do Monte de Trigo é uma associação sienítico-gabroide que pertence à província alcalina da Serra do Mar. Minerais do grupo da eudialita (EGMs) ocorrem em um dique de nefelina microssienito associados a egirina-augita, wöhlerita, lavenita, magnetita, zircão, titanita, britolita e pirocloro. As principais variações composicionais incluem Si (25,09-25,57 apfu ), Nb (0,31-0,76 apfu ), Fe (1,40-2,13 apfu ) e Mn (1,36-2,08 apfu ). Os EGMs também contêm concentrações relativamente altas de Ca (6,13-7,10 apfu ), enriquecimento moderado de elementos terras raras (0,38-0,67 apfu ) e concentrações relativamente baixas de Na (11,02-12,28 apfu ), o que pode ser correlacionado com uma assembleia agpaítica transicional. As composições dos EGMs indicam uma solução sólida complexa entre os componentes eudialita, kentbrooksita, feklichevita, zirsilita-(Ce), georgbarsanovita e manganoeudialita. Análises de elementos traços das EGMs mostram baixas concentrações de Sr e Ba e anomalia negativa de Eu/Eu*, que são interpretadas como uma característica do magma parental por conta do fracionamento de plagioclásio e/ou feldspato alcalino. Os EGMs da borda do dique possuem concentrações maiores de Fe, Sr (2.161-2.699 ppm), Mg (1.179-3.582 ppm) and Zn (732-852 ppm) que aqueles do centro do dique. Essas diferenças estão relacionadas com a incorporação de xenólitos e xenocristais da rocha encaixante melateralítica no magma nefelina-sienítico seguido de trocas difusivas entre os cristais e o líquido.
Palavras-chave:
química mineral; rochas agpaíticas, província alcalina da Serra do Mar
INTRODUCTION
The eudialyte group minerals (EGMs) consist of various Na-, Ca-, and Zr-rich cyclosilicates with a wide compositional variation. Significant amounts of other elements, such as Fe, Mn, Nb, rare earth elements (REE), Sr, and Cl are reported in EGM compositions (Johnsen & Gault 1997Johnsen O., Gault R.A. 1997. Chemical variation in eudialyte. Neues Jahrbuch für Mineralogie-Abhandlungen , 171:215-237., Johnsen & Grice 1999Johnsen O., Grice J.D. 1999. The crystal chemistry of the eudialyte group. The Canadian Mineralogist ,37:865-891., Schilling et al. 2011bSchilling J., Wu F.-Y., McCammon C., Wenzel T., Marks M.A.W., Pfaff K., Jacob D.E., Markl G. 2011b. The compositional variability of eudialyte-group minerals. Mineralogical Magazine , 75(1):87-115. DOI: 10.1180/minmag.2011.075.1.87
https://doi.org/10.1180/minmag.2011.075....
). According to the International Mineralogical Association (Johnsen et al. 2003Johnsen O., Ferraris G., Gault R.A., Grice J.D., Kampf A.R., Pekov I.V. 2003. The nomenclature of eudialyte-group minerals. The Canadian Mineralogist ,41:785-794. DOI: 10.2113/gscanmin.41.3.785
https://doi.org/10.2113/gscanmin.41.3.78...
), the general formula of the EGMs is Na12[N(4) ]3[M(1) ]6[M(2) ]3[M(3) ][M(4) ]Zr3(Si24O72)(O,OH,H2O)4
X
2 , in which the common elements assigned to each site are as it follows:
-
■ Si at M(4);
-
■ Nb, Si, Ti, and W at M(3);
-
■ Fe, Mn, Na, Zr, K, and H3O at M(2);
-
■ Ca, Mn, and Fe at M(1) ;
-
■ Na, REE, Sr, K, Ca, Mn, and H3O at N(4);
-
■ Cl, OH, F, and CO3 at X.
Rastsvetaeva & Chukanov (2012Rastsvetaeva R.K., Chukanov N.V. 2012. Classification of eudialyte-group minerals. Geology of Ore Deposits , 54(7):487-497. DOI: 10.1134/S1075701512070069
https://doi.org/10.1134/S107570151207006...
) list 25 known species of EGMs, and recently a new member named Ilyukhinite was described (Chukanov et al. 2015Chukanov N.V., Rastsvetaeva R.K., Rozenberg K.A., Aksenov S.M., Pekov I.V., Belakovskiy D.I., Kristiansen R. 2015. Ilyukhinite, IMA 2015-065. CNMNC Newsletter No. 28, December 2015, page 1860; Mineralogical Magazine , 79(6):1859-1864. DOI: 10.1180/minmag.2015.079.7.18
https://doi.org/10.1180/minmag.2015.079....
). This great diversity is the result of the compositional and structural complexity of the group.
Eudialyte was first described by Stromeyer (1819Stromeyer F. 1819. Summary of meeting 16 December 1819. Göttingische gelehrte Anzeigen , 3:1993-2000.) as one of the major constituents of nepheline syenites from the Ilímaussaq Complex, Greenland. Since then, EGMs have been recognized in nearly all occurrences of agpaitic rocks, i.e., peralkaline nepheline syenites (and phonolites) that contain complex silicates of Zr, Ti, REE, F, and other volatiles (Sørensen 1997Sørensen H. 1997. The agpaitic rocks, an overview. Mineralogical Magazine , 61(4):485-498., Le Maitre 2002Le Maitre R.W. (Ed.) 2002. Igneous rocks: a classification of igneous rocks and glossary of terms.Cambridge, Cambridge University Press, 236 p.). EGMs have been described in agpaitic rocks from Khibiny and Lovozero, Kola Peninsula (Khomyakov 1995Khomyakov A.P. 1995. Mineralogy of hiperagpaitic rocks . Oxford, Oxford Scientific Publications, Clarendon Press, 223 p., Johnsen & Gault 1997Johnsen O., Gault R.A. 1997. Chemical variation in eudialyte. Neues Jahrbuch für Mineralogie-Abhandlungen , 171:215-237., Schilling et al. 2011bSchilling J., Wu F.-Y., McCammon C., Wenzel T., Marks M.A.W., Pfaff K., Jacob D.E., Markl G. 2011b. The compositional variability of eudialyte-group minerals. Mineralogical Magazine , 75(1):87-115. DOI: 10.1180/minmag.2011.075.1.87
https://doi.org/10.1180/minmag.2011.075....
); Mont Saint-Hilaire, Canada (Johnsen & Gault 1997Johnsen O., Gault R.A. 1997. Chemical variation in eudialyte. Neues Jahrbuch für Mineralogie-Abhandlungen , 171:215-237., Johnsen & Grice 1999Johnsen O., Grice J.D. 1999. The crystal chemistry of the eudialyte group. The Canadian Mineralogist ,37:865-891., Schilling et al. 2011bSchilling J., Wu F.-Y., McCammon C., Wenzel T., Marks M.A.W., Pfaff K., Jacob D.E., Markl G. 2011b. The compositional variability of eudialyte-group minerals. Mineralogical Magazine , 75(1):87-115. DOI: 10.1180/minmag.2011.075.1.87
https://doi.org/10.1180/minmag.2011.075....
); Langesundsfjord, Norway (Andersen et al. 2010Andersen T., Erambert M., Larsen A.O., Selbekk R.S. 2010. Petrology of nepheline syenite pegmatites in the Oslo Rift, Norway: zirconium silicate mineral assemblages as indicators of alkalinity and volatile fugacity in mildly agpaitic magma. Journal of Petrology , 51(11):2303-2325. DOI: 10.1093/petrology/egq058
https://doi.org/10.1093/petrology/egq058...
, Schilling et al. 2011bSchilling J., Wu F.-Y., McCammon C., Wenzel T., Marks M.A.W., Pfaff K., Jacob D.E., Markl G. 2011b. The compositional variability of eudialyte-group minerals. Mineralogical Magazine , 75(1):87-115. DOI: 10.1180/minmag.2011.075.1.87
https://doi.org/10.1180/minmag.2011.075....
); Tamazeght, Morocco (Schilling et al. 2009Schilling J., Marks M., Wenzel T., Markl G. 2009. Reconstruction of magmatic to subsolidus processes in an agpaitic system using eudialyte textures and composition: a case study from Tamazeght, Morocco. The Canadian Mineralogist ,47(2):351-365. DOI: 10.3749/canmin.47.2.351
https://doi.org/10.3749/canmin.47.2.351...
, Schilling et al. 2011bSchilling J., Wu F.-Y., McCammon C., Wenzel T., Marks M.A.W., Pfaff K., Jacob D.E., Markl G. 2011b. The compositional variability of eudialyte-group minerals. Mineralogical Magazine , 75(1):87-115. DOI: 10.1180/minmag.2011.075.1.87
https://doi.org/10.1180/minmag.2011.075....
); Poços de Caldas, Brazil (Johnsen & Gault 1997Johnsen O., Gault R.A. 1997. Chemical variation in eudialyte. Neues Jahrbuch für Mineralogie-Abhandlungen , 171:215-237., Ulbrich & Ulbrich 2000Ulbrich H.H.G.J., Ulbrich M.N.C. 2000. The lujavrite and khibinite bodies in the Poços de Caldas alkaline massif, southeastern Brazil: a structural and petrographic study. Revista Brasileira de Geociências , 30(4):615-622., Ulbrich et al. 2005Ulbrich H.H.G.J., Demaiffe D., Vlach S.R.F., Ulbrich M.N.C. 2005. Structure and origin of the Poços de Caldas alkaline massif, SE Brazil Comin-Chiaramonti P., Gomes C.B. (eds.) Mesozoic to Cenozoic alkaline magmatism in the Brazilian Platform . São Paulo, Edusp/FAPESP, p. 367-418., Schilling et al. 2011bSchilling J., Wu F.-Y., McCammon C., Wenzel T., Marks M.A.W., Pfaff K., Jacob D.E., Markl G. 2011b. The compositional variability of eudialyte-group minerals. Mineralogical Magazine , 75(1):87-115. DOI: 10.1180/minmag.2011.075.1.87
https://doi.org/10.1180/minmag.2011.075....
); Cerro Boggiani, Paraguay (Gomes et al. 1996Gomes C.B., Laurenzi M.A., Censi P., De Min A., Velázquez V.F., Comin-Chiaramonti P. 1996. Alkaline magmatism from northern Paraguay (Alto Paraguay): a Permo-Triassic province : Comin-Chiaramonti P., Gomes C.B. (eds.) Alkaline Magmatism in Central-Eastern Paraguay. Relationships with Coeval Magmatism in Brazil . São Paulo, Edusp/Fapesp, p. 223-230., Carbonin et al. 2005Carbonin S., Liziero F., Fuso C. 2005. Mineral chemistry of accessory minerals in alkaline complexes from the Alto Paraguay Province Comin-Chiaramonti P., Gomes C.B. (eds.) Mesozoic to Cenozoic alkaline magmatism in the Brazilian Platform . São Paulo, Edusp/FAPESP, p. 149-158.); Pilanesberg, South Africa (Mitchell & Liferovich, 2006Mitchell R., Liferovich R. 2006. Subsolidus deuteric/hydrothermal alteration of eudialyte in lujavrite from the Pilansberg alkaline complex, South Africa. Lithos , 91(1-4):352-372. DOI: 10.1016/j.lithos.2006.03.025
https://doi.org/10.1016/j.lithos.2006.03...
, Schilling et al. 2011aSchilling J., Marks M.A.W., Wenzel T., Vennemann T., Horváth L., Tarassoff P., Jacob D.E., Markl G. 2011a. The magmatic to hydrothermal evolution of the intrusive Mont Saint-Hilaire Complex: insights into the late-stage evolution of peralkaline rocks. Journal of Petrology , 52(11):2147-2185. DOI: 10.1093/petrology/egr042
https://doi.org/10.1093/petrology/egr042...
); Sushina Hill, India (Mitchell & Chakrabarty, 2012Mitchell R.H., Chakrabarty A. 2012. Paragenesis and decomposition assemblage of a Mn-rich eudialyte from the Sushina peralkaline nepheline syenite gneiss, Paschim Banga, India. Lithos , 152:218-226. DOI: 10.1016/j.lithos.2012.02.003
https://doi.org/10.1016/j.lithos.2012.02...
); Agua de Pau volcano, Azores, Portugal (Ridolfi et al. 2003Ridolfi F., Renzulli A., Santi P., Upton B.G.J. 2003. Evolutionary stages of crystallization of weakly peralkaline syenites: evidence from ejecta in the plinian deposits of Agua de Pau volcano (São Miguel, Azores Islands). Mineralogical Magazine , 67(4):749-767. DOI: 10.1180/0026461036740131
https://doi.org/10.1180/0026461036740131...
); and Kilombe volcano, Kenya Rift Valley (Ridolfi et al. 2006Ridolfi F., Renzulli A., Macdonald R., Upton B.G.J. 2006. Peralkaline syenite autoliths from Kilombe volcano, Kenya Rift Valley: evidence for subvolcanic interaction with carbonatitic fluids. Lithos , 91(1-4):373-392. DOI: 10.1016/j.lithos.2006.03.026
https://doi.org/10.1016/j.lithos.2006.03...
). The typical minerals associated with EGMs include alkali feldspar, nepheline, sodalite, aegirine, arfvedsonite, and several complex Zr-, Nb-, Ti-, and REE-bearing silicates, such as astrophyllite, lamprophyllite, rosenbuschite, rinkite, and wöhlerite (e.g., Sørensen 1997Sørensen H. 1997. The agpaitic rocks, an overview. Mineralogical Magazine , 61(4):485-498., Andersen et al. 2010Andersen T., Erambert M., Larsen A.O., Selbekk R.S. 2010. Petrology of nepheline syenite pegmatites in the Oslo Rift, Norway: zirconium silicate mineral assemblages as indicators of alkalinity and volatile fugacity in mildly agpaitic magma. Journal of Petrology , 51(11):2303-2325. DOI: 10.1093/petrology/egq058
https://doi.org/10.1093/petrology/egq058...
