2.13 Ga Lawsonite/Barroisite-Bearing E-Morb Signature Metagabbro Associated with Spinel Metaperidotite from Itaguara (São Francisco Craton, Brazil): Oldest Blueschist-Facies Fragment of Oceanic Moho?

Alexandre de Oliveira Chaves

Institute of Geosciences (IGC), Federal University of Minas Gerais (UFMG), Av. Antônio Carlos, 6627-Pampulha, Belo Horizonte, MG, CEP 31270-901, Brazil

DOI: https://doi.org/10.36956/eps.v3i2.1068

Received: 30 March 2024; Received in revised form: 16 May 2024; Accepted: 23 May 2024; Published: 14 June 2024

Copyright © 2024 Author(s). Published by Nan Yang Academy of Sciences Pte. Ltd.

Creative Commons LicenseThis is an open access article under the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) License.


In close association with Paleoproterozoic retroeclogite and accretionary prism-related mica-quartz schist, a 2.13 Ga (metamorphic titanite U-Pb age) lawsonite/barroisite-bearing E-MORB signature metagabbro associated with spinel metaperidotite is found in the Itaguara Sequence from southern São Francisco craton, Brazil. Petrography and pressure-temperature equilibrium phase diagrams suggest that the metagabbro experienced blueschist-facies metamorphism, attaining peak metamorphic conditions at ~16 kbar and ~450 °C during subduction. The retrograde metamorphic path crossed epidote amphibolite-facies, in which the mineral assemblage found in metaperidotite (olivine, clinopyroxene, spinel, serpentine, chlorite, talc, and tremolite) was stable during a ca. 2.1 Ga continental collision-related exhumation that occurred between the Archean Campo Belo/Bonfim and Divinópolis complexes. This geological framework suggests that the metagabbro and adjacent spinel metaperidotite represent a subducted and exhumed blueschist-facies fragment of a Paleoproterozoic oceanic Mohorovičić (Moho) discontinuity, thus establishing the Itaguara metagabbro as the oldest-known occurrence of retrogressed blueschist and providing evidence for the activity of the modern-style plate tectonics more than 2 Gyr ago.

Keywords: Metagabbro and metaperidotite; Blueschist; Paleoproterozoic; Moho; São Francisco craton


[1] Maruyama, S., Liou, J.G., Terabayashi, M., 1996. Blueschists and eclogites of the world and their exhumation. International Geology Review. 38, 485–594. DOI: https://doi.org/10.1080/00206819709465347

[2] Agard, P., Yamato, P., Jolivet, L., et al., 2009. Exhumation of oceanic blueschists and eclogites in subduction zones: Timing and mechanisms. Earth-Science Reviews. 92, 53–79. DOI: https://doi.org/10.1016/j.earscirev.2008.11.002

[3] Sanità, E., Di Rosa, M., Lardeaux, J.-M., et al., 2022. The Moglio-Testico Unit (Ligurian Alps, Italy) as subducted metamorphic oceanic fragment: stratigraphic, structural and metamorphic constraints. Minerals. 12(11), 1343. DOI: https://doi.org/10.3390/min12111343

[4] Palin, R.M., Santosh, M., 2021. Plate tectonics: what, where, why, and when? Gondwana Research. 100, 3–24. DOI: https://doi.org/10.1016/j.gr.2020.11.001

[5] Chaves, A.O., Goulart, L.E.A., Coelho, R.M., et al., 2019. High-pressure eclogite facies metamorphism and decompression melting recorded in paleoproterozoic accretionary wedge adjacent to probable ophiolite from Itaguara (southern São Francisco Craton—Brazil). Journal of South American Earth Sciences. 94, 102226. DOI: https://doi.org/10.1016/j.jsames.2019.102226

[6] Chaves, A.O., Coelho, R.M., 2020. Reply to "Comments to high-pressure eclogite facies metamorphism and decompression melting recorded in Paleoproterozoic accretionary wedge adjacent to probable ophiolite from Itaguara (southern São Francisco Craton—Brazil)". Journal of South American Earth Sciences. 99, 102510. DOI: https://doi.org/10.1016/j.jsames.2020.102510

