Abstract
Vanadium occurs in multiple valence states in nature, whereas Nb is exclusively pentavalent. Both are compatible in rutile, but the relationship of V–Nb partitioning and dependence on oxygen fugacity (expressed as fO2) has not yet been systematically investigated. We acquired trace-element concentrations on rutile grains (n = 86) in nine eclogitic samples from the Dabie-Sulu orogenic belt by laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) and combined them with published results in order to assess the direct and indirect effects of oxygen fugacity on the partitioning of V and Nb into rutile. A well-defined negative correlation between Nb (7–1,200 ppm) and V concentrations (50–3,200 ppm) was found, documenting a competitive relationship in the rutile crystal that does not appear to be controlled by bulk rock or mineral compositions. Based on the published relationship of RtDV and V valence with ∆QFM, we suggest that the priority order of V incorporation into rutile is V4+ > V3+ > V5+. The inferred Nb–V competitive relationship in rutile from the Dabie-Sulu orogenic belt could be explained by decreasing fO2 due to dehydration reactions involving loss of oxidizing fluids during continental subduction: The increased proportion of V3+ (expressed as V3+/∑V) and attendant decrease in RtDV is suggested to lead to an increase in rutile lattice sites available for Nb5+. A similar effect may be observed under more oxidizing conditions. When V5+/∑V increases, RtDV shows a dramatic decline and Nb concentration increases considerably. This is possibly documented by rutile in highly metasomatized and oxidized MARID-type (MARID: mica–amphibole–rutile–ilmenite–diopside) mantle xenoliths from the Kaapvaal craton, which also show a negative V–Nb covariation. In addition, their Nb/Ta covaries with V concentrations: For V concentrations <1,250 ppm, Nb/Ta ranges between 35 and 45, whereas for V > 1,250 ppm, Nb/Ta is considerably lower (5–15). This relationship is mainly controlled by a change in Nb concentrations, suggesting that the indirect dependence of RtDNb on fO2, which is not mirrored in RtDTa, can exert considerable influence on rutile Nb–Ta fractionation.
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References
Aulbach S, O’Reilly SY, Griffin WL, Pearson NJ (2008) Subcontinental lithospheric mantle origin of high niobium/tantalum ratios in eclogites. Nat Geosci 1(7):468–472
Aulbach S, O’Reilly SY, Pearson NJ (2011) Constraints from eclogite and MARID xenoliths on origins of mantle Zr/Hf-Nb/Ta variability. Contrib Mineral Petrol 162(5):1047–1062
Barth MG, McDonough WF, Rudnick RL (2000) Tracking the budget of Nb and Ta in the continental crust. Chem Geol 165(3–4):197–213
Barth MG, Rudnick RL, Horn I, McDonough WF, Spicuzza MJ, Valley JW, Haggerty SE (2001) Geochemistry of xenolithic eclogites from West Africa, Part I: a link between low MgO eclogites and Archean crust formation. Geochim Cosmochim Acta 65(9):1499–1527
Barth MG, Foley SF, Horn I (2002a) Partial melting in Archean subduction zones: constraints from experimentally determined trace element partition coefficients between eclogitic minerals and tonalitic melts under upper mantle conditions. Precambrian Res 113(3–4):323–340
Barth MG, Rudnick RL, Horn I, McDonough WF, Spicuzza MJ, Valley JW, Haggerty SE (2002b) Geochemistry of xenolithic eclogites from West Africa, part 2: origins of the high MgO eclogites. Geochim Cosmochim Acta 66(24):4325–4345
Blundy J, Wood B (2003) Partitioning of trace elements between crystals and melts. Earth Planet Sci Lett 210(3–4):383–397
Brandon AD, Draper DS (1996) Constraints on the origin of the oxidation state of mantle overlying subduction zones: an example from Simcoe, Washington, USA. Geochim Cosmochim Acta 60:1739–1749
Bromiley GD, Redfern SAT (2008) The role of TiO2 phases during melting of subduction-modified crust: implications for deep mantle melting. Earth Planet Sci Lett 267(1–2):301–308
Canil D (1997) Vanadium partitioning and the oxidation state of Archaean komatiite magmas. Nature 389(6653):842–845
Canil D (1999) Vanadium partitioning between orthopyroxene, spinel and silicate melt and the redox states of mantle source regions for primary magmas. Geochim Cosmochim Acta 63(3–4):557–572
Canil D (2002) Vanadium in peridotites, mantle redox and tectonic environments: Archean to present. Earth Planet Sci Lett 195(1–2):75–90