, Marks et al. 2011Marks M.A.W., Hettmann K., Schilling J., Frost B.R., Markl G. 2011. The mineralogical diversity of alkaline igneous rocks: critical factors for the transition from miaskitic to agpaitic phase assemblages. Journal of Petrology , 52(3):439-455. DOI: 10.1093/petrology/egq086
https://doi.org/10.1093/petrology/egq086...
, Schilling et al. 2011bSchilling J., Wu F.-Y., McCammon C., Wenzel T., Marks M.A.W., Pfaff K., Jacob D.E., Markl G. 2011b. The compositional variability of eudialyte-group minerals. Mineralogical Magazine , 75(1):87-115. DOI: 10.1180/minmag.2011.075.1.87
https://doi.org/10.1180/minmag.2011.075....
).
The present paper reports the occurrence of EGMs from the alkaline suite of Monte de Trigo, a small island (ca. 1 km2) situated near the towns of Sao Paulo and Rio de Janeiro, at the western border of the Santos Basin (23º53'S, 45º47'W), in southeastern Brazil. They describes major and trace element analyses of these EGMs, and their composition is discussed in terms of site assignment and possible ideal components. The objectives of the study were to characterize the EGMs at Monte de Trigo and to understand how its petrological environment influences the major and trace element compositions of the EGMs.
MAGMATIC CONTEXT
Several late cretaceous alkaline occurrences and widespread lamprophyre dyke swarms intrude the Neoproterozoic Ribeira belt in southeastern Brazil and constitute the Serra do Mar Alkaline Province (Fig. 1A; Almeida 1983Almeida F.F.M. 1983. Relações tectônicas das rochas alcalinas mesozóicas da região meridional da plataforma sul-americana. Revista Brasileira de Geociências , 13(3):39-158., Thompson et al. 1998Thompson R.N., Gibson S.A., Mitchell J.G., Dickin A.P., Leonardos O.H., Brod J.A., Greenwood J.C. 1998. Migrating Cretaceous-Eocene magmatism in the Serra do Mar Alkaline Province, SE Brasil: melts from the deflected Trindade Mantle Plume? Journal of Petrology , 39(8):1493-1526. DOI: 10.1093/petroj/39.8.1493
https://doi.org/10.1093/petroj/39.8.1493...
, Riccomini et al. 2005Riccomini C., Velázquez V.F., Gomes C.B. 2005. Tectonic controls of the Mesozoic and Cenozoic alkaline magmatism in Central-Southeastern Brazilian Platform Comin-Chiaramonti P., Gomes C.B. (eds.) Mesozoic to Cenozoic alkaline magmatism in the Brazilian Platform . São Paulo, Edusp/FAPESP, p. 31-55., Brotzu et al. 2005Brotzu P., Melluso L., D'Amelio F., Lustrino M. 2005. Potassic dykes and intrusions of the Serra do Mar Igneous Province (SE Brazil) Comin-Chiaramonti P., Gomes C.B. (eds.) Mesozoic to Cenozoic alkaline magmatism in the Brazilian Platform . São Paulo, Edusp/FAPESP, p. 443-472.). This province is part of an extensive Meso-Cenozoic tholeiitic-alkaline-carbonatitic magmatism that is spread over the central and southeastern regions of the Brazilian Platform (Morbidelli et al. 1995Morbidelli L., Gomes C.B., Beccaluva L., Brotzu P., Conte A.M., Ruberti E., Traversa G. 1995. Mineralogical, petrological and geochemical aspects of alkaline and alkaline-carbonatite associations from Brazil. Earth-Science Reviews , 39(3):135-168. DOI: 10.1016/0012-8252(95)00031-3
https://doi.org/10.1016/0012-8252(95)000...
, Peate 1997Peate D.W. 1997. The Paraná-Etendeka Province Mahoney J.J., Coffin M.F. (eds.) Large Igneous Provinces . Geophysical Monograph 100. Washington, American Geophysical Union, p. 217-245., Comin-Chiaramonti & Gomes 2005Comin-Chiaramonti P., Gomes C.B. 2005. Mesozoic to Cenozoic alkaline magmatism in the Brazilian Platform . São Paulo, Edusp/FAPESP, 752 p.). Syenites and nepheline syenites of miaskitic affinity (i.e., nepheline syenites containing zircon or titanite or molar (Na2O+K2O)/Al2O3 < 1 in bulk-rock composition; Sørensen 1997Sørensen H. 1997. The agpaitic rocks, an overview. Mineralogical Magazine , 61(4):485-498., Le Maitre 2002Le Maitre R.W. (Ed.) 2002. Igneous rocks: a classification of igneous rocks and glossary of terms.Cambridge, Cambridge University Press, 236 p.) prevail in many occurrences in the Serra do Mar Alkaline Province (Almeida 1983Almeida F.F.M. 1983. Relações tectônicas das rochas alcalinas mesozóicas da região meridional da plataforma sul-americana. Revista Brasileira de Geociências , 13(3):39-158., Brotzu et al. 2005Brotzu P., Melluso L., D'Amelio F., Lustrino M. 2005. Potassic dykes and intrusions of the Serra do Mar Igneous Province (SE Brazil) Comin-Chiaramonti P., Gomes C.B. (eds.) Mesozoic to Cenozoic alkaline magmatism in the Brazilian Platform . São Paulo, Edusp/FAPESP, p. 443-472.). Mafic-ultramafic intrusive lithologies only occur as small, cumulate bodies associated with the syenitic stocks, such as in São Sebastião (Enrich et al. 2005Enrich G.E.R., Azzone R.G., Ruberti E., Gomes C.B., Comin-Chiaramonti P. 2005. Itatiaia, Passa Quatro and São Sebastião Island, the major alkaline syenitic complexes from the Serra do Mar region Comin-Chiaramonti P., Gomes C.B. (eds.) Mesozoic to Cenozoic alkaline magmatism in the Brazilian Platform . São Paulo, Edusp/FAPESP, p. 419-442.) and Morro de São João (Brotzu et al. 2007Brotzu P., Melluso L., Bennio L., Gomes C.B., Lustrino M., Morbidelli L., Morra V., Ruberti E., Tassinari C., D'Antonio M. 2007. Petrogenesis of the Early Cenozoic potassic alkaline complex of Morro de São João, southeastern Brazil. Journal of South American Earth Science , 24(1):93-115. DOI: 10.1016/j.jsames.2007.02.006
https://doi.org/10.1016/j.jsames.2007.02...
), except for the Ponte Nova mafic-ultramafic massif, where felsic rocks are nearly absent (Azzone et al. 2009Azzone R.G., Ruberti E., Enrich G.E.R., Gomes C.B. 2009. Geologia e geocronologia do maciço alcalino máfico-ultramáfico Ponte Nova (SP-MG). Geologia USP Série Científica, 9(2):23-46. DOI: http://dx.doi.org/10.5327/z1519-874x2009000200002
http://dx.doi.org/10.5327/z1519-874x2009...
). The presence of agpaitic rocks (i.e., nepheline syenites and phonolites with molar (Na2O+K2O)/Al2O3 > 1 and complex silicates of Zr, Ti, REE, and F and others volatiles; Sørensen 1997Sørensen H. 1997. The agpaitic rocks, an overview. Mineralogical Magazine , 61(4):485-498., Le Maitre 2002Le Maitre R.W. (Ed.) 2002. Igneous rocks: a classification of igneous rocks and glossary of terms.Cambridge, Cambridge University Press, 236 p.) is restricted to a few localities in this province, usually in small volumes associated with large miaskitic bodies, as in the Poços de Caldas, Itatiaia, and Passa Quatro massifs (Fig. 1A; Brotzu et al. 1992Brotzu P., Barbieri M., Beccaluva L., Garbarino C., Gomes C.B., Macciotta G., Melluso L., Morbidelli L., Ruberti E., Sígolo J.B., Traversa G. 1992. Petrology and geochemistry of the Passa Quatro alkaline complex, Southeastern Brazil. Journal of South American Earth Science , 6(4):237-252. DOI: 10.1016/0895-9811(92)90044-Y
https://doi.org/10.1016/0895-9811(92)900...
, Brotzu et al. 1997Brotzu P., Gomes C.B., Melluso L., Morbidelli L., Morra V., Ruberti E. 1997. Petrogenesis of coexisting SiO2-undersaturated to SiO2-oversaturated felsic igneous rocks: The alkaline complex of Itatiaia, southeastern Brazil. Lithos , 40(2-4):133-156. DOI: 10.1016/S0024-4937(97)00007-8
https://doi.org/10.1016/S0024-4937(97)00...
, Ulbrich & Ulbrich 2000Ulbrich H.H.G.J., Ulbrich M.N.C. 2000. The lujavrite and khibinite bodies in the Poços de Caldas alkaline massif, southeastern Brazil: a structural and petrographic study. Revista Brasileira de Geociências , 30(4):615-622., Enrich et al. 2005Enrich G.E.R., Azzone R.G., Ruberti E., Gomes C.B., Comin-Chiaramonti P. 2005. Itatiaia, Passa Quatro and São Sebastião Island, the major alkaline syenitic complexes from the Serra do Mar region Comin-Chiaramonti P., Gomes C.B. (eds.) Mesozoic to Cenozoic alkaline magmatism in the Brazilian Platform . São Paulo, Edusp/FAPESP, p. 419-442., Ulbrich et al. 2005Ulbrich H.H.G.J., Demaiffe D., Vlach S.R.F., Ulbrich M.N.C. 2005. Structure and origin of the Poços de Caldas alkaline massif, SE Brazil Comin-Chiaramonti P., Gomes C.B. (eds.) Mesozoic to Cenozoic alkaline magmatism in the Brazilian Platform . São Paulo, Edusp/FAPESP, p. 367-418.).
(A) Geological map of the Serra do Mar alkaline province and surrounding area in southeastern Brazil, modified from Almeida (1983Almeida F.F.M. 1983. Relações tectônicas das rochas alcalinas mesozóicas da região meridional da plataforma sul-americana. Revista Brasileira de Geociências , 13(3):39-158.). Inset: simplified geological map of Monte de Trigo Island (after Enrich et al. 2009Enrich G.E.R., Ruberti E., Gomes C.B. 2009. Geology and geochronology of Monte de Trigo Island alkaline suite, southeastern Brazil. Revista Brasileira de Geociências , 39(1):67-80.); (B) Field relations of the EGM-bearing nepheline microsyenite dyke of the Monte de Trigo suite; (C) Detail of (B) showing corroded melatheralite xenoliths at the dyke border.
The Monte de Trigo alkaline suite (86.6 Ma, Enrich et al. 2009Enrich G.E.R., Ruberti E., Gomes C.B. 2009. Geology and geochronology of Monte de Trigo Island alkaline suite, southeastern Brazil. Revista Brasileira de Geociências , 39(1):67-80.) is a small, SiO2-undersaturated syenite-gabbroid intrusive suite (Fig. 1A) that belongs to the Serra do Mar alkaline province. According to Enrich et al. (2009Enrich G.E.R., Ruberti E., Gomes C.B. 2009. Geology and geochronology of Monte de Trigo Island alkaline suite, southeastern Brazil. Revista Brasileira de Geociências , 39(1):67-80.), the alkaline suite is composed of different pulses of undersaturated alkaline magmas. The oldest unit comprises a cumulate nepheline-bearing olivine melagabbros, melatheralites (i.e., melanocratic nepheline gabbro, Le Maitre 2002Le Maitre R.W. (Ed.) 2002. Igneous rocks: a classification of igneous rocks and glossary of terms.Cambridge, Cambridge University Press, 236 p.) and clinopyroxenites with wide modal variations and layering structures. A leucocratic medium-to-coarse-grained nepheline syenite and nepheline-bearing alkali feldspar syenite intrude the cumulate mafic-ultramafic unit and compose most of the area of the suite. Alkali feldspar, hedenbergite, hastingsite, and biotite are early magmatic phases, whereas nepheline and analcime are late-crystallized phases. Accessory minerals include apatite, magnetite, and titanite and characterize a miaskitic association. Miaskitic and agpaitic nepheline microsyenite dykes cut the cumulate mafic-ultramafic body and the nepheline syenite stock and are interpreted as late-stage differentiates of the nepheline syenite (Enrich et al. 2009Enrich G.E.R., Ruberti E., Gomes C.B. 2009. Geology and geochronology of Monte de Trigo Island alkaline suite, southeastern Brazil. Revista Brasileira de Geociências , 39(1):67-80.).
NEPHELINE MICROSYENITE DYKES
Miaskitic nepheline microsyenites have hypidiomorphic to allotriomorphic texture with early crystallized alkali feldspar, hastingsite, titanite, apatite, and magnetite, followed by aegirine-augite and late-crystallized nepheline and sodalite. Agpaitic nepheline microsyenites are less abundant, vary from fine-to-medium-grained inequigranular seriate texture to equigranular aplitic texture, and the origin of these dykes is interpreted as having crystallized from a more evolved magma fraction than the miaskitic microsyenites ones. Alkali feldspar, nepheline, aegirine-augite, katophorite, magnetite, wöhlerite, hiortdahlite, and apatite are early crystallized phases, whereas sodalite, analcime, låvenite, zircon, zirconolite, baddeleyite, pyrochlore, and britholite are late-crystallized phases. Post-magmatic minerals include fluorite, rutile, calcite, and pyrite.