[7] Aguilar, C., Alkmim, F.F., Lana, C. et al., 2017. Palaeoproterozoic assembly of the São Francisco craton, SE Brazil: new insights from U-Pb titanite and monazite dating. Precambrian Research. 289, 95–115. DOI: https://doi.org/10.1016/j.precamres.2016.12.001

[8] Miranda, D.A., Chaves, A.O., Dussin, I.A., et al., 2020. Paleoproterozoic khondalites in Brazil: a case study of metamorphism and anatexis in khondalites from Itapecerica supracrustal succession of the southern São Francisco Craton. International Geology Review. 64(4), 397–421. DOI: https://doi.org/10.1080/00206814.2020.1716273

[9] Chaves, A.O., Porcher, C.C., 2020. Petrology, geochemistry and Sm-Nd systematics of the Paleoproterozoic Itaguara retroeclogite from São Francisco/Congo Craton: one of the oldest records of the modern-style plate tectonics. Gondwana Research. 87, 224–237. DOI: https://doi.org/10.1016/j.gr.2020.06.014

[10] Setiawan, N.I., Osanai, Y., Nakano, N., et al., 2015. Metamorphic evolution of garnet bearing epidote-barroisite schist from the Meratus Complex in South Kalimantan, Indonesia. Indonesian Journal on Geoscience. 2(3), 139–156. DOI: https://doi.org/10.17014/ijog.2.3.139-156

[11] Kato, R., Hirajima, T., 2017. Petrology and possible significance of barroisite–bearing metabasite from the Kebara Formation in NW Kii Peninsula. Journal of Mineralogical and Petrological Sciences. 112, 40–45. DOI: https://doi.org/10.2465/jmps.160719a

[12] Goulart, L.E.A., Carneiro, M.A., 2010. Paleoproterozoic mafic-ultramafic magmatism in Southern São Francisco craton: the Itaguara layered sequence. 45o Congresso Brasileiro de Geologia, Sociedade Brasileira de Geologia, Belém, Anais (in Portuguese).

[13] Whitney, D.L., Fornash, K.F., Kang, P., et al., 2020. Lawsonite composition and zoning as tracers of subduction processes: A global review. Lithos. 370–371, 105636. DOI: https://doi.org/10.1016/j.lithos.2020.105636

[14] Tsujimori, T., Ernst, W.G., 2014. Lawsonite blueschists and lawsonite eclogites as proxies for palaeo-subduction zone processes: A review. Journal of Metamorphic Geology. 32(5), 437–454. DOI: https://doi.org/10.1111/jmg.12057

[15] Almeida, F.F.M., Hasui, Y., Brito Neves, B.B. et al., 1981. Brazilian structural provinces: An introduction. Earth Science Reviews. 17(1–2), 1–29. DOI: https://doi.org/10.1016/0012-8252(81)90003-9

[16] Pedrosa Soares, A.C., Noce, C.M., Wiedemann, C.M., et al., 2001. The Araçuaí-West-Congo orogen in Brazil: an overview of a confined orogen formed during Gondwanaland assembly. Precambrian Research. 110(1–4), 307–323. DOI: https://doi.org/10.1016/S0301-9268(01)00174-7

[17] Pimentel, M., Dardenne, M., Fuck, R., et al., 2001. Nd isotopes and the provenance of detrital sediments of the Neoproterozoic Brasılia Belt, central Brazil. Journal of South American Earth Sciences. 14(6), 571–585. DOI: https://doi.org/10.1016/S0895-9811(01)00041-4

[18] Teixeira, W., Carneiro, M.A., Noce, C.M., et al., 1996. Pb, Sr and Nd isotope constraints on the Archean evolution of the gneissic-granitoid in the southern São Francisco Craton, Brazil. Precambrian Research. 78(1–3), 151–164. DOI: https://doi.org/10.1016/0301-9268(95)00075-5

[19] Dorr, J.V.N., 1969. Physiographic, stratigraphic and structural development of Quadrilatero Ferrifero, Minas Gerais, Brazil. USGS/DNPM Professional paper. 641-A, 110. DOI: https://doi.org/10.3133/pp641A

[20] Baltazar, O.F., Zucchetti, M., 2007. Lithofacies associations and structural evolution of the Archean Rio das Velhas greenstone belt, Quadrilátero Ferrífero, Brazil: a review of the setting of gold deposits. Ore Geology Reviews. 32, 471–499. DOI: https://doi.org/10.1016/j.oregeorev.2005.03.021

