Figure 1:
(A) Geological sketch map of the Serra do Mar alkaline province in southeastern Brazil, modified from 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.). In the gray rectangle, the studied area. (B) Simplified geological map of part of the Mantiqueira Range. Alkaline dikes are represented by black squares (sampling point of fresh rocks) in the main drainage segments and by the strike direction of in situ bodies. PN, Ponte Nova alkaline massif (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. ); SALB, Serra da Água Limpa batolith; G-SN, gneisses of the Socorro nappe; QS-ET, quartzites and schists of Embu terrane (Precambrian basement units from Vinagre et al. 2014aVinagre R., Trouw R.A.J., Mendes J.C., Duffles P., Peternel R., Matos G. 2014a. New evidence of a magmatic arc in the southern Brasília Belt, Brazil: The Serra da Água Limpa batholith (Socorro-Guaxupé Nappe). Journal of South American Earth Science, 54:120-139.). R, main roadways; D, drainages. Reference Cities: SAP, Santo Antônio do Pinhal; CJ, Campos do Jordão; SM, Sapucaí Mirim.
Figure 2:
Mineral compositions of weakly to strongly silica-undersaturated alkaline dike series of the Mantiqueira Range. (A) Clinopyroxene compositions in the Wo-En-Fs system (cf. Morimoto et al. 1988Morimoto N., Fabries J., Ferguson A.K., Ginzburg I.V., Ross M., Seifert F.A., Zussman J., Aoki K., Gottardi G. 1988. Nomenclature of pyroxenes. Mineralogical Magazine, 52:535-550.). (B) Crystallization trends of clinopyroxenes compared with the main evolutionary trends for clinopyroxenes of alkaline complexes from southeastern Brazil. Fe* = (Fe2++Mn+Fe3+-Na). References: 1. São Sebastião Island (Bellieni et al. 1990Bellieni G., Montes-Lauar C.R., De Min A., Piccirillo E.M., Cavazzini G., Melfi A.J., Pacca I.G. 1990. Early and Late Cretaceous magmatism from São Sebastião island (SE-Brazil): geochemistry and petrology. Geochimica Brasiliensis, 4(1):59-83.); 2. Vitória Island (Motoki 1986Motoki A. 1986. Geologia e petrologia do maciço alcalino da Ilha de Vitória, SP. PhD Thesis, Instituto de Geociências, Universidade de São Paulo, São Paulo, 245 p.); 3. Monte de Trigo Island (Enrich 2005Enrich G.E.R. 2005. Petrogênese da suíte alcalina da Ilha Monte de Trigo, SP. PhD Thesis, Instituto de Geociências, Universidade de São Paulo, São Paulo, 229 p.); 4. Passa Quatro (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 Sciences, 6(4):237-252.) and Itatiaia (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.); 5. Morro Redondo (Brotzu et al. 1989Brotzu P., Beccaluva L., Conte A.M., Fonseca M., Garbarino C., Gomes C.B., Leong R., Macciotta G., Mansur R.L., Melluso L., Morbidelli L., Ruberti E., Sígolo J.B., Traversa G., Valença J.G. 1989. Petrological and geochemical studies of alkaline rocks from continental Brazil. 8. The syenitic intrusion of Morro Redondo, RJ. Geochimica Brasiliensis, 3(1):63-80.); 6. 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 Sciences, 24(1):93-115.); 7(a, b). Búzios Island (Gomes et al. 2017Gomes C.B., Alves F.R., Azzone R.G., Rojas G.E.E., Ruberti E. 2017. Geochemistry and petrology of the Buzios Island alkaline massif, SE, Brazil. Brazilian Journal of Geology, 47(1):127-145.). (C) Amphibole compositions in the Ti of the C-site vs. Mg#amp (MgT/(MgT+FeT, in apfu). (D) Biotite compositions on the AlIVvs. Fe/(Fe+Mg) (apfu) diagram. Symbols: strongly silica-undersaturated series, black diamonds; intermediate series, gray squares; weakly silica-undersaturated series, white triangles. Gray fields are representative of the respective mineral compositions in the Ponte Nova massif (Azzone 2008Azzone R.G. 2008. Petrogênese do maciço alcalino máfico-ultramáfico Ponte Nova (SP-MG). PhD Thesis, Universidade de São Paulo, São Paulo, 240 p.).