Only one agpaitic nepheline microsyenite dyke contains EGMs (Fig. 1B). This dyke is 50 cm wide and intrudes melatheralites at the northern coast of the island. The dyke exhibits an equigranular aplitic texture, which suggests co-precipitation of most of the phases. Major phases include mesoperthitic alkali feldspar (~45 vol%), nepheline (~35 vol%), and aegirine to aegirine-augite (~10 vol%). EGMs (~2 vol%) are the most abundant accessory phases. These minerals are colorless, subhedral, hexagonal- to round-shaped, and exhibit low birefringence and moderate relief (Fig. 2). Other accessory phases include Mn-rich magnetite and subhedral wöhlerite, each less than 1 vol%. Interstitial titanite, zircon, and britholite occur as late- to post-magmatic phases. The EGM-bearing nepheline microsyenite is classified as low agpaitic or transitional agpaitic (Khomyakov 1995Khomyakov A.P. 1995. Mineralogy of hiperagpaitic rocks . Oxford, Oxford Scientific Publications, Clarendon Press, 223 p., Sørensen 1997Sørensen H. 1997. The agpaitic rocks, an overview. Mineralogical Magazine , 61(4):485-498.) in accordance with its accessory minerals.
Near the border, the EGM-bearing dyke shows an increase in the mafic mineral content, locally up to 25 vol%, as well as some mafic aggregates (Figs. 1C and 3A). The latter is composed of aegirine-augite and magnetite (Fig. 3B) and is interpreted as corroded and re-equilibrated xenoliths and/or xenocrysts of the melatheralite host-rock. Accessory minerals at the dyke border are EGMs and låvenite (Figs. 2C and 3B). Late-magmatic phases include poikilitic titanite, zirconolite, pyrochlore, and apatite.
Photomicrographs of the EGMs from the Monte de Trigo alkaline suite. (A) Granular EGM in association with tabular mesoperthitic feldspar, prismatic aegirine-augite and subhedral magnesiokatophorite and nepheline grains (dyke border); (B) Rounded EGM grains with alkali feldspar and nepheline (dyke center); (C) Granular EGMs, anhedral låvenite, and prismatic aegirine-augite with alkali feldspar and nepheline (dyke border). Mineral abbreviations: Ae-aug, aegirine-augite; Afs, alkali feldspar; Eud, eudialyte; Låv, låvenite; Mkt, magnesiokatophorite; Ne, nepheline.
(A) Contact between the EGM-bearing nepheline microsyenite dyke (left) and the melatheralite host rock (right) from Monte de Trigo; (B) Detail of (A) showing aegirine-augite and magnetite mafic aggregate near EGM and låvenite grains; (C) Detail of (A) showing the augite relict core with andradite border (top) and part of biotite, magnesiokatophorite, and aegirine-augite pseudomorph after augite (bottom). Mineral abbreviations: Ae-aug, aegirine-augite; Adr, andradite; Afs, alkali feldspar; Aug, augite; Bt, biotite; Eud, eudialyte; Låv, låvenite; Mkt, magnesiokatophorite.
The melatheralite host rock was transformed into a metasomatic granofels on a centimeter scale near the contact with the dyke, by its reaction with the alkaline volatile-rich liquid. Olivine, augite, and plagioclase from melatheralite were replaced by aegirine-augite, magnesiokatophorite, biotite, magnetite, and potassic feldspar (Fig. 3A). Aegirine-augite is the most abundant mineral within the first millimeter of the granofels. The granofels also has relict cores of augite with andradite rims, biotite, and magnesiokatophorite pseudomorphs after augite and masses of potassic feldspar after plagioclase (Fig. 3A and 3C).
ANALYTICAL METHODS
Major element analyses of the EGMs were performed on standard carbon-coated thin sections in a Jeol JXA-8600 electron microprobe using a Noran Voyager 4.1 automation system at the Geoanalítica USP Core Facility of the University of São Paulo (USP). The analyses of standards and unknown samples were performed according to the electron microprobe settings of Williams (1996Williams C.T. 1996. Analysis of rare earth minerals Jones A.P., Wall F., Williams C.T. (eds.) Rare earth minerals: chemistry, origin and ore deposits. Mineralogical Society Series 7, London, Chapman & Hall, p. 327-348.) (accelerating voltage of 25 kV and beam current of 100 nA) to properly quantify REE, HFSE, and other trace elements. The peak counting times were 10-20 s (F, Cl, Na, Si, K, Ca, Mn, Fe, Mg, Ti, and Al) and 40-60 s (La, Ce, Pr, Nd, Gd, Er, Yb, Y, Zr, Hf, Nb, Ta, U, Th, and Pb); the background counting times were half of the corresponding peak values. The Na and F contents were measured in the first minute of the analysis to prevent volatilization/migration due to the high probe current. A 30-µm beam diameter was also employed to avoid volatilization/migration. The small EGM grain size in the studied samples together with the large beam diameter precluded a core-to-rim characterization. A combination of well-characterized natural and synthetic standards was used. The data were processed using the PROZA procedure (Bastin et al. 1984Bastin G.F., Van Loo F.J.J., Heijligers H.J.M. 1984. Evaluation and use of gaussian Ф (ρz) curves in quantitative electron probe microanalysis: a new optimization. X-Ray Spectrometry , 13(2):91-97.). Special care was taken in the selection of the peak and background position to eliminate peak overlap. The detection limits were in the range of 0.01-0.03 wt%, except for F (up to 0.15 wt%).
After the removal of carbon coating from the thin sections, in situ trace-element analyses were performed on the same grain and as close as possible to the microprobe spot analysis using the laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) at the Geoanalítica-USP Facility of the USP. The analytical work utilized a Perkin Elmer Elan 6100 DRC ICP-MS instrument coupled with a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser (New Wave UP 213 AF) operating at a wavelength of 213 nm in a He+Ar atmosphere. Laser ablation was performed at 1.5 J/cm2 at a pulse rate of 10 Hz. Due to the small grain size, and to avoid mineral inclusions, a predetermined line raster of 120 µm with a 15-µm beam diameter at a 2-µm/s scan speed was used. The Glitter 4.4.2 software (Van Achterbergh et al. 2001Van Achterbergh E., Ryan C.G., Jackson S.E., Griffin W.L. 2001. Data reduction software for LA-ICP-MS: appendix : Silvester P.J. (ed.) Laser Ablation-ICP-Mass spectrometry in the Earth sciences: principles and applications . Mineralogical Association of Canada Short Course Series 29, Ottawa, Mineralogical Association of Canada, p. 239-243.) was used for data processing with National Institute of Standards and Technology (NIST) SRM 610 as the external standard and 42Ca as the internal standard using values for CaO from the electron microprobe analysis for the minerals. A linear adjustment was selected as the interpolation method for drift control and quantification. The relative errors (1σ) were in the range of 5-10% for most of the trace elements. Detection limits are usually between 0.1 and 2 ppm, except for Mg and Zn, with values up to 20 ppm. Whenever an element was analyzed with microprobe and LA-ICP-MS (e.g., Hf, Ta, Pb, Mg, and some REE), the more precise data from LA-ICP-MS were preferred.
EGM structural formulae were calculated according to Johnsen & Grice (1999Johnsen O., Grice J.D. 1999. The crystal chemistry of the eudialyte group. The Canadian Mineralogist ,37:865-891.) and Johnsen et al. (2001Johnsen O., Grice J.D., Gault R.A. 2001. The eudialyte group: a review. Geology of Greenland Survey Bulletin , 190:65-72.) based on 29 cations (sum of Si, Al, Zr, Ti, Hf, Nb, W and Ta) and constraining all Fe and Mn to be divalent.
The bulk-rock compositions of major and some trace elements were analyzed in a fused glass disc and pressed powder pellets using a Philips PW 2400 X-ray fluorescence spectrometer at the Geoanalítica-USP Facility of the USP using standard methods as described by Mori et al. (1999Mori P.E., Reeves S., Correia C.T., Haukka M. 1999. Development of a fused glass disc XRF facility and comparison with the pressed powder pellet technique at Instituto de Geociências, São Paulo University. Revista Brasileira de Geociências , 29:441-446.). Weight loss on ignition (LOI) was evaluated using standard gravimetric techniques. Trace elements and REE were analyzed in a Perkin Elmer Elan 6100 DRC ICP-MS at the Geoanalítica-USP Facility of the USP following the procedures delineated in Navarro et al. (2008Navarro M.S., Andrade S., Ulbrich H.H.G.J., Gomes C.B., Girardi V.A.V. 2008. The direct determination of rare earth elements in basaltic and related rocks using ICP-MS: testing the efficiency of microwave oven sample decomposition procedures. Geostandards and Geoanalytical Research , 32(2):167-180. DOI: 10.1111/j.1751-908X.2008.00840.x
https://doi.org/10.1111/j.1751-908X.2008...
).
RESULTS
Bulk-rock composition
Bulk-rock data for selected agpaitic dykes from Monte de Trigo are presented in Table 1. These rocks have SiO2 contents varying from 57.6 wt% to 59.9 wt% and Na2O+K2O from 13.2 wt% to 14.4 wt%. All dykes are peralkaline (molar (Na2O+K2O)/Al2O3 > 1) and contain EGMs, wöhlerite, låvenite, and/or hiortdahlite. Major compositional differences among the dykes are controlled by the amounts of mafic and accessory phases they contain. The least evolved agpaitic variety is EGM-free, aegirine-rich (~7 vol%), has low mg# (molar MgO/(MgO+FeOt) = 0.09), REE (267 ppm) and Zr (969 ppm) contents, and relatively high SiO2 (59.91 wt%) and Fe2O3 (5.38 wt%) contents. The EGM-free evolved variety has high REE contents (569 ppm), which are associated with their relatively high britholite modal content.
The EGM-bearing nepheline microsyenite dyke (peralkaline index = 1.08) has a sodic character (Na2O/K2O = 2.5), with the lowest K2O content and highest Na2O content among the dykes (4.4 wt% and 10.98 wt%, respectively). This dyke has an extremely low mg# (0.02), Ba (23 ppm), and Sr (18 ppm) contents and high Zr (2672 ppm), Nb (383 ppm), Rb (297 ppm), Y (51.3 ppm), and REE (381.2 ppm) contents (Table 1). The chondrite-normalized REE pattern exhibits light REE enrichment, with a LaN/YbN ratio of 9.9 and with a negative Eu/Eu* (C1 chondrite-normalized ratio of Eu/(Sm*Gd)1/2) anomaly of 0.20.
The melatheralite host rock has cumulate diopside and olivine crystals and exhibits high MgO (12.79 wt%), Fe2O3 (14.62 wt%), and CaO (15.17 wt%) contents, and low Na2O (0.91 wt%) and K2O (0.47 wt%) contents. Trace elements include high Cr (561 ppm), Ni (231 ppm), and Sr (669 ppm) contents. The REE content is low (∑REE = 115 ppm) and has a low light REE enrichment, with a LaN/YbN ratio of 8.6 and no europium anomaly (Eu/Eu* = 0.98).
EGM compositions
The major and trace element compositions of the EGMs from Monte de Trigo are listed in Table 2. The studied EGMs have high SiO2 (46.02-48.07 wt%) content with significant amounts of ZrO2 (11.11-12.11 wt%), Na2O (10.73-11.86 wt%), and CaO (10.76-12.51 wt%). In addition, they contain nearly equal concentrations of FeO (3.13-4.83 wt%) and MnO (3.01-4.52 wt%). Other major elements include Nb2O5 (1.28-3.09 wt%), REE2O3 (2.00-3.43 wt%), and Cl (1.67-1.85 wt%).
The most significant minor and trace element data include TiO2 (0.16-0.34 wt%), HfO2 (0.12-0.26 wt%), Ta2O5 (0.05-0.29 wt%), Y2O3 (0.37-0.86 wt%), PbO (0.09-0.22 wt%), K2O (0.23-0.50 wt%), F (0.13-0.31 wt%), Mg (60-3582 ppm), Sr (108-2,699 ppm), Zn (401-852 ppm), and W (216-882 ppm).
Compositions of other accessory phases
Wöhlerite (Na,Ca)8(Mn,Ca,Fe,Ti)4(Zr,Nb)4(Si2O7)4(O,F)8] and låvenite [Na4(Ca,Mn,Fe)8Zr2(Nb,Ti)2(Si2O7)4O4F2(F,O)2], minerals of the cuspidine group (Mellini & Merlino 1979Mellini M., Merlino S. 1979. Refinement of the crystal structure of Wöhlerite. Tschermaks Mineralogische und Petrographische Mitteilungen , 26(1):109-123. DOI: 10.1007/BF01081296
https://doi.org/10.1007/BF01081296...
, Mellini 1981Mellini M. 1981. Refinement of the crystal structure of låvenite. Tschermaks Mineralogische und Petrographische Mitteilungen , 28:99-112. DOI: 10.1007/BF01081548
https://doi.org/10.1007/BF01081548...
, Merlino & Perchiazzi 1988Merlino S., Perchiazzi N. 1988. Modular mineralogy in the cuspidine group of minerals. The Canadian Mineralogist ,26(4):933-943., Chakhmouradian et al. 2008Chakhmouradian A.R., Mitchell R.H., Burns P.C., Mikhailova Y., Reguir E.P. 2008. Marianoite, a new member of the cuspidine group from the Prairie Lake silicocarbonatite, Ontario. The Canadian Mineralogist ,46(4):1023-1032. DOI: 10.3749/canmin.46.4.1023
https://doi.org/10.3749/canmin.46.4.1023...