[21] Machado, N., Schrank, A., Noce, C.M., et al., 1996. Ages of detrital zircon from Archean-Paleoproterozoic sequences: implications for Greenstone Belt setting and evolution of a Transamazonian foreland basin in Quadrilátero Ferrífero, southeast Brazil. Earth and Planetary Science Letters. 141, 259–276. DOI: https://doi.org/10.1016/0012-821X(96)00054-4

[22] Machado Filho, L., Ribeiro, M.W., Gonzalez, S.R., et al., 1983. SF 23/24 Sheets, Rio de Janeiro/Vitoria: geology, geomorphology, pedology, vegetation, potential use of the land/RADAMBRASIL Project [v. 32]. O Projeto: Rio de Janeiro/Vitória, 32. pp 36–45. Available from: https://biblioteca.ibge.gov.br/biblioteca-catalogo?id=217129&view=detalhes (in Portuguese).

[23] Lana, C., Alkmim, F.F., Armstrong, R., et al., 2013. The ancestry and magmatic evolution of Archaean TTG rocks of the Quadrilátero Ferrífero province, southeast Brazil. Precambrian Research. 231, 157–173. DOI: https://doi.org/10.1016/j.precamres.2013.03.008

[24] Romano, R., Lana, C., Alkimim, F.F., et al., 2013. Stabilization of the southern portion of the Sao Francisco Craton, SE Brazil, through a long-lived period of potassic magmatism. Precambrian Research. 224, 143–159.

[25] Farina, F., Albert, C., Dopico, C.M., et al., 2016. The Archean-Paleoproterozoic evolution of the Quadrilátero Ferrífero (Brasil): Current models and open questions. Journal of South American Earth Sciences. 68, 4–21. DOI: https://doi.org/10.1016/j.jsames.2015.10.015

[26] Moreira, H., Lana, C., Nalini, H.A., 2016. The detrital zircon record of an Archaean convergent basin in the Southern São Francisco Craton, Brazil. Precambrian Research. 275, 84–99. DOI: https://doi.org/10.1016/j.precamres.2015.12.015

[27] CPRM – Brazilian Geological Survey and CODEMIG, Companhia de Desenvolvimento Econômico de Minas Gerais, 2014. Mapa Geológico do Estado de Minas Gerais. Escala 1:1000000 DVD-rom. Available from: https://rigeo.cprm.gov.br/jspui/handle/doc/20786/ (in Portuguese).

[28] Teixeira, W., Ávila, C.A., Dussin, I.A., et al., 2015. A juvenile accretion episode (2.35–2.32 Ga) in the Mineiro belt and its role to the Minas accretionary orogeny: zircon U-Pb-Hf and geochemical evidences. Precambrian Research. 256, 148–169. DOI: https://doi.org/10.1016/j.precamres.2014.11.009

[29] Noce, C.M., Machado, N., Teixeira, W., 1998. U-Pb geochronology of gneisses and granitoids in the Quadrilátero Ferrífero (southern São Francisco Craton): age constraints for Archean and Paleoproterozoic magmatism and metamorphism. Brazilian Journal of Geology. 28, 95–102. DOI: https://doi.org/10.25249/0375-7536.199895102

[30] Ávila, C.A., Teixeira, W., Bongiolo, E.M., et al., 2014. Rhyacian evolution of subvolcanic and metasedimentary rocks of the southern segment of the Mineiro belt, Sao Francisco Craton, Brazil. Precambrian Research. 243, 221–251. DOI: https://doi.org/10.1016/j.precamres.2013.12.028

[31] Noce, C.M., Pedrosa Soares, A.C., Silva, L.C., et al., 2007. Evolution of polycyclic basement complexes in the Araçuaí Orogen, based on U-Pb SHRIMP data: Implications for Brazil-Africa links in Paleoproterozoic time. Precambrian Research. 159, 60–78. DOI: https://doi.org/10.1016/j.precamres.2007.06.001

[32] Alkmim, F.F., Marshak, S., 1998. Transamazonian Orogeny in the Southern São Francisco Craton Region, Minas Gerais, Brazil: Evidence for Paleoproterozoic collision and collapse in the Quadrilátero Ferrífero. Precambrian Research. 90, 29–58. DOI: https://doi.org/10.1016/S0301-9268(98)00032-1