Figure 3:
Major-element discrimination diagrams for the weakly to strongly silica-undersaturated alkaline dike series of the Mantiqueira Range. (A) TAS (SiO2 vs. Na2O+K2O, in wt%) diagram (cf. Le Maitre 2002Le Maitre R.W. 2002. Igneous Rocks: A Classification and Glossary of Terms, second ed. Cambridge University Press, Cambridge.). Dashed line separates alkaline and subalkaline fields (after Irvine & Baragar 1971Irvine T.N. & Baragar W.R.A. 1971. A guide to chemical classification of the common volcanic rocks. Canadian Journal of Earth Sciences, 8(5):523-548.). (B) Normative mafics vs. normative nepheline diagram. (C) R1-R2 diagram (cf. De La Roche et al. 1980De La Roche H., Leterrier J., Grandclaude P., Marchal M. 1980. A classification of volcanic and plutonic rocks using R1R2-diagram and major-element analyses - Its relationships with current nomenclature. Chemical Geology, 29(1-4):183-210.). (D) Highly-potassic, potassic and sodic series diagram (after Middlemost 1975Middlemost E.A.K. 1975. The basalt clan. Earth-Science Reviews, 11(4):337-364.). Symbols: strongly-alkaline dike series (SAS), black diamonds; intermediate dike series (IS), gray squares; weakly-alkaline dike series (WAS), white triangles; phonolites, black circles. Average mineral poles compiled from Azzone (2008Azzone R.G. 2008. Petrogênese do maciço alcalino máfico-ultramáfico Ponte Nova (SP-MG). PhD Thesis, Universidade de São Paulo, São Paulo, 240 p.) are representative of the main assemblage found in the Ponte Nova massif. Abbreviations: ap, apatite; bt, biotite; cpx, clinopyroxene; fsp, feldspar; ilm, ilmenite; krs, kaersutite; mag, magnetite; nph, nepheline; ol, olivine; pl, plagioclase. The DT field is representative of primitive dikes described by 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.). The SALB field is representative of heterogeneous host rocks of the Serra da Água Limpa batolith (cf. Vinagre et al. 2014aVinagre R., Trouw R.A.J., Mendes J.C., Duffles P., Peternel R., Matos G. 2014a. New evidence of a magmatic arc in the southern Brasília Belt, Brazil: The Serra da Água Limpa batholith (Socorro-Guaxupé Nappe). Journal of South American Earth Science, 54:120-139.). PN1 and PN2 fields are representative of mafic cumulates and non-cumulatic intrusions from the nearby Ponte Nova massif, respectively (Azzone et al. 2016Azzone R.G., Munoz P.M., Enrich G.E.R, Alves A., Ruberti E., Gomes C.B. 2016. Petrographic, geochemical and isotopic evidence of crustal assimilation processes in the Ponte Nova alkaline mafic-ultramafic massif, SE Brazil. Lithos, 260:58-75.).
Figure 4:
Primitive mantle-normalized (McDonough & Sun 1995McDonough W.F. & Sun S. 1995. The composition of the Earth. Chemical Geology, 120(3-4):223-253.) incompatible element distribution for rocks of the (A) weakly silica-undersaturated series (WAS); (B) intermediate series (IS); (C) strongly silica-undersaturated series (SAS); (D) phonolites of the Mantiqueira Range. Negative anomalies of K, Zr, Hf, and Ti are compatible with carbonatites from around the world (Zeng et al. 2010Zeng G., Chen L., Xu X., Jiang S., Hofmann A.W. 2010. Carbonated mantle sources for Cenozoic intra-plate alkaline basalts in Shandong, North China. Chemical Geology, 273(1-2):35-45.), the feature suggesting melts with contribution from a carbonated-metasomatized peridotite source. However, negative anomalies of Pb are typical of alkaline magmas, and such a behavior is affected by extensive contribution of crustal components, as indicated in some occurrences of the weakly silica-undersaturated dike series. Crustal assimilation also seems to be the explanation for the near absence of the negative K anomaly and positive U anomalies.
Figure 5:
Chondrite-normalized (McDonough & Sun 1995McDonough W.F. & Sun S. 1995. The composition of the Earth. Chemical Geology, 120(3-4):223-253.) REE patterns for rocks of the weakly- to strongly-alkaline dike series of the Mantiqueira Range and nearby host rocks. Gray field is representative of the intermediate dike series.