), are the major accessory phases that crystallize contemporaneously with EGMs in the studied dyke. Representative analyses of wöhlerite and låvenite are presented in Table 2. These phases have lower SiO2 and higher ZrO2 contents than EGMs. Wöhlerite has higher Nb2O5 and CaO contents than låvenite does, whereas the latter has high MnO, FeO, and Na2O contents. Both minerals have almost no LILE, but they are enriched to a variable degree in REE. Wöhlerite contains greater amounts of light REE than låvenite does. The LaN/YbN ratios of wöhlerite and låvenite are 2.05 and 0.12, respectively, which are significantly lower than the values for EGMs from the dyke center (4.8-8.0), EGMs from the dyke border (12.5-25.0) and the bulk-rock composition (9.9). The Eu/Eu* anomaly is somewhat similar to that observed in the EGMs and bulk-rock analysis. Låvenite also has high contents of Mg (3,819 ppm) and Zn (329 ppm).
DISCUSSION
EGM compositional variation and molecular components
According to the calculated structural formulae (Table 2), Si contents are sufficient to fill 25 tetrahedral positions, whereas the Zr (plus minor content of Hf) and Ca amounts fill the Z and M(1) positions, respectively. In the X site, Cl prevails over F.
The most extensive variation in the EGM composition from Monte de Trigo involves Fe and Mn at the M(2) site and Si and Nb at the M(3,4) site (Fig. 4). Both variations correspond to the solid solution between eudialyte and kentbrooksite components, recognized as the major substitution of the EGMs worldwide by Johnsen et al. (1998Johnsen O., Grice J.D., Gault R.A. 1998. Kentbrooksite from the Kangerdlugssuaq intrusion, East Greenland, a new Mn-REE-Nb-F end-member in a series within the eudialyte group: description and crystal structure. European Journal of Mineralogy , 10(2):207-219. DOI: 10.1127/ejm/10/2/0207
https://doi.org/10.1127/ejm/10/2/0207...
) and Johnsen & Grice (1999Johnsen O., Grice J.D. 1999. The crystal chemistry of the eudialyte group. The Canadian Mineralogist ,37:865-891.), although excluding the F and Cl contents. In fact, some analyses present Mn as dominant cation in M(2) site with the X site occupied by Cl, which probably is a mineral still not approved by the International Mineralogical Association. A slight excess of Zr from the Z site could be located with Nb and Si in the M(3,4) site, together with minor to trace contents of Ti, Ta, and W.
Plot of Nb vs . Si, Mn, Ca, ∑REEs+Y and Na (apfu ) for the EGMs from Monte de Trigo. Blue squares, the EGMs from the dyke border; open circles, the EGMs from the dyke center; black squares, theoretical end-members of the EGMs. Trend lines of the worldwide EGM compositions are compiled from Coulson & Chambers (1996Coulson I.A., Chambers A.D. 1996. Patterns of zonation in rare-earth-bearing minerals in nepheline syenites of the North Qôroq center, South Greenland. The Canadian Mineralogist ,34:1163-1178.), Gualda & Vlach (1996Gualda G.A.R., Vlach S.R.F. 1996. Eudialita-eucolita do maciço alcalino de Poços de Caldas, MG-SP: quimismo e correlação com o comportamento ótico. 39º Congresso Brasileiro de Geologia, Anais , v. 3, p. 34-36.), Coulson (1997Coulson I.A. 1997. Post-magmatic alteration in eudialyte from the North Qôroq centre, South Greenland. Mineralogical Magazine , 61:99-109. DOI: 10.1180/minmag.1997.061.404.10
https://doi.org/10.1180/minmag.1997.061.... ), Johnsen & Gault (1997Johnsen O., Gault R.A. 1997. Chemical variation in eudialyte. Neues Jahrbuch für Mineralogie-Abhandlungen , 171:215-237.), Olivio & Williams-Jones (1999Olivio G.R., Williams-Jones A.E. 1999. Hydrothermal REE-rich eudialyte from the Pilanesberg Complex, South Africa. The Canadian Mineralogist ,37(3):653-663.), Johnsen & Grice (1999Johnsen O., Grice J.D. 1999. The crystal chemistry of the eudialyte group. The Canadian Mineralogist ,37:865-891.), Mitchell & Liferovich (2006Mitchell R., Liferovich R. 2006. Subsolidus deuteric/hydrothermal alteration of eudialyte in lujavrite from the Pilansberg alkaline complex, South Africa. Lithos , 91(1-4):352-372. DOI: 10.1016/j.lithos.2006.03.025
https://doi.org/10.1016/j.lithos.2006.03... ), Marks et al. (2008Marks M.A.W., Schilling J., Coulson I.M., Wenzel T., Markl G. 2008. The Alkaline-Peralkaline Tamazeght Complex, High Atlas Mountains, Morocco: mineral chemistry and petrological constraints for derivation from a compositionally heterogeneous mantle source. Journal of Petrology , 49(6):1097-1131. DOI: 10.1093/petrology/egn019
https://doi.org/10.1093/petrology/egn019... ), Schilling et al. (2009Schilling J., Marks M., Wenzel T., Markl G. 2009. Reconstruction of magmatic to subsolidus processes in an agpaitic system using eudialyte textures and composition: a case study from Tamazeght, Morocco. The Canadian Mineralogist ,47(2):351-365. DOI: 10.3749/canmin.47.2.351
https://doi.org/10.3749/canmin.47.2.351... , 2011bSchilling J., Wu F.-Y., McCammon C., Wenzel T., Marks M.A.W., Pfaff K., Jacob D.E., Markl G. 2011b. The compositional variability of eudialyte-group minerals. Mineralogical Magazine , 75(1):87-115. DOI: 10.1180/minmag.2011.075.1.87
https://doi.org/10.1180/minmag.2011.075.... ), and Wu et al. (2010Wu F.-Y., Yang Y.-H., Marks M.A.W., Liu Z.-C., Zhou Q., Ge W.-C., Yang J.-S., Zhao Z.-S., Mitchell R.H., Markl G. 2010. In situ U-Pb, Nd and Hf isotopic analysis of eudialyte by LA-(MC)-ICP-MS. Chemical Geology , 273(1-2):8-34. DOI: http://dx.doi.org/10.1016/j.chemgeo.2010.02.007
http://dx.doi.org/10.1016/j.chemgeo.2010... ). Component abbreviations: eud, eudialyte; Mn-eud, manganoeudialyte; fekl, feklichevite; ktb, kentbrooksite; georg, georgbarsanovite; zirs, zirsilite-(Ce).
Other significant major element variations in the EGMs from Monte de Trigo occur at the N(1-5) site. Most of the 15 positions of the N(1-5) sites are filled with Na, which varies from 11.02 to 12.28 apfu. The remaining positions may include other elements, such as REE, Y, Ca, and Mn, probably at the N(4) site (Rastsvetaeva 2007Rastsvetaeva R.K. 2007. Structural mineralogy of the eudialyte group: a review. Crystallography Reports , 52(1):47-64. DOI: 10.1134/S1063774507010063
https://doi.org/10.1134/S106377450701006...
). The sum of the Fe and Mn contents (3.259 to 3.613 apfu ) exceeds the three available M(2) positions. This excess suggests that small amounts of the georgbarsanovite component are present in the solid solution, in which Mn is located at the N(4) site (Khomyakov et al. 2005Khomyakov A.P., Nechelyustov G.N., Ekimenkova I.A., Rastsvetaeva R.K. 2005. Georgbarsanovite, Na12(Mn,Sr,REE)3Ca6Fe2+
3Zr3NbSi25O76Cl2·H2O a mineral species of the eudialyte group: revalidation of barsanovite and the new name of the mineral. Zapiski Rossiiskogo Mineralogicheskogo Obshchetstva ,134:47-57., Rastsvetaeva 2007Rastsvetaeva R.K. 2007. Structural mineralogy of the eudialyte group: a review. Crystallography Reports , 52(1):47-64. DOI: 10.1134/S1063774507010063
https://doi.org/10.1134/S106377450701006...
). Similarly, the Ca content (6.129 to 7.098 apfu ) exceeds the required amount to fulfill the six positions of the M(1) site (Fig. 4), with the surplus Ca most likely located at the N(4) site, composing the feklichevite member (Pekov et al. 2001Pekov I.V., Ekimenkova I.A., Chukanov N.V., Rastsvetaeva R.K., Kononkova N.N., Pekova N.A., Zadov A.E. 2001. Feklichevite Na11Ca9(Fe3+,Fe2+)
2Zr3Nb[Si25O73](OH,H2O,Cl,O)5, a new mineral of the eudialyte group from Kovdor Massif, Kola peninsula. Zapiski Vserossijskogo Mineralogicheskogo Obshchestva , 130:55-65.).
The N(4) site also includes REE (0.381 to 0.673 apfu ) and Y (0.106 to 0.244 apfu ), which indicates the presence of a zirsilite-(Ce) component (Khomyakov et al. 2003Khomyakov A.P., Dusmatov V.D., Ferraris G., Gula A., Ivaldi G., Nechelyustov G.N. 2003. Zirsilite-(Ce), (Na,☐)12(Ce,Na)3Ca6Mn3Zr3Nb(Si25O73)(OH)3(CO3)·H2O, and carbokentbrooksite (Na,☐)12(Na,Ce)3Ca6Mn3Zr3Nb(Si25O73)(OH)3(CO3)·H2O: two new eudialyte-group minerals from the Dara-i-Pioz alkaline massif, Tajikistan. Zapiski Vserossijskogo Mineralogicheskogo Obshchestva ,132:40-51.). Light REE enrichment is observed in the C1 chondrite-normalized REE diagram (Fig. 5A), with LaN/SmN ratios ranging from 9.1 to 13.7 and GdN/LuN ratios ranging from 0.71 to 1.95. A clearly marked negative Eu/Eu* anomaly is present, with values varying from 0.17 to 0.23.
(A) C1 chondrite-normalized Ree diagram for EGMs. Chondrite values are from McDonough & Sun (1995McDonough W., Sun S.S. 1995. The composition of the Earth. Chemical Geology , 120(3-4):223-253. DOI: 10.1016/0009-2541(94)00140-4
https://doi.org/10.1016/0009-2541(94)001... ); (B) Bulk-rock-normalized multi-element diagram of the EGMs from Monte de Trigo. The bulk-rock values are from the EGM-bearing nepheline microsyenite dyke center sample (Table 1). Blue squares, the EGMs from the dyke border; open circles, the EGMs from the dyke center. The bulk-rock data from the dyke center (blue diamonds), låvenite (open triangle) and wöhlerite (black cross) are also plotted for comparison.
Thus, the EGMs from Monte de Trigo are best represented by a complex solid solution involving eudialyte, feklichevite, zirsilite-(Ce), georgbarsanovite, and kentbrooksite components (Fig. 4). Part of the Mn content of the EGMs may be responsible for the formation of minor quantities of the manganoeudialyte member (Nomura et al. 2010Nomura S.F., Atêncio D., Chukanov N.V., Rastsvetaeva R.K., Coutinho J.M.V., Karipidis T.K. 2010. Manganoeudialyte: a new mineral from Poços de Caldas, Minas Gerais, Brazil. Zapiski Rossiiskogo Mineralogicheskogo Obshchestva , 38:35-47.) rather than kentbrooksite to compensate for the Nb deficiency, assuming all of the Nb-bearing components are present. The EGMs from the dyke border are more enriched in the eudialyte component, whereas the EGMs from the dyke center are more enriched in the feklichevite, zirsilite-(Ce) and kentbrooksite components (Fig. 4).
The trace element contents normalized according to the bulk composition of the host dyke are shown in Figure 5B. The EGMs from the dyke border have significantly higher contents of Sr, Th, Zn, and Mg and significantly lower contents of Hf, Ta, and heavy REE than those from the dyke center. The low K, Rb, and Ba EGM/bulk-rock ratios suggest an incompatible behavior, i.e., they are not incorporated in the EGM structure. Thus, the andrianovite component, an EGM similar to kentbrooksite and zirsilite-(Ce), but with K located at the N(4) site (Khomyakov et al. 2008Khomyakov A.P., Nechelyustov G.N., Rastsvetaeva R.K., Rozenberg K.A. 2008. Andrianovite, Na12(K,Sr,Ce)3Ca6Mn3Zr3Nb(Si25O73)(O,H2O,OH)5, a new potassium-rich mineral species of the eudialyte group from the Khibiny alkaline Pluton, Kola Peninsula, Russia. Geology of Ore Deposits , 50(8):705-712. DOI: 10.1134/S1075701508080060
https://doi.org/10.1134/S107570150808006...
), is irrelevant in the composition of the EGMs from Monte de Trigo, despite the high K and Rb contents of the bulk rock (Table 1). This finding suggests that K and Rb prefer other minerals, such as alkali feldspar. The contents of Mg, Zn, Ga, Sr, Th, and U in EGMs are slightly higher than the ones in the host rock, which suggests that they are neutral to compatible in the EGM structure, whereas Pb is highly compatible, with EGM/bulk-rock ratios near 100, probably because the ionic radius of Pb (Shannon 1976Shannon R.D. 1976. Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides. Acta Crystallographica Section A , 32:751-767. DOI: 10.1107/S0567739476001551
https://doi.org/10.1107/S056773947600155...
) is similar to the size of the N(4) site (Johnsen & Grice 1999Johnsen O., Grice J.D. 1999. The crystal chemistry of the eudialyte group. The Canadian Mineralogist ,37:865-891.).