[33] Campos, J.C.S., Carneiro, M.A., 2008. Neoarchean and Paleoproterozoic granitoids marginal to the Jeceaba-Bom Sucesso lineament (SE border of the southern São Francisco Craton): genesis and tectonic evolution. Journal of South American Earth Sciences. 26, 463–484. DOI: https://doi.org/10.1016/j.jsames.2008.09.002

[34] Carvalho, B.B., Janasi, V.A., Sawyer, E.W., 2017. Evidence for Paleoproterozoic anatexis and crustal reworking of Archean crust in the São Francisco Craton, Brazil: A dating and isotopic study of the Kinawa migmatite. Precambrian Research. 291, 98–118. DOI: https://doi.org/10.1016/j.precamres.2017.01.019

[35] Chaves, A.O., Campello, M.S., Pedrosa Soares, A.C., 2015. Monazite U-Th-PbT age of the sillimanite-cordierite-garnet-biotite gneiss from Itapecerica (MG) and the actuation of the Rhyacian/Orosirian orogeny in the inner part of the southern São Francisco Craton. Geociências. 34, 324–334. Available from: https://www.revistageociencias.com.br/geociencias-arquivos/34/volume34_3_files/34-3-artigo-01.pdf (in Portuguese).

[36] Chaves, A.O., Pires, A.C.C., Brasil, M.F.A., 2021. New knowledge update on mafic dyke swarms of Minas Gerais (Brazil): Fragments of ancient large igneous provinces highlighted by aeromagnetometry. Brazilian Journal of Geophysics. 39(2), 227–235. DOI: http://dx.doi.org/10.22564/rbgf.v39i3.2096

[37] Goulart, L.E.A., Carneiro, M.A., 2008. General characteristics and lithogeochemistry of the Itaguara layered (ultramafic-mafic) sequence, southern São Francisco Craton. Geochimica Brasiliensis. 22, 045–072.

[38] Pinheiro, S.O., Nilson, A.A., 2000. Metakomatiitic and meta-ultramafic rocks from the Rio Manso region, Minas Gerais: geology, textures and metamorphism. Revista Brasileira de Geociências. 30, 417–419.

[39] de Capitani, C., Petrakakis, K., 2010. The computation of equilibrium assemblage diagrams with Theriak/Domino software. American Mineralogist. 95, 1006-1016. DOI: https://doi.org/10.2138/am.2010.3354

[40] Holland, T.J.B., Powell, R., 2011. An improved and extended internally consistent thermodynamic dataset for phases of petrological interest, involving a new equation of state for solids. Journal of Metamorphic Geology. 29(3), 333–383. DOI: https://doi.org/10.1111/j.1525-1314.2010.00923.x

[41] Van Achterbergh, E., Ryan, C.G., Jackson, S.E., et al., 2001. Data reduction software for LA-ICP-MS: Appendix. In: Sylvester P.J. (ed.). Mineralogical Association of Canada Short Course Series. 29, 239–243.

[42] Griffin, W.L., Powell, W.J., Pearson, N.J., et al., 2008. Glitter: Data reduction software for laser ablation ICP-MS. In: Sylvester P.J. (ed.), Laser ablation ICP-MS in the Earth sciences: Current practices and outstanding issues. Mineralogical Association of Canada Short Course Series. 40, 308–311.

[43] Gerdes, A., Zeh, A., 2006. Combined U–Pb and Hf isotope LA-(MC-)ICP-MS analyses of detrital zircons: Comparison with SHRIMP and new constraints for the provenance and age of an Armorican metasediment in central Germany. Earth and Planetary Science Letters. 249, 47–61. DOI: https://doi.org/10.1016/j.epsl.2006.06.039

[44] Gerdes, A., Zeh, A,, 2009. Zircon formation versus zircon alteration—New insights from combined U-Pb and Lu-Hf in-situ LA-ICP-MS analyses of Archaean zircons from the Limpopo Belt. Chemical Geology. 261, 230–243. DOI: https://doi.org/10.1016/j.chemgeo.2008.03.005

[45] Chew, D.M., Petrus, J.A., Kamber, B.S., 2014. U-Pb LA-ICP-MS dating using accessory mineral standards with variable Pbc. Chemical Geology. 363, 185–199. DOI: http://dx.doi.org/10.1016/j.chemgeo.2013.11.006

[46] Ludwig, K.R., 2003. Isoplot 3.00: A geochronological toolkit for Microsoft Excel. Berkeley Geochronology Center, Berkeley, 70.