Figure 6:
(A) Variation of 87Sr/86Sr vs. 143Nd/144Nd for weakly to strongly silica-undersaturated alkaline dike series of the Mantiqueira Range and nearby host rocks. Fields from Trindade Island and Alto Paranaíba Alkaline Province (APAP) compiled from Marques et al. (1999Marques L.S., Dupré B., Piccirillo E.M. 1999. Mantle source compositions of the Paraná Magmatic Province (southern Brazil): Evidence from trace element and Sr-Nd-Pb isotope geochemistry. Journal of Geodynamics, 28:439-458.), Gibson et al. (1995Gibson S.A., Thompson R.N., Leonardos O.H., Dickin A.P., Mitchell J.G. 1995. The Late Cretaceous impact of the Trindade mantle plume: Evidence from large-volume, mafic potassic magmatism in SE Brazil. Journal of Petrology, 36(1):189-229.) and Araújo et al. (2001Araújo A., Carlson R.W., Gaspar J.C., Bizzi L.A. 2001. Petrology of kamafugites and kimberlites from the Alto Paranaiba alkaline province, Minas Gerais, Brazil. Contributions to Mineralogy and Petrology, 142(2):163-177.). Field for dikes and massifs of the Serra do Mar alkaline province (SMP) compiled from 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 Sciences, 24(1):93-115.) and references therein. Mixing-model curves for the least radiogenic samples representative of the most primitive basic alkaline magmatism of the area (dike from 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., and a plug from Azzone et al. 2016Azzone R.G., Munoz P.M., Enrich G.E.R, Alves A., Ruberti E., Gomes C.B. 2016. Petrographic, geochemical and isotopic evidence of crustal assimilation processes in the Ponte Nova alkaline mafic-ultramafic massif, SE Brazil. Lithos, 260:58-75.; symbols, vertical crosses) to end-members of gneiss and metasyenogranite of the Serra da Água Limpa batholith (curves 1-3, data from Azzone et al. 2016Azzone R.G., Munoz P.M., Enrich G.E.R, Alves A., Ruberti E., Gomes C.B. 2016. Petrographic, geochemical and isotopic evidence of crustal assimilation processes in the Ponte Nova alkaline mafic-ultramafic massif, SE Brazil. Lithos, 260:58-75.) based on the Albarède (1995Albarède F. 1995. Introduction to Geochemical Modeling, Cambridge University Press. 543p.) formulae are plotted to evaluate crustal contribution processes (after Azzone et al. 2016Azzone R.G., Munoz P.M., Enrich G.E.R, Alves A., Ruberti E., Gomes C.B. 2016. Petrographic, geochemical and isotopic evidence of crustal assimilation processes in the Ponte Nova alkaline mafic-ultramafic massif, SE Brazil. Lithos, 260:58-75.). Mixing-model Curve 4 represent a pole of a sample in the Group 1 phonolites (MT-68c) to metasyenogranite end-member, indicating that phonolites could also be affected by crustal contribution. (B) Zoom of (A) diagram. DT field is representative of basic dikes of the Mantiqueira Range as described by 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.). PN1 and PN2 fields are representative of Ponte Nova intrusions showing lower and higher degrees of crustal contamination, respectively (Azzone et al. 2016Azzone R.G., Munoz P.M., Enrich G.E.R, Alves A., Ruberti E., Gomes C.B. 2016. Petrographic, geochemical and isotopic evidence of crustal assimilation processes in the Ponte Nova alkaline mafic-ultramafic massif, SE Brazil. Lithos, 260:58-75.).
Figure 7:
Argon-release age spectra for biotite samples of a tephriphonolite dike (ST-4H) with well-defined plateau ages (WMP). Bars are representative of 2σ errors.
Figure 8:
Primitive mantle-normalized (McDonough & Sun 1995McDonough W.F. & Sun S. 1995. The composition of the Earth. Chemical Geology, 120(3-4):223-253.) trace element ratios for the weakly to strongly silica-undersaturated alkaline dike series of the Mantiqueira Range and nearby host rocks. (A) (Rb/Sr)N vs. (Ce/Pb)N diagram. The inset presents the entire range of (Rb/Sr)N obtained for host rocks. (B) (Ce/Pb)N vs. 143Nd/144Ndi diagram. The inset presents the entire range of (Ce/Pb)N obtained for host rocks. Possible trends of crustal contribution processes are indicated by the dashed lines. (C) (Ba/Sr)N vs. (Rb/Sr)N diagram. Fields for low-contaminated (PN1) and highly-contaminated intrusions of the Ponte Nova massif (PN2) are shown for comparison. Host rock data and biotite compositional controls from Azzone et al. (2016Azzone R.G., Munoz P.M., Enrich G.E.R, Alves A., Ruberti E., Gomes C.B. 2016. Petrographic, geochemical and isotopic evidence of crustal assimilation processes in the Ponte Nova alkaline mafic-ultramafic massif, SE Brazil. Lithos, 260:58-75.). High levels of Ce/Pb for low levels of Rb/Sr and Ba/Sr are compatible with alkaline mantle-derived melts (Orejana et al. 2008Orejana D., Villaseca C., Billström K., Paterson B.A. 2008. Petrogenesis of Permian alkaline lamprophyres and diabases from the Spanish Central System and their geodynamic context within Western Europe. Contributions to Mineralogy and Petrology, 156(4):477-500.), whereas high levels of Rb/Sr and Ba/Sr for low levels of Ce/Pb are typical of the contribution from partial melts of crustal basement rocks. (C) Same as (B), but plotting only low-degree contaminated dikes from each alkaline series, compared with fertile source ideal composition (primitive mantle values, PM) and with the field for kamafugite/kimberlite compositions of the Alto Paranaíba province. All values of Rb/Sr and Ba/Sr are higher than PM, suggesting a metasomatized mantle source, and within the field for kamafugite/kimberlite compositions.