Petrologic implications
The EGMs from Monte de Trigo are distinguished by relatively high contents of Ca, moderate enrichment of Nb and REE, and a somewhat low content of Na when compared with the compositions from other localities worldwide (e.g., Deer et al. 1986Deer W.A., Howie R.A., Zussman J. 1986. Rock-forming minerals, volume 1B: Disilicates and Ring Silicates . Oxford, The Geological Society Publishing House, 629 p., Johnsen & Gault 1997Johnsen O., Gault R.A. 1997. Chemical variation in eudialyte. Neues Jahrbuch für Mineralogie-Abhandlungen , 171:215-237., Johnsen & Grice 1999Johnsen O., Grice J.D. 1999. The crystal chemistry of the eudialyte group. The Canadian Mineralogist ,37:865-891., Wu et al. 2010Wu F.-Y., Yang Y.-H., Marks M.A.W., Liu Z.-C., Zhou Q., Ge W.-C., Yang J.-S., Zhao Z.-S., Mitchell R.H., Markl G. 2010. In situ U-Pb, Nd and Hf isotopic analysis of eudialyte by LA-(MC)-ICP-MS. Chemical Geology , 273(1-2):8-34. DOI: http://dx.doi.org/10.1016/j.chemgeo.2010.02.007
http://dx.doi.org/10.1016/j.chemgeo.2010...
, Schilling et al. 2011bSchilling J., Wu F.-Y., McCammon C., Wenzel T., Marks M.A.W., Pfaff K., Jacob D.E., Markl G. 2011b. The compositional variability of eudialyte-group minerals. Mineralogical Magazine , 75(1):87-115. DOI: 10.1180/minmag.2011.075.1.87
https://doi.org/10.1180/minmag.2011.075....
). The EGMs from Monte de Trigo do have Na, Nb, Ca, and REE contents similar to those of the EGMs from Langesundsfjord and North Qôroq (Fig. 4) (Bollingberg et al. 1983Bollingberg H.J., Ure A.M., Sørensen I., Leonardsen E.S. 1983. Geochemistry of some eudialyte-eucolite troimens and a co-existing catapleiite from Langesund, Norway. Tschermaks Mineralogische und Petrographische Mitteilungen , 32:153-169., Coulson & Chambers 1996Coulson I.A., Chambers A.D. 1996. Patterns of zonation in rare-earth-bearing minerals in nepheline syenites of the North Qôroq center, South Greenland. The Canadian Mineralogist ,34:1163-1178., Coulson 1997Coulson I.A. 1997. Post-magmatic alteration in eudialyte from the North Qôroq centre, South Greenland. Mineralogical Magazine , 61:99-109. DOI: 10.1180/minmag.1997.061.404.10
https://doi.org/10.1180/minmag.1997.061....
, Wu et al. 2010Wu F.-Y., Yang Y.-H., Marks M.A.W., Liu Z.-C., Zhou Q., Ge W.-C., Yang J.-S., Zhao Z.-S., Mitchell R.H., Markl G. 2010. In situ U-Pb, Nd and Hf isotopic analysis of eudialyte by LA-(MC)-ICP-MS. Chemical Geology , 273(1-2):8-34. DOI: http://dx.doi.org/10.1016/j.chemgeo.2010.02.007
http://dx.doi.org/10.1016/j.chemgeo.2010...
).
The Na-poor and Ca-rich composition of the analyzed EGMs may be a consequence of transitional agpaitic magma composition. The accessory mineral assemblage from Monte de Trigo, as well as those from Langesundsfjord and North Qôroq, includes complex Na-Ca-Zr-F silicate minerals, such as wöhlerite and låvenite (Coulson 1997Coulson I.A. 1997. Post-magmatic alteration in eudialyte from the North Qôroq centre, South Greenland. Mineralogical Magazine , 61:99-109. DOI: 10.1180/minmag.1997.061.404.10
https://doi.org/10.1180/minmag.1997.061....
, Enrich et al. 2009Enrich G.E.R., Ruberti E., Gomes C.B. 2009. Geology and geochronology of Monte de Trigo Island alkaline suite, southeastern Brazil. Revista Brasileira de Geociências , 39(1):67-80., Andersen et al. 2010Andersen T., Erambert M., Larsen A.O., Selbekk R.S. 2010. Petrology of nepheline syenite pegmatites in the Oslo Rift, Norway: zirconium silicate mineral assemblages as indicators of alkalinity and volatile fugacity in mildly agpaitic magma. Journal of Petrology , 51(11):2303-2325. DOI: 10.1093/petrology/egq058
https://doi.org/10.1093/petrology/egq058...
), which is typical of transitional agpaitic rocks (Sørensen 1997Sørensen H. 1997. The agpaitic rocks, an overview. Mineralogical Magazine , 61(4):485-498., Andersen et al. 2010Andersen T., Erambert M., Larsen A.O., Selbekk R.S. 2010. Petrology of nepheline syenite pegmatites in the Oslo Rift, Norway: zirconium silicate mineral assemblages as indicators of alkalinity and volatile fugacity in mildly agpaitic magma. Journal of Petrology , 51(11):2303-2325. DOI: 10.1093/petrology/egq058
https://doi.org/10.1093/petrology/egq058...
, Marks et al. 2011Marks M.A.W., Hettmann K., Schilling J., Frost B.R., Markl G. 2011. The mineralogical diversity of alkaline igneous rocks: critical factors for the transition from miaskitic to agpaitic phase assemblages. Journal of Petrology , 52(3):439-455. DOI: 10.1093/petrology/egq086
https://doi.org/10.1093/petrology/egq086...
). This assemblage suggests that the miaskitic to agpaitic transition in the Monte de Trigo alkaline suite follows the increasing fluorine trend of Andersen et al. (2010Andersen T., Erambert M., Larsen A.O., Selbekk R.S. 2010. Petrology of nepheline syenite pegmatites in the Oslo Rift, Norway: zirconium silicate mineral assemblages as indicators of alkalinity and volatile fugacity in mildly agpaitic magma. Journal of Petrology , 51(11):2303-2325. DOI: 10.1093/petrology/egq058
https://doi.org/10.1093/petrology/egq058...
). The EGM crystallization along this fluorine trend, according to these authors, can occur if chlorine or HCl activity is sufficiently high. This seems to be the case for the EGMs from Monte de Trigo, as evidenced by their relatively high Cl content.
Most of the trace element contents of the EGMs from Monte de Trigo vary within the ranges of EGMs from other localities (Wu et al. 2010Wu F.-Y., Yang Y.-H., Marks M.A.W., Liu Z.-C., Zhou Q., Ge W.-C., Yang J.-S., Zhao Z.-S., Mitchell R.H., Markl G. 2010. In situ U-Pb, Nd and Hf isotopic analysis of eudialyte by LA-(MC)-ICP-MS. Chemical Geology , 273(1-2):8-34. DOI: http://dx.doi.org/10.1016/j.chemgeo.2010.02.007
http://dx.doi.org/10.1016/j.chemgeo.2010...
, Schilling et al. 2011bSchilling J., Wu F.-Y., McCammon C., Wenzel T., Marks M.A.W., Pfaff K., Jacob D.E., Markl G. 2011b. The compositional variability of eudialyte-group minerals. Mineralogical Magazine , 75(1):87-115. DOI: 10.1180/minmag.2011.075.1.87
https://doi.org/10.1180/minmag.2011.075....
), especially the HFSEs and REE. Major differences of the analyzed EGMs include low-Sr and Ba contents and a negative Eu/Eu* ratio (Fig. 6). These differences are also found in the bulk composition of the EGM-bearing nepheline microsyenite dyke (Table 1), which suggests that EGMs crystallized in an environment where Eu, Sr, and Ba were already depleted. This depletion could be assigned to previous extensive fractionation of plagioclase and/or alkali feldspar (e.g., Blundy & Wood 1991Blundy J.D., Wood B.J. 1991. Crystal-chemical controls on the partitioning of Sr and Ba between plagioclase feldspar, silicate melts, and hydrothermal solutions. Geochimica et Cosmochimica Acta , 55(1):193-209. DOI: 10.1016/0016-7037(91)90411-W
https://doi.org/10.1016/0016-7037(91)904...
, Bédard 2006Bédard J.H. 2006. Trace element partitioning in plagioclase feldspar. Geochimica et Cosmochimica Acta , 70(14):3717-3742. DOI: 10.1016/j.gca.2006.05.003
https://doi.org/10.1016/j.gca.2006.05.00...
, Brotzu et al. 2007Brotzu P., Melluso L., Bennio L., Gomes C.B., Lustrino M., Morbidelli L., Morra V., Ruberti E., Tassinari C., D'Antonio M. 2007. Petrogenesis of the Early Cenozoic potassic alkaline complex of Morro de São João, southeastern Brazil. Journal of South American Earth Science , 24(1):93-115. DOI: 10.1016/j.jsames.2007.02.006
https://doi.org/10.1016/j.jsames.2007.02...
, Henderson & Pierozynski 2012Henderson C.M.B., Pierozynski W.J. 2012. An experimental study of Sr, Ba and Rb partitioning between alkali feldspar and silicate liquid in the system nepheline-kalsilite-quartz at 0.1 GPa P(H2O): a revisitation and reassessment. Mineralogical Magazine , 76(1):157-190. DOI: 10.1180/minmag.2012.076.1.157
https://doi.org/10.1180/minmag.2012.076....
, Carvalho & Janasi 2012Carvalho B.B., Janasi V.A. 2012. Crystallization conditions and controls on trace element residence in the main minerals from the Pedra Branca syenite, Brazil: an electron microprobe and LA-ICPMS study. Lithos , 153(6):208-223.) from the parental melt, similar to the interpretation by Schilling et al. (2011bSchilling J., Wu F.-Y., McCammon C., Wenzel T., Marks M.A.W., Pfaff K., Jacob D.E., Markl G. 2011b. The compositional variability of eudialyte-group minerals. Mineralogical Magazine , 75(1):87-115. DOI: 10.1180/minmag.2011.075.1.87
https://doi.org/10.1180/minmag.2011.075....
) regarding the same features observed in the EGMs from Ilímaussaq and Mont Saint-Hilaire.
Plot of Nb vs . Si, Mn, Ca, ∑REE+Y and Na (apfu ) for the EGMs from Monte de Trigo. Trend lines of the worldwide EGM compositions are compiled from Gualda & Vlach (1996Gualda G.A.R., Vlach S.R.F. 1996. Eudialita-eucolita do maciço alcalino de Poços de Caldas, MG-SP: quimismo e correlação com o comportamento ótico. 39º Congresso Brasileiro de Geologia, Anais , v. 3, p. 34-36.), Johnsen & Gault (1997Johnsen O., Gault R.A. 1997. Chemical variation in eudialyte. Neues Jahrbuch für Mineralogie-Abhandlungen , 171:215-237.), Johnsen & Grice (1999Johnsen O., Grice J.D. 1999. The crystal chemistry of the eudialyte group. The Canadian Mineralogist ,37:865-891.), Marks et al. (2008Marks M.A.W., Schilling J., Coulson I.M., Wenzel T., Markl G. 2008. The Alkaline-Peralkaline Tamazeght Complex, High Atlas Mountains, Morocco: mineral chemistry and petrological constraints for derivation from a compositionally heterogeneous mantle source. Journal of Petrology , 49(6):1097-1131. DOI: 10.1093/petrology/egn019
https://doi.org/10.1093/petrology/egn019... ), Schilling et al. (2009Schilling J., Marks M., Wenzel T., Markl G. 2009. Reconstruction of magmatic to subsolidus processes in an agpaitic system using eudialyte textures and composition: a case study from Tamazeght, Morocco. The Canadian Mineralogist ,47(2):351-365. DOI: 10.3749/canmin.47.2.351
https://doi.org/10.3749/canmin.47.2.351... , 2011bSchilling J., Wu F.-Y., McCammon C., Wenzel T., Marks M.A.W., Pfaff K., Jacob D.E., Markl G. 2011b. The compositional variability of eudialyte-group minerals. Mineralogical Magazine , 75(1):87-115. DOI: 10.1180/minmag.2011.075.1.87
https://doi.org/10.1180/minmag.2011.075.... ), and Wu et al. (2010Wu F.-Y., Yang Y.-H., Marks M.A.W., Liu Z.-C., Zhou Q., Ge W.-C., Yang J.-S., Zhao Z.-S., Mitchell R.H., Markl G. 2010. In situ U-Pb, Nd and Hf isotopic analysis of eudialyte by LA-(MC)-ICP-MS. Chemical Geology , 273(1-2):8-34. DOI: http://dx.doi.org/10.1016/j.chemgeo.2010.02.007
http://dx.doi.org/10.1016/j.chemgeo.2010... ). Blue squares, the EGMs from the dyke border; open circles, the EGMs from the dyke center.
Extensive plagioclase fractionation is usually related to alkaline massifs with a basanite/alkali basalt parental melt, whereas it is absent for nephelinite parental magma (Marks et al. 2011Marks M.A.W., Hettmann K., Schilling J., Frost B.R., Markl G. 2011. The mineralogical diversity of alkaline igneous rocks: critical factors for the transition from miaskitic to agpaitic phase assemblages. Journal of Petrology , 52(3):439-455. DOI: 10.1093/petrology/egq086
https://doi.org/10.1093/petrology/egq086...