[47] Mazoz, A., Gonçalves, G.O., Lana, C., et al., 2022. Khan river and bear lake: two natural titanite reference materials for high-spatial resolution U-Pb microanalysis. Geostandards and Geoanalytical Research. 46(4), 701–733. DOI: https://doi.org/10.1111/ggr.12444

[48] Whitney, D.L., Evans, B.W., 2010. Abbreviations for names of rock-forming minerals. American Mineralogist. 95, 185–187. DOI: https://doi.org/10.2138/am.2010.3371

[49] Leake, B.E., Woolley, A.R., Arps, C.E.S., et al., 1997. Nomenclature of amphiboles: report of the subcommittee on amphiboles of the international mineralogical commission on new minerals and mineral names. Mineralogical Magazine. 61, 295–310. DOI: https://doi.org/10.1180/minmag.1997.061.405.13

[50] Winter, J.D., 2014. Principles of igneous and metamorphic petrology, 2 ed. Pearson Education Limited: Harlow. pp. 738. Available from: https://www.whitman.edu/geology/winter/Winter_Principles%20of%20Igneous%20and%20Metamorphic%20Petrology%20by%20JOHN%20D.%20WINTER-1.pdf

[51] Ravna, E.K., 2000. Distribution of Fe2+ and Mg between coexisting garnet and hornblende in synthetic and natural systems: an empirical calibration of the garnet-hornblende Fe–Mg geothermometer. Lithos. 53, 265–277. DOI: https://doi.org/10.1016/S0024-4937(00)00029-3

[52] Palin, R.M., Santosh, M., Cao, W., et al., 2020. Secular change and the onset of plate tectonics on Earth. Earth Science Reviews. 207, 103172. DOI: https://doi.org/10.1016/j.earscirev.2020.103172

[53] Kamzolkin, V.A., Ivanov, S.D., Konilov, A.N., 2016. Empirical phengite geobarometer: Background, calibration, and application. Geology of Ore Deposits. 58(8), 613–622. DOI: https://doi.org/10.1134/S1075701516080092

[54] Xia, L., Li, X., 2019. Basalt geochemistry as a diagnostic indicator of tectonic setting. Gondwana Research. 65, 43–67. DOI: https://doi.org/10.1016/j.gr.2018.08.006

[55] Irvine, T.N., Baragar, W.R.A., 1971. A guide to the chemical classification of common volcanic rocks. Canadian Journal of Earth Sciences. 8, 523–548. DOI: https://doi.org/10.1139/e71-055

[56] Pearce, J.A., Cann, J.R., 1973. Tectonic setting of basic volcanic rocks determined using trace element analyses. Earth and Planetary Science Letters. 19, 290–300. DOI: https://doi.org/10.1016/0012-821X(73)90129-5

[57] Sun, S.S., McDonough, W.F., 1989. Chemical and isotopic systematics of oceanic basalts: Implications for mantle composition and processes. Magmatism in the Ocean Basins. 42, 313–345. DOI: https://doi.org/10.1144/GSL.SP.1989.042.01.19

[58] Liang, J.L., Ding, X., Sun, X.M., et al., 2009. Nb/Ta fractionation observed in eclogites from the Chinese Continental Scientific Drilling Project. Chemical Geology. 268, 27–40. DOI: https://doi.org/10.1016/j.chemgeo.2009.07.006

[59] Hernández-Uribe, D., Palin, R.M., 2019. A revised petrological model for subducted oceanic crust: Insights from phase equilibrium modeling. Journal of Metamorphic Geology. 37(6), 745–768. DOI: https://doi.org/10.1111/jmg.12483

[60] Pearce, J.A., 2008. Geochemical fingerprinting of oceanic basalts with applications to ophiolite classification and the search for Archean oceanic crust. Lithos. 100, 14–48. DOI: https://doi.org/10.1016/j.lithos.2007.06.016

[61] Clarke, G.L., Powell, R., Fitzherbert, J.A., 2006. The lawsonite paradox: a comparison of field evidence and mineral equilibria modelling. Journal of Metamorphic Geology. 24, 715–725. DOI: https://doi.org/10.1111/j.1525-1314.2006.00664.x

[62] Zack, T., Rivers, T., Brumm, R., et al., 2004. Cold subduction of oceanic crust: Implications from a lawsonite eclogite from the Dominican Republic. European Journal of Mineralogy. 16, 909–916.