Figure 9:
(Hf/Y)N vs. (La/Zr)N (primitive mantle-normalized; McDonough & Sun 1995McDonough W.F. & Sun S. 1995. The composition of the Earth. Chemical Geology, 120(3-4):223-253.) for the most primitive samples of the weakly- to strongly silica-undersaturated alkaline dike series of the Mantiqueira Range. Non-modal batch melting models for different mantle sources are also shown (complemented from Azzone et al. 2013Azzone R.G., Enrich G.E.R., Gomes C.B., Ruberti E. 2013. Trace element composition of parental magmas from mafic-ultramafic cumulates determined by in situ mineral analyses: The Juquiá mafic-ultramafic alkaline-carbonatite massif, SE Brazil. Journal of South American Earth Sciences 41:5-21.). Partition coefficients from Green et al. (2000Green T.H., Blundy J.D., Adam J., Yaxley G.M. 2000. SIMS determination of trace element partition coefficients between garnet, clinopyroxene and hydrous basaltic liquids at 2-7.5 GPa and 1080-1200oC. Lithos, 53:165-187.), Adam & Green (2003Adam J. & Green T. 2003. The influence of pressure, mineral composition and water on trace element partitioning between clinopyroxene, amphibole and basanitic melts. European Journal of Mineralogy, 15(5):831-841.), and Zanetti et al. (2004Zanetti A., Tiepolo M., Oberti R., Vannucci R. 2004. Trace-element partitioning in olivine: Modeling of a complete data set from a synthetic hydrous basanite melt. Lithos, 75(1-2):39-54.). Trace element compositions of the metasomatic veins (blue square) based on primitive mantle (McDonough & Sun 1995McDonough W.F. & Sun S. 1995. The composition of the Earth. Chemical Geology, 120(3-4):223-253.) plus 1.5 wt% of a mantle Mg-carbonatite (Hoernle et al. 2002Hoernle K., Tilton G., LeBas M.J, Duggen S., Garbe-Schönberg D. 2002. Geochemistry of oceanic carbonatites compared with continental carbonatites: Mantle recycling of oceanic crustal carbonate. Contributions to Mineralogy and Petrology, 142(5):520-542.). Trace element compositions of wall-rock (black square) based on primitive mantle composition (McDonough & Sun 1995McDonough W.F. & Sun S. 1995. The composition of the Earth. Chemical Geology, 120(3-4):223-253.). Modal compositions of mantle source residua: inverted triangles, off-craton garnet lherzolite; black diamonds, primitive mantle garnet lherzolite; blue diamonds, theoretical wehrlite. Italic numbers indicate the degree of partial melting. Gray field represents Serra do Mar province primitive dikes (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 Sciences, 24(1):93-115. and references therein). Dashed fields: composition of calculated primitive melts and dikes from Ponta Grossa arch occurrences (Azzone et al. 2013Azzone R.G., Enrich G.E.R., Gomes C.B., Ruberti E. 2013. Trace element composition of parental magmas from mafic-ultramafic cumulates determined by in situ mineral analyses: The Juquiá mafic-ultramafic alkaline-carbonatite massif, SE Brazil. Journal of South American Earth Sciences 41:5-21., Menezes et al. 2015Menezes S.G., Azzone R.G., Rojas G.E.E., Ruberti E., Cagliarani R., Gomes C.B., Chmyz L. 2015. The antecryst compositional influence on Cretaceous alkaline lamprophyre dykes, SE Brazil. Brazilian Journal of Geology, 45(1):79-93., Chmyz et al. 2017Chmyz L., Arnaud N., Biondi J.C., Azzone R.G., Bosch D., Ruberti E. (2017). Ar-Ar ages, Sr-Nd isotope geochemistry, and implications for the origin of the silicate rocks of the Jacupiranga ultramafic-alkaline complex (Brazil). Journal of South American Earth Sciences, 77:286-309.).