, Schilling et al. 2011aSchilling J., Marks M.A.W., Wenzel T., Vennemann T., Horváth L., Tarassoff P., Jacob D.E., Markl G. 2011a. The magmatic to hydrothermal evolution of the intrusive Mont Saint-Hilaire Complex: insights into the late-stage evolution of peralkaline rocks. Journal of Petrology , 52(11):2147-2185. DOI: 10.1093/petrology/egr042
https://doi.org/10.1093/petrology/egr042...
, 2011bSchilling J., Wu F.-Y., McCammon C., Wenzel T., Marks M.A.W., Pfaff K., Jacob D.E., Markl G. 2011b. The compositional variability of eudialyte-group minerals. Mineralogical Magazine , 75(1):87-115. DOI: 10.1180/minmag.2011.075.1.87
https://doi.org/10.1180/minmag.2011.075....
). Thus, EGMs that are crystallized from agpaitic residual liquids derived from basanite/alkali basalt and nephelinite parental magmas should present Sr-poor and Sr-rich trends, respectively. The compositional trends for EGMs from several occurrences are shown in the FeO-SrO-REE2O3 diagram (Fig 7). The FeO-rich corner characterizes the composition of early magmatic EGMs, as indicated by Schilling et al. (2011bSchilling J., Wu F.-Y., McCammon C., Wenzel T., Marks M.A.W., Pfaff K., Jacob D.E., Markl G. 2011b. The compositional variability of eudialyte-group minerals. Mineralogical Magazine , 75(1):87-115. DOI: 10.1180/minmag.2011.075.1.87
https://doi.org/10.1180/minmag.2011.075....
). Both REE- and Sr-rich end-members of EGMs are related to late-magmatic and/or post-magmatic hydrothermal fluids, as are, for example, the final compositions of the EGM trends from the Pilanesberg and Saint-Hilaire complexes (Olivio & Williams-Jones 1999Olivio G.R., Williams-Jones A.E. 1999. Hydrothermal REE-rich eudialyte from the Pilanesberg Complex, South Africa. The Canadian Mineralogist ,37(3):653-663., Mitchell & Liferovich 2006Mitchell R., Liferovich R. 2006. Subsolidus deuteric/hydrothermal alteration of eudialyte in lujavrite from the Pilansberg alkaline complex, South Africa. Lithos , 91(1-4):352-372. DOI: 10.1016/j.lithos.2006.03.025
https://doi.org/10.1016/j.lithos.2006.03...
, Grice & Gault 2006Grice J.D., Gault R.A. 2006. Johnsenite-(Ce): a new member of the eudialyte group from Mont Saint-Hilaire, Quebec, Canada. The Canadian Mineralogist ,44(1):105-115. DOI: 10.2113/gscanmin.44.1.105
https://doi.org/10.2113/gscanmin.44.1.10...
, Schilling et al. (2011bSchilling J., Wu F.-Y., McCammon C., Wenzel T., Marks M.A.W., Pfaff K., Jacob D.E., Markl G. 2011b. The compositional variability of eudialyte-group minerals. Mineralogical Magazine , 75(1):87-115. DOI: 10.1180/minmag.2011.075.1.87
https://doi.org/10.1180/minmag.2011.075....
). The Sr-poor EGM trends found at Saint-Hilaire and Ilímaussaq reflect their basanite/alkali basalt parental magma (Larsen & Sørensen 1987Larsen L.M., Sørensen H. 1987. The Ilímaussaq intrusion-progressive crystallization and formation of layering in an agpaitic magma Fitton J.G., Upton B.G.J. (eds.) Alkaline Igneous Rocks . Geological Society Special Publications, 30, London, Geological Society of London, p. 473-488., Bailey et al. 2001Bailey J.C., Gwozdz R., Rose-Hansen J., Sørensen H. 2001. Geochemical overview of the Ilímaussaq alkaline complex, South Greenland. Geology of Greenland Survey Bulletin ,190(100):35-53., Schilling et al. 2011aSchilling J., Marks M.A.W., Wenzel T., Vennemann T., Horváth L., Tarassoff P., Jacob D.E., Markl G. 2011a. The magmatic to hydrothermal evolution of the intrusive Mont Saint-Hilaire Complex: insights into the late-stage evolution of peralkaline rocks. Journal of Petrology , 52(11):2147-2185. DOI: 10.1093/petrology/egr042
https://doi.org/10.1093/petrology/egr042...
). Conversely, the Sr-rich EGM trends found at Poços de Caldas, Gardiner, Khibina and Lovozero could be linked to their nephelinite parental magma (Nielsen 1980Nielsen T.F.D. 1980. The petrology of a melilitolite, melteigite, carbonatite and syenite ring dike system, in the Gardiner complex, East Greenland. Lithos , 13(2):181-197. DOI: 10.1016/0024-4937(80)90019-5
https://doi.org/10.1016/0024-4937(80)900...
, Kramm & Kogarko 1994Kramm U., Kogarko L.N. 1994. Nd and Sr isotope signatures of the Khibina and Lovozero agpaitic centres, Kola Alkaline Province, Russia. Lithos , 32(3):225-242. DOI: 10.1016/0024-4937(94)90041-8
https://doi.org/10.1016/0024-4937(94)900...
, Sørensen 1997Sørensen H. 1997. The agpaitic rocks, an overview. Mineralogical Magazine , 61(4):485-498., Ulbrich et al. 2005Ulbrich H.H.G.J., Demaiffe D., Vlach S.R.F., Ulbrich M.N.C. 2005. Structure and origin of the Poços de Caldas alkaline massif, SE Brazil Comin-Chiaramonti P., Gomes C.B. (eds.) Mesozoic to Cenozoic alkaline magmatism in the Brazilian Platform . São Paulo, Edusp/FAPESP, p. 367-418., Kogarko et al. 2010Kogarko L.N., Lahaye Y., Brey G.P. 2010. Plume-related mantle source of super-large rare metal deposits from the Lovozero and Khibina massifs on the Kola Peninsula, Eastern part of Baltic Shield: Sr, Nd and Hf isotope systematics. Mineralogy and Petrology , 98(1):197-208. DOI: 10.1007/s00710-009-0066-1
https://doi.org/10.1007/s00710-009-0066-...
). The EGMs from Monte de Trigo have relative Fe and REE enrichment that, together with the EGM texture, agrees with its magmatic origin. The Sr-poor EGM trends found in Monte de Trigo reflect their basanite/alkali basalt parental magma. A mafic dyke with basanite composition has already been described in Monte de Trigo (Thompson et al. 1998Thompson R.N., Gibson S.A., Mitchell J.G., Dickin A.P., Leonardos O.H., Brod J.A., Greenwood J.C. 1998. Migrating Cretaceous-Eocene magmatism in the Serra do Mar Alkaline Province, SE Brasil: melts from the deflected Trindade Mantle Plume? Journal of Petrology , 39(8):1493-1526. DOI: 10.1093/petroj/39.8.1493
https://doi.org/10.1093/petroj/39.8.1493...
, Enrich et al. 2009Enrich G.E.R., Ruberti E., Gomes C.B. 2009. Geology and geochronology of Monte de Trigo Island alkaline suite, southeastern Brazil. Revista Brasileira de Geociências , 39(1):67-80.), and it probably represents the parental magma for this alkaline suite. Again, the EGMs from Monte de Trigo are plotted close to the north Qôroq and Langesundsfjord EGM data.
Ternary plot of FeO-SrO-REE2O3 for the EGMs from Monte de Trigo. Trend lines of the worldwide EGM compositions are compiled from Coulson & Chambers (1996Coulson I.A., Chambers A.D. 1996. Patterns of zonation in rare-earth-bearing minerals in nepheline syenites of the North Qôroq center, South Greenland. The Canadian Mineralogist ,34:1163-1178.), Gualda & Vlach (1996Gualda G.A.R., Vlach S.R.F. 1996. Eudialita-eucolita do maciço alcalino de Poços de Caldas, MG-SP: quimismo e correlação com o comportamento ótico. 39º Congresso Brasileiro de Geologia, Anais , v. 3, p. 34-36.), Coulson (1997Coulson I.A. 1997. Post-magmatic alteration in eudialyte from the North Qôroq centre, South Greenland. Mineralogical Magazine , 61:99-109. DOI: 10.1180/minmag.1997.061.404.10
https://doi.org/10.1180/minmag.1997.061.... ), Johnsen & Gault (1997Johnsen O., Gault R.A. 1997. Chemical variation in eudialyte. Neues Jahrbuch für Mineralogie-Abhandlungen , 171:215-237.), Olivio & Williams-Jones (1999Olivio G.R., Williams-Jones A.E. 1999. Hydrothermal REE-rich eudialyte from the Pilanesberg Complex, South Africa. The Canadian Mineralogist ,37(3):653-663.), Johnsen & Grice (1999Johnsen O., Grice J.D. 1999. The crystal chemistry of the eudialyte group. The Canadian Mineralogist ,37:865-891.), Mitchell & Liferovich (2006Mitchell R., Liferovich R. 2006. Subsolidus deuteric/hydrothermal alteration of eudialyte in lujavrite from the Pilansberg alkaline complex, South Africa. Lithos , 91(1-4):352-372. DOI: 10.1016/j.lithos.2006.03.025
https://doi.org/10.1016/j.lithos.2006.03... ), Marks et al. (2008Marks M.A.W., Schilling J., Coulson I.M., Wenzel T., Markl G. 2008. The Alkaline-Peralkaline Tamazeght Complex, High Atlas Mountains, Morocco: mineral chemistry and petrological constraints for derivation from a compositionally heterogeneous mantle source. Journal of Petrology , 49(6):1097-1131. DOI: 10.1093/petrology/egn019
https://doi.org/10.1093/petrology/egn019... ), Schilling et al. (2009Schilling J., Marks M., Wenzel T., Markl G. 2009. Reconstruction of magmatic to subsolidus processes in an agpaitic system using eudialyte textures and composition: a case study from Tamazeght, Morocco. The Canadian Mineralogist ,47(2):351-365. DOI: 10.3749/canmin.47.2.351
https://doi.org/10.3749/canmin.47.2.351... , 2011bSchilling J., Wu F.-Y., McCammon C., Wenzel T., Marks M.A.W., Pfaff K., Jacob D.E., Markl G. 2011b. The compositional variability of eudialyte-group minerals. Mineralogical Magazine , 75(1):87-115. DOI: 10.1180/minmag.2011.075.1.87
https://doi.org/10.1180/minmag.2011.075.... ), and Wu et al. (2010Wu F.-Y., Yang Y.-H., Marks M.A.W., Liu Z.-C., Zhou Q., Ge W.-C., Yang J.-S., Zhao Z.-S., Mitchell R.H., Markl G. 2010. In situ U-Pb, Nd and Hf isotopic analysis of eudialyte by LA-(MC)-ICP-MS. Chemical Geology , 273(1-2):8-34. DOI: http://dx.doi.org/10.1016/j.chemgeo.2010.02.007
http://dx.doi.org/10.1016/j.chemgeo.2010... ). Blue squares, the EGMs from the dyke border; open circles, the EGMs from the dyke center.
Some additional considerations about the compositional differences between the EGMs from the dyke border in relation to those from the center also could be made. The EGMs from the dyke border have the highest Mg (up to 3,582 ppm) and Zn (up to 852 ppm) contents of the worldwide EGMs (up to 1,000 ppm and 200 ppm for Mg and Zn, respectively; Deer et al. 1986Deer W.A., Howie R.A., Zussman J. 1986. Rock-forming minerals, volume 1B: Disilicates and Ring Silicates . Oxford, The Geological Society Publishing House, 629 p., Gualda & Vlach 1996Gualda G.A.R., Vlach S.R.F. 1996. Eudialita-eucolita do maciço alcalino de Poços de Caldas, MG-SP: quimismo e correlação com o comportamento ótico. 39º Congresso Brasileiro de Geologia, Anais , v. 3, p. 34-36., Johnsen et al. 1998Johnsen O., Grice J.D., Gault R.A. 1998. Kentbrooksite from the Kangerdlugssuaq intrusion, East Greenland, a new Mn-REE-Nb-F end-member in a series within the eudialyte group: description and crystal structure. European Journal of Mineralogy , 10(2):207-219. DOI: 10.1127/ejm/10/2/0207
https://doi.org/10.1127/ejm/10/2/0207...
, Johnsen & Grice 1999Johnsen O., Grice J.D. 1999. The crystal chemistry of the eudialyte group. The Canadian Mineralogist ,37:865-891., Ridolfi et al. 2003Ridolfi F., Renzulli A., Santi P., Upton B.G.J. 2003. Evolutionary stages of crystallization of weakly peralkaline syenites: evidence from ejecta in the plinian deposits of Agua de Pau volcano (São Miguel, Azores Islands). Mineralogical Magazine , 67(4):749-767. DOI: 10.1180/0026461036740131
https://doi.org/10.1180/0026461036740131...
, Bulakh & Petrov 2004Bulakh A.G., Petrov T.G. 2004. Chemical variability of eudialyte-group minerals and their sorting. Neues Jahrbuch für Mineralogie Monatshefte , 2004:127-144. DOI: 10.1127/0028-3649/2004/2004-0127
https://doi.org/10.1127/0028-3649/2004/2...
, Marks et al. 2008Marks M.A.W., Schilling J., Coulson I.M., Wenzel T., Markl G. 2008. The Alkaline-Peralkaline Tamazeght Complex, High Atlas Mountains, Morocco: mineral chemistry and petrological constraints for derivation from a compositionally heterogeneous mantle source. Journal of Petrology , 49(6):1097-1131. DOI: 10.1093/petrology/egn019
https://doi.org/10.1093/petrology/egn019...