[63] Chen, Y., Ye, K., Wu, T.F., et al., 2013. Exhumation of oceanic eclogites: thermodynamic constraints on pressure, temperature, bulk composition and density. Journal of Metamorphic Geology. 31, 549–570. DOI: https://doi.org/10.1111/jmg.12033

[64] Chaves, A.O., Dutra, A.C.O.M., 2020. Collisional event and thermal events of Proterozoic age recorded by monazite included in corundum from Itaguara (southern São Francisco Craton, Brazil). Comunicações Geológicas. 107(1), 5–12. Available from: https://repositorio.lneg.pt/bitstream/10400.9/3568/1/evento-colisional-e-eventos-t%C3%A9rmicos-proteroz%C3%B3icos-registados-2020.pdf (in Portuguese).

[65] Stern, R.J., Tsujimori, T., Harlow, G.E., et al., 2013. Plate tectonic gemstones. Geology. 41, 723–726. DOI: https://doi.org/10.1130/G34204.1

[66] Brown, M., Johnson, T., 2019. Metamorphism and the evolution of subduction on Earth. American Mineralogist. 104, 1065–1082. DOI: https://doi.org/10.2138/am-2019-6956

[67] Möller, A., Appel, P., Mezger, K., et al., 1995. Evidence for a 2 Ga subduction zone: Eclogites in the Usagaran belt of Tanzania. Geology. 23(12), 1067–1070. DOI: https://doi.org/10.1130/0091-7613(1995)023<1067:EFAGSZ>2.3.CO;2

[68] Zhao, G., Cawood, P.A., Wilde, S.A., et al., 2001. High-pressure granulites (retrograded eclogites) from the Hengshan Complex, North China Craton: petrology and tectonic implications. Journal of Petrology. 42(6), 1141–1170. DOI: https://doi.org/10.1093/petrology/42.6.1141

[69] Glassley, W.E., Korstgard, J.A., Storensen, K., et al., 2014. A new UHP metamorphic complex in the ~1.8 Ga Nagssugtoqidian orogen of west Greenland. American Mineralogist. 99, 1315–1334. DOI: https://doi.org/10.2138/am.2014.4726

[70] Weller, O., St-Onge, M., 2017. Record of modern-style plate tectonics in the Palaeoproterozoic Trans-Hudson orogen. Nature Geoscience. 10, 305–311. DOI: https://doi.org/10.1038/ngeo2904

[71] François, C., Debaille, V., Paquette, J.L., et al., 2018. The earliest evidence for modern-style plate tectonics recorded by HP–LT metamorphism in the Paleoproterozoic of the Democratic Republic of the Congo. Scientific Reports. 8, 15452. DOI: https://doi.org/10.1038/s41598-018-33823-y

[72] Loose, D., Schenk, V., 2018. 2.09 Ga old eclogites in the Eburnian-Transamazonian orogen of southern Cameroon: significance for Palaeoproterozoic plate tectonics. Precambrian Research. 304, 1–11. DOI: https://doi.org/10.1016/j.precamres.2017.10.018

[73] Bouyo, M.H., Penaye, J., Mouri, H., et al., 2019. Eclogite facies metabasites from the Paleoproterozoic Nyong Group, SW Cameroon: Mineralogical evidence and implications for a high-pressure metamorphism related to a subduction zone at the NW margin of the Archean Congo Craton. Journal of African Earth Sciences. 149, 215–234. DOI: https://doi.org/10.1016/j.jafrearsci.2018.08.010

[74] Chaves, A.O., 2021. Columbia (Nuna) supercontinent with external subduction girdle and concentric accretionary, collisional and intracontinental orogens permeated by large igneous provinces and rifts. Precambrian Research. 352, 106017. DOI: https://doi.org/10.1016/j.precamres.2020.106017