, Wu et al. 2010Wu F.-Y., Yang Y.-H., Marks M.A.W., Liu Z.-C., Zhou Q., Ge W.-C., Yang J.-S., Zhao Z.-S., Mitchell R.H., Markl G. 2010. In situ U-Pb, Nd and Hf isotopic analysis of eudialyte by LA-(MC)-ICP-MS. Chemical Geology , 273(1-2):8-34. DOI: http://dx.doi.org/10.1016/j.chemgeo.2010.02.007
http://dx.doi.org/10.1016/j.chemgeo.2010...
, Schilling et al. 2011bSchilling J., Wu F.-Y., McCammon C., Wenzel T., Marks M.A.W., Pfaff K., Jacob D.E., Markl G. 2011b. The compositional variability of eudialyte-group minerals. Mineralogical Magazine , 75(1):87-115. DOI: 10.1180/minmag.2011.075.1.87
https://doi.org/10.1180/minmag.2011.075....
). Such high Mg and Zn contents, associated to relatively high Fe and Sr in these EGMs, could be related to the incorporation and reaction of the melatheralite xenoliths, as these elements are more abundant in the melatheralite (Table 1). The local-scale reaction due to the diffusive exchange between the melatheralite and the agpaitic magma at dyke border are suggested by the presence of corroded xenoliths (Fig. 1C), large mafic aggregates (Fig. 3B) and metasomatic granofels (Fig. 3A), and by the increase in modal mafic mineral content, up to 25% in volume. In addition, låvenite from the dyke border has higher Mg and Zn contents than wöhlerite from the dyke center (Table 2).
Other difference in EGM composition is related to the lower heavy REE contents of the EGMs at the dyke border than at the dyke center (Fig. 5). This seems to be a consequence of the crystallization of låvenite rather than of wöhlerite. Our data show that låvenite preferentially incorporates the heavy REE, whereas wöhlerite incorporates both the light and heavy REE (Fig. 5). The låvenite concomitant crystallization leads to a concurrence in the heavy REE partitioning between EGMs and låvenite.
CONCLUSIONS
The studied EGMs from Monte de Trigo reveal characteristics of their crystallization environment, i.e., magma composition and concomitant crystallizing phases. The EGMs are characterized by moderate variations in Fe and Mn at the M(2) site and Si and Nb at the M(3,4) site, which are recognized as the major substitution of EGMs worldwide. The relatively Na-poor, Ca-rich EGM compositions seem to be related to the Monte de Trigo transitional agpaitic rocks association, which contain wöhlerite and låvenite, and thus follow an agpaitic fluorine-rich trend. The low-Ba, Sr, and Eu contents are related to previous plagioclase fractionation during magmatic evolution and support the interpretation of a basanite parental magma for the suite. The incorporation and reaction of melatheralite xenoliths into the agpaitic magma could lead to higher Fe, Sr, Mg, and Zn contents in the EGMs found near the dyke border. Finally, the relative depletion of heavy REE in the EGMs from the dyke border seems to be related to the presence of låvenite, which strongly partitions heavy REE.
Acknowledgments
The authors are grateful to Research Support Foundation of the State of Sao Paulo (FAPESP) (GERE, Processes 00/12576-4 and 2010/20476-1; CBG, Process 2013/18073-4; ER, Process 2012/06082-6) for financial support. The authors also thank Sandra Andrade and Marcos Mansueto for their assistance during the analytical work. Contributions by anonymous reviewers have significantly improved the manuscript.
REFERENCES
- Almeida F.F.M. 1983. Relações tectônicas das rochas alcalinas mesozóicas da região meridional da plataforma sul-americana. Revista Brasileira de Geociências , 13(3):39-158.
- Andersen T., Erambert M., Larsen A.O., Selbekk R.S. 2010. Petrology of nepheline syenite pegmatites in the Oslo Rift, Norway: zirconium silicate mineral assemblages as indicators of alkalinity and volatile fugacity in mildly agpaitic magma. Journal of Petrology , 51(11):2303-2325. DOI: 10.1093/petrology/egq058
» https://doi.org/10.1093/petrology/egq058 - Azzone R.G., Ruberti E., Enrich G.E.R., Gomes C.B. 2009. Geologia e geocronologia do maciço alcalino máfico-ultramáfico Ponte Nova (SP-MG). Geologia USP Série Científica, 9(2):23-46. DOI: http://dx.doi.org/10.5327/z1519-874x2009000200002
» http://dx.doi.org/10.5327/z1519-874x2009000200002 - Bailey J.C., Gwozdz R., Rose-Hansen J., Sørensen H. 2001. Geochemical overview of the Ilímaussaq alkaline complex, South Greenland. Geology of Greenland Survey Bulletin ,190(100):35-53.
- Bastin G.F., Van Loo F.J.J., Heijligers H.J.M. 1984. Evaluation and use of gaussian Ф (ρz) curves in quantitative electron probe microanalysis: a new optimization. X-Ray Spectrometry , 13(2):91-97.
- Bédard J.H. 2006. Trace element partitioning in plagioclase feldspar. Geochimica et Cosmochimica Acta , 70(14):3717-3742. DOI: 10.1016/j.gca.2006.05.003
» https://doi.org/10.1016/j.gca.2006.05.003 - Blundy J.D., Wood B.J. 1991. Crystal-chemical controls on the partitioning of Sr and Ba between plagioclase feldspar, silicate melts, and hydrothermal solutions. Geochimica et Cosmochimica Acta , 55(1):193-209. DOI: 10.1016/0016-7037(91)90411-W
» https://doi.org/10.1016/0016-7037(91)90411-W - Bollingberg H.J., Ure A.M., Sørensen I., Leonardsen E.S. 1983. Geochemistry of some eudialyte-eucolite troimens and a co-existing catapleiite from Langesund, Norway. Tschermaks Mineralogische und Petrographische Mitteilungen , 32:153-169.
- Brotzu P., Barbieri M., Beccaluva L., Garbarino C., Gomes C.B., Macciotta G., Melluso L., Morbidelli L., Ruberti E., Sígolo J.B., Traversa G. 1992. Petrology and geochemistry of the Passa Quatro alkaline complex, Southeastern Brazil. Journal of South American Earth Science , 6(4):237-252. DOI: 10.1016/0895-9811(92)90044-Y
» https://doi.org/10.1016/0895-9811(92)90044-Y - Brotzu P., Gomes C.B., Melluso L., Morbidelli L., Morra V., Ruberti E. 1997. Petrogenesis of coexisting SiO2-undersaturated to SiO2-oversaturated felsic igneous rocks: The alkaline complex of Itatiaia, southeastern Brazil. Lithos , 40(2-4):133-156. DOI: 10.1016/S0024-4937(97)00007-8
» https://doi.org/10.1016/S0024-4937(97)00007-8 - Brotzu P., Melluso L., Bennio L., Gomes C.B., Lustrino M., Morbidelli L., Morra V., Ruberti E., Tassinari C., D'Antonio M. 2007. Petrogenesis of the Early Cenozoic potassic alkaline complex of Morro de São João, southeastern Brazil. Journal of South American Earth Science , 24(1):93-115. DOI: 10.1016/j.jsames.2007.02.006
» https://doi.org/10.1016/j.jsames.2007.02.006 - Brotzu P., Melluso L., D'Amelio F., Lustrino M. 2005. Potassic dykes and intrusions of the Serra do Mar Igneous Province (SE Brazil) Comin-Chiaramonti P., Gomes C.B. (eds.) Mesozoic to Cenozoic alkaline magmatism in the Brazilian Platform . São Paulo, Edusp/FAPESP, p. 443-472.
- Bulakh A.G., Petrov T.G. 2004. Chemical variability of eudialyte-group minerals and their sorting. Neues Jahrbuch für Mineralogie Monatshefte , 2004:127-144. DOI: 10.1127/0028-3649/2004/2004-0127
» https://doi.org/10.1127/0028-3649/2004/2004-0127 - Carbonin S., Liziero F., Fuso C. 2005. Mineral chemistry of accessory minerals in alkaline complexes from the Alto Paraguay Province Comin-Chiaramonti P., Gomes C.B. (eds.) Mesozoic to Cenozoic alkaline magmatism in the Brazilian Platform . São Paulo, Edusp/FAPESP, p. 149-158.
- Carvalho B.B., Janasi V.A. 2012. Crystallization conditions and controls on trace element residence in the main minerals from the Pedra Branca syenite, Brazil: an electron microprobe and LA-ICPMS study. Lithos , 153(6):208-223.
- Chakhmouradian A.R., Mitchell R.H., Burns P.C., Mikhailova Y., Reguir E.P. 2008. Marianoite, a new member of the cuspidine group from the Prairie Lake silicocarbonatite, Ontario. The Canadian Mineralogist ,46(4):1023-1032. DOI: 10.3749/canmin.46.4.1023
» https://doi.org/10.3749/canmin.46.4.1023 - Chukanov N.V., Rastsvetaeva R.K., Rozenberg K.A., Aksenov S.M., Pekov I.V., Belakovskiy D.I., Kristiansen R. 2015. Ilyukhinite, IMA 2015-065. CNMNC Newsletter No. 28, December 2015, page 1860; Mineralogical Magazine , 79(6):1859-1864. DOI: 10.1180/minmag.2015.079.7.18
» https://doi.org/10.1180/minmag.2015.079.7.18 - Comin-Chiaramonti P., Gomes C.B. 2005. Mesozoic to Cenozoic alkaline magmatism in the Brazilian Platform . São Paulo, Edusp/FAPESP, 752 p.
- Coulson I.A. 1997. Post-magmatic alteration in eudialyte from the North Qôroq centre, South Greenland. Mineralogical Magazine , 61:99-109. DOI: 10.1180/minmag.1997.061.404.10
» https://doi.org/10.1180/minmag.1997.061.404.10 - Coulson I.A., Chambers A.D. 1996. Patterns of zonation in rare-earth-bearing minerals in nepheline syenites of the North Qôroq center, South Greenland. The Canadian Mineralogist ,34:1163-1178.
- Deer W.A., Howie R.A., Zussman J. 1986. Rock-forming minerals, volume 1B: Disilicates and Ring Silicates . Oxford, The Geological Society Publishing House, 629 p.
- Enrich G.E.R., Azzone R.G., Ruberti E., Gomes C.B., Comin-Chiaramonti P. 2005. Itatiaia, Passa Quatro and São Sebastião Island, the major alkaline syenitic complexes from the Serra do Mar region Comin-Chiaramonti P., Gomes C.B. (eds.) Mesozoic to Cenozoic alkaline magmatism in the Brazilian Platform . São Paulo, Edusp/FAPESP, p. 419-442.
- Enrich G.E.R., Ruberti E., Gomes C.B. 2009. Geology and geochronology of Monte de Trigo Island alkaline suite, southeastern Brazil. Revista Brasileira de Geociências , 39(1):67-80.
- Gomes C.B., Laurenzi M.A., Censi P., De Min A., Velázquez V.F., Comin-Chiaramonti P. 1996. Alkaline magmatism from northern Paraguay (Alto Paraguay): a Permo-Triassic province : Comin-Chiaramonti P., Gomes C.B. (eds.) Alkaline Magmatism in Central-Eastern Paraguay. Relationships with Coeval Magmatism in Brazil . São Paulo, Edusp/Fapesp, p. 223-230.
- Grice J.D., Gault R.A. 2006. Johnsenite-(Ce): a new member of the eudialyte group from Mont Saint-Hilaire, Quebec, Canada. The Canadian Mineralogist ,44(1):105-115. DOI: 10.2113/gscanmin.44.1.105
» https://doi.org/10.2113/gscanmin.44.1.105 - Gualda G.A.R., Vlach S.R.F. 1996. Eudialita-eucolita do maciço alcalino de Poços de Caldas, MG-SP: quimismo e correlação com o comportamento ótico. 39º Congresso Brasileiro de Geologia, Anais , v. 3, p. 34-36.
- Henderson C.M.B., Pierozynski W.J. 2012. An experimental study of Sr, Ba and Rb partitioning between alkali feldspar and silicate liquid in the system nepheline-kalsilite-quartz at 0.1 GPa P(H2O): a revisitation and reassessment. Mineralogical Magazine , 76(1):157-190. DOI: 10.1180/minmag.2012.076.1.157
» https://doi.org/10.1180/minmag.2012.076.1.157 - Johnsen O., Gault R.A. 1997. Chemical variation in eudialyte. Neues Jahrbuch für Mineralogie-Abhandlungen , 171:215-237.
- Johnsen O., Grice J.D. 1999. The crystal chemistry of the eudialyte group. The Canadian Mineralogist ,37:865-891.
- Johnsen O., Ferraris G., Gault R.A., Grice J.D., Kampf A.R., Pekov I.V. 2003. The nomenclature of eudialyte-group minerals. The Canadian Mineralogist ,41:785-794. DOI: 10.2113/gscanmin.41.3.785
» https://doi.org/10.2113/gscanmin.41.3.785 - Johnsen O., Grice J.D., Gault R.A. 1998. Kentbrooksite from the Kangerdlugssuaq intrusion, East Greenland, a new Mn-REE-Nb-F end-member in a series within the eudialyte group: description and crystal structure. European Journal of Mineralogy , 10(2):207-219. DOI: 10.1127/ejm/10/2/0207
» https://doi.org/10.1127/ejm/10/2/0207 - Johnsen O., Grice J.D., Gault R.A. 2001. The eudialyte group: a review. Geology of Greenland Survey Bulletin , 190:65-72.
- Khomyakov A.P. 1995. Mineralogy of hiperagpaitic rocks . Oxford, Oxford Scientific Publications, Clarendon Press, 223 p.
- Khomyakov A.P., Dusmatov V.D., Ferraris G., Gula A., Ivaldi G., Nechelyustov G.N. 2003. Zirsilite-(Ce), (Na,☐)12(Ce,Na)3Ca6Mn3Zr3Nb(Si25O73)(OH)3(CO3)·H2O, and carbokentbrooksite (Na,☐)12(Na,Ce)3Ca6Mn3Zr3Nb(Si25O73)(OH)3(CO3)·H2O: two new eudialyte-group minerals from the Dara-i-Pioz alkaline massif, Tajikistan. Zapiski Vserossijskogo Mineralogicheskogo Obshchestva ,132:40-51.
- Khomyakov A.P., Nechelyustov G.N., Ekimenkova I.A., Rastsvetaeva R.K. 2005. Georgbarsanovite, Na12(Mn,Sr,REE)3Ca6Fe2+ 3Zr3NbSi25O76Cl2·H2O a mineral species of the eudialyte group: revalidation of barsanovite and the new name of the mineral. Zapiski Rossiiskogo Mineralogicheskogo Obshchetstva ,134:47-57.
- Khomyakov A.P., Nechelyustov G.N., Rastsvetaeva R.K., Rozenberg K.A. 2008. Andrianovite, Na12(K,Sr,Ce)3Ca6Mn3Zr3Nb(Si25O73)(O,H2O,OH)5, a new potassium-rich mineral species of the eudialyte group from the Khibiny alkaline Pluton, Kola Peninsula, Russia. Geology of Ore Deposits , 50(8):705-712. DOI: 10.1134/S1075701508080060
» https://doi.org/10.1134/S1075701508080060 - Kogarko L.N., Lahaye Y., Brey G.P. 2010. Plume-related mantle source of super-large rare metal deposits from the Lovozero and Khibina massifs on the Kola Peninsula, Eastern part of Baltic Shield: Sr, Nd and Hf isotope systematics. Mineralogy and Petrology , 98(1):197-208. DOI: 10.1007/s00710-009-0066-1
» https://doi.org/10.1007/s00710-009-0066-1 - Kramm U., Kogarko L.N. 1994. Nd and Sr isotope signatures of the Khibina and Lovozero agpaitic centres, Kola Alkaline Province, Russia. Lithos , 32(3):225-242. DOI: 10.1016/0024-4937(94)90041-8
» https://doi.org/10.1016/0024-4937(94)90041-8 - Larsen L.M., Sørensen H. 1987. The Ilímaussaq intrusion-progressive crystallization and formation of layering in an agpaitic magma Fitton J.G., Upton B.G.J. (eds.) Alkaline Igneous Rocks . Geological Society Special Publications, 30, London, Geological Society of London, p. 473-488.
- Le Maitre R.W. (Ed.) 2002. Igneous rocks: a classification of igneous rocks and glossary of terms.Cambridge, Cambridge University Press, 236 p.
- Marks M.A.W., Hettmann K., Schilling J., Frost B.R., Markl G. 2011. The mineralogical diversity of alkaline igneous rocks: critical factors for the transition from miaskitic to agpaitic phase assemblages. Journal of Petrology , 52(3):439-455. DOI: 10.1093/petrology/egq086
» https://doi.org/10.1093/petrology/egq086 - Marks M.A.W., Schilling J., Coulson I.M., Wenzel T., Markl G. 2008. The Alkaline-Peralkaline Tamazeght Complex, High Atlas Mountains, Morocco: mineral chemistry and petrological constraints for derivation from a compositionally heterogeneous mantle source. Journal of Petrology , 49(6):1097-1131. DOI: 10.1093/petrology/egn019
» https://doi.org/10.1093/petrology/egn019 - McDonough W., Sun S.S. 1995. The composition of the Earth. Chemical Geology , 120(3-4):223-253. DOI: 10.1016/0009-2541(94)00140-4
» https://doi.org/10.1016/0009-2541(94)00140-4 - Mellini M. 1981. Refinement of the crystal structure of låvenite. Tschermaks Mineralogische und Petrographische Mitteilungen , 28:99-112. DOI: 10.1007/BF01081548
» https://doi.org/10.1007/BF01081548 - Mellini M., Merlino S. 1979. Refinement of the crystal structure of Wöhlerite. Tschermaks Mineralogische und Petrographische Mitteilungen , 26(1):109-123. DOI: 10.1007/BF01081296
» https://doi.org/10.1007/BF01081296 - Merlino S., Perchiazzi N. 1988. Modular mineralogy in the cuspidine group of minerals. The Canadian Mineralogist ,26(4):933-943.
- Mitchell R., Liferovich R. 2006. Subsolidus deuteric/hydrothermal alteration of eudialyte in lujavrite from the Pilansberg alkaline complex, South Africa. Lithos , 91(1-4):352-372. DOI: 10.1016/j.lithos.2006.03.025
» https://doi.org/10.1016/j.lithos.2006.03.025 - Mitchell R.H., Chakrabarty A. 2012. Paragenesis and decomposition assemblage of a Mn-rich eudialyte from the Sushina peralkaline nepheline syenite gneiss, Paschim Banga, India. Lithos , 152:218-226. DOI: 10.1016/j.lithos.2012.02.003
» https://doi.org/10.1016/j.lithos.2012.02.003 - Morbidelli L., Gomes C.B., Beccaluva L., Brotzu P., Conte A.M., Ruberti E., Traversa G. 1995. Mineralogical, petrological and geochemical aspects of alkaline and alkaline-carbonatite associations from Brazil. Earth-Science Reviews , 39(3):135-168. DOI: 10.1016/0012-8252(95)00031-3
» https://doi.org/10.1016/0012-8252(95)00031-3 - Mori P.E., Reeves S., Correia C.T., Haukka M. 1999. Development of a fused glass disc XRF facility and comparison with the pressed powder pellet technique at Instituto de Geociências, São Paulo University. Revista Brasileira de Geociências , 29:441-446.
- Navarro M.S., Andrade S., Ulbrich H.H.G.J., Gomes C.B., Girardi V.A.V. 2008. The direct determination of rare earth elements in basaltic and related rocks using ICP-MS: testing the efficiency of microwave oven sample decomposition procedures. Geostandards and Geoanalytical Research , 32(2):167-180. DOI: 10.1111/j.1751-908X.2008.00840.x
» https://doi.org/10.1111/j.1751-908X.2008.00840.x - Nielsen T.F.D. 1980. The petrology of a melilitolite, melteigite, carbonatite and syenite ring dike system, in the Gardiner complex, East Greenland. Lithos , 13(2):181-197. DOI: 10.1016/0024-4937(80)90019-5
» https://doi.org/10.1016/0024-4937(80)90019-5 - Nomura S.F., Atêncio D., Chukanov N.V., Rastsvetaeva R.K., Coutinho J.M.V., Karipidis T.K. 2010. Manganoeudialyte: a new mineral from Poços de Caldas, Minas Gerais, Brazil. Zapiski Rossiiskogo Mineralogicheskogo Obshchestva , 38:35-47.
- Olivio G.R., Williams-Jones A.E. 1999. Hydrothermal REE-rich eudialyte from the Pilanesberg Complex, South Africa. The Canadian Mineralogist ,37(3):653-663.
- Peate D.W. 1997. The Paraná-Etendeka Province Mahoney J.J., Coffin M.F. (eds.) Large Igneous Provinces . Geophysical Monograph 100. Washington, American Geophysical Union, p. 217-245.
- Pekov I.V., Ekimenkova I.A., Chukanov N.V., Rastsvetaeva R.K., Kononkova N.N., Pekova N.A., Zadov A.E. 2001. Feklichevite Na11Ca9(Fe3+,Fe2+) 2Zr3Nb[Si25O73](OH,H2O,Cl,O)5, a new mineral of the eudialyte group from Kovdor Massif, Kola peninsula. Zapiski Vserossijskogo Mineralogicheskogo Obshchestva , 130:55-65.
- Rastsvetaeva R.K. 2007. Structural mineralogy of the eudialyte group: a review. Crystallography Reports , 52(1):47-64. DOI: 10.1134/S1063774507010063
» https://doi.org/10.1134/S1063774507010063 - Rastsvetaeva R.K., Chukanov N.V. 2012. Classification of eudialyte-group minerals. Geology of Ore Deposits , 54(7):487-497. DOI: 10.1134/S1075701512070069
» https://doi.org/10.1134/S1075701512070069 - Riccomini C., Velázquez V.F., Gomes C.B. 2005. Tectonic controls of the Mesozoic and Cenozoic alkaline magmatism in Central-Southeastern Brazilian Platform Comin-Chiaramonti P., Gomes C.B. (eds.) Mesozoic to Cenozoic alkaline magmatism in the Brazilian Platform . São Paulo, Edusp/FAPESP, p. 31-55.
- Ridolfi F., Renzulli A., Macdonald R., Upton B.G.J. 2006. Peralkaline syenite autoliths from Kilombe volcano, Kenya Rift Valley: evidence for subvolcanic interaction with carbonatitic fluids. Lithos , 91(1-4):373-392. DOI: 10.1016/j.lithos.2006.03.026
» https://doi.org/10.1016/j.lithos.2006.03.026 - Ridolfi F., Renzulli A., Santi P., Upton B.G.J. 2003. Evolutionary stages of crystallization of weakly peralkaline syenites: evidence from ejecta in the plinian deposits of Agua de Pau volcano (São Miguel, Azores Islands). Mineralogical Magazine , 67(4):749-767. DOI: 10.1180/0026461036740131
» https://doi.org/10.1180/0026461036740131 - Schilling J., Marks M., Wenzel T., Markl G. 2009. Reconstruction of magmatic to subsolidus processes in an agpaitic system using eudialyte textures and composition: a case study from Tamazeght, Morocco. The Canadian Mineralogist ,47(2):351-365. DOI: 10.3749/canmin.47.2.351
» https://doi.org/10.3749/canmin.47.2.351 - Schilling J., Marks M.A.W., Wenzel T., Vennemann T., Horváth L., Tarassoff P., Jacob D.E., Markl G. 2011a. The magmatic to hydrothermal evolution of the intrusive Mont Saint-Hilaire Complex: insights into the late-stage evolution of peralkaline rocks. Journal of Petrology , 52(11):2147-2185. DOI: 10.1093/petrology/egr042
» https://doi.org/10.1093/petrology/egr042 - Schilling J., Wu F.-Y., McCammon C., Wenzel T., Marks M.A.W., Pfaff K., Jacob D.E., Markl G. 2011b. The compositional variability of eudialyte-group minerals. Mineralogical Magazine , 75(1):87-115. DOI: 10.1180/minmag.2011.075.1.87
» https://doi.org/10.1180/minmag.2011.075.1.87 - Shannon R.D. 1976. Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides. Acta Crystallographica Section A , 32:751-767. DOI: 10.1107/S0567739476001551
» https://doi.org/10.1107/S0567739476001551 - Sørensen H. 1997. The agpaitic rocks, an overview. Mineralogical Magazine , 61(4):485-498.
- Stromeyer F. 1819. Summary of meeting 16 December 1819. Göttingische gelehrte Anzeigen , 3:1993-2000.
- Thompson R.N., Gibson S.A., Mitchell J.G., Dickin A.P., Leonardos O.H., Brod J.A., Greenwood J.C. 1998. Migrating Cretaceous-Eocene magmatism in the Serra do Mar Alkaline Province, SE Brasil: melts from the deflected Trindade Mantle Plume? Journal of Petrology , 39(8):1493-1526. DOI: 10.1093/petroj/39.8.1493
» https://doi.org/10.1093/petroj/39.8.1493 - Ulbrich H.H.G.J., Ulbrich M.N.C. 2000. The lujavrite and khibinite bodies in the Poços de Caldas alkaline massif, southeastern Brazil: a structural and petrographic study. Revista Brasileira de Geociências , 30(4):615-622.
- Ulbrich H.H.G.J., Demaiffe D., Vlach S.R.F., Ulbrich M.N.C. 2005. Structure and origin of the Poços de Caldas alkaline massif, SE Brazil Comin-Chiaramonti P., Gomes C.B. (eds.) Mesozoic to Cenozoic alkaline magmatism in the Brazilian Platform . São Paulo, Edusp/FAPESP, p. 367-418.
- Van Achterbergh E., Ryan C.G., Jackson S.E., Griffin W.L. 2001. Data reduction software for LA-ICP-MS: appendix : Silvester P.J. (ed.) Laser Ablation-ICP-Mass spectrometry in the Earth sciences: principles and applications . Mineralogical Association of Canada Short Course Series 29, Ottawa, Mineralogical Association of Canada, p. 239-243.
- Williams C.T. 1996. Analysis of rare earth minerals Jones A.P., Wall F., Williams C.T. (eds.) Rare earth minerals: chemistry, origin and ore deposits. Mineralogical Society Series 7, London, Chapman & Hall, p. 327-348.
- Wu F.-Y., Yang Y.-H., Marks M.A.W., Liu Z.-C., Zhou Q., Ge W.-C., Yang J.-S., Zhao Z.-S., Mitchell R.H., Markl G. 2010. In situ U-Pb, Nd and Hf isotopic analysis of eudialyte by LA-(MC)-ICP-MS. Chemical Geology , 273(1-2):8-34. DOI: http://dx.doi.org/10.1016/j.chemgeo.2010.02.007
» http://dx.doi.org/10.1016/j.chemgeo.2010.02.007
Publication Dates
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Publication in this collection
Jul-Sep 2016
History
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Received
13 June 2016 -
Accepted
09 Aug 2016