Canil D, Fedortchouk Y (2000) Clinopyroxene-liquid partitioning for vanadium and the oxygen fugacity during formation of cratonic and oceanic mantle lithosphere. J Geophys Res Solid Earth 105(B11):26003–26016
Chen, ZY (2008) Study on accessory minerals in UHP rocks from drilling core of CCSD and outcrops of North Jiangsu, China: published. PhD Thesis, Chinese Academy of Geological Sciences
Chen RX, Zheng YF, Zhao ZF, Tang J, Wu FY, Liu XM (2007) Zircon U-Pb age and Hf isotope evidence for contrasting origin of bimodal protoliths for ultrahigh-pressure metamorphic rocks from the Chinese Continental Scientific Drilling project. J Metamorph Geol 25(8):873–894
Cong B, Zhai MG, Carswell DA, Wilson RN, Wang QC, Zhao ZY, Windley BF (1995) Petrogenesis of ultrahigh-pressure rocks and their country rocks at Shuanghe in Dabieshan, central China. Eur J Mineral 7(1):119–138
Cottrell E, Kelley KA (2011) The oxidation state of Fe in MORB glasses and the oxygen fugacity of the upper mantle. Earth Planet Sci Lett 305(3–4):270–282
Creighton S, Stachel T, Matveev S, Hofer H, McCammon C, Luth RW (2009) Oxidation of the Kaapvaal lithospheric mantle driven by metasomatism. Contrib Mineral Petrol 157(4):491–504
Defant MJ, Drummond MS (1990) Derivation of some modern arc magmas by melting of young subducted lithosphere. Nature 347(6294):662–665
Ding X, Lundstrom C, Huang F, Li J, Zhang ZM, Sun XM, Liang JL, Sun WD (2009) Natural and experimental constraints on formation of the continental crust based on niobium–tantalum fractionation. Int Geol Rev 51(6):473–501
Drummond MS, Defant MJ (1990) A model for trondhjemite–tonalite–dacite genesis and crustal growth via slab melting—archean to modern comparisons. J Geophys Res Solid 95(B13):21503–21521
Foley SF, Barth MG, Jenner GA (2000) Rutile/melt partition coefficients for trace elements and an assessment of the influence of rutile on the trace element characteristics of subduction zone magmas. Geochim Cosmochim Acta 64(5):933–938
Foley SF, Tiepolo M, Vannucci R (2002) Growth of early continental crust controlled by melting of amphibolite in subduction zones. Nature 417(6891):837–840
Gao J, John T, Klemd R, Xiong XM (2007) Mobilization of Ti–Nb–Ta during subduction: evidence from rutile-bearing dehydration segregations and veins hosted in eclogite, Tianshan, NW China. Geochim Cosmochim Acta 71(20):4974–4996
Gao CG, Liu YS, Zong KQ, Hu ZC, Gao S (2010) Microgeochemistry of rutile and zircon in eclogites from the CCSD main hole: implications for the fluid activity and thermo-history of the UHP metamorphism. Lithos 115(1–4):51–64
Grégoire MG, Bell DB, Le Roex ALR (2002) Trace element geochemistry of phlogopite-rich mafic mantle xenoliths: their classification and their relationship to phlogopite-bearing peridotites and kimberlites revisited. Contrib Mineral Petrol 142(5):603–625
Hart SR, Dunn T (1993) Experimental Cpx melt partitioning of 24 trace-elements. Contrib Mineral Petrol 113(1):1–8
Hauri EH, Wagner TP, Grove TL (1994) Experimental and natural partitioning of Th, U, Pb and other trace-elements between garnet, clinopyroxene and basaltic melts. Chem Geol 117(1–4):149–166
He YS, Li SG, Hoefs J, Huang F, Liu SA, Hou ZH (2011) Post-collisional granitoids from the Dabie orogen: new evidence for partial melting of a thickened continental crust. Geochim Cosmochim Acta 75(13):3815–3838
Hermann J (2002) Allanite: thorium and light rare earth element carrier in subducted crust. Chem Geol 192(3–4):289–306
Horng W-S, Hess PC (2000) Partition coefficients of Nb and Ta between rutile and anhydrous haplogranite melts. Contrib Mineral Petrol 138(2):176–185
Huang J, Xiao Y, Gao Y, Hou Z, Wu W (2012) Nb–Ta fractionation induced by fluid-rock interaction in subduction-zones: constraints from UHP eclogite- and vein-hosted rutile from the Dabie orogen, Central-Eastern China. J Metamorph Geol 30(8):821–842
Jahn BM (1998) Geochemical and isotopic characteristics of UHP eclogites and ultramafic rocks of the Dabie orogen. In: Hacker R, LiouWhen JG (eds) Continents collide: geochemistry of ultrahigh-pressure rocks. Kluwer Academic Publishing, Dordrecht, pp 203–239
Jahn BM, Rumble D, Liou JG (2003) Geochemistry and isotope tracer study of UHP metamorphic rocks. EMU Notes Mineral 5:365–414
Jochum KP, Nehring F (2006) NIST 610: GeoReM preferred values (11/2006) GeoReM http://georem.mpchmainz.gwdg.de
Kamber BS, Collerson KD (2000) Role of ‘hidden’ deeply subducted slabs in mantle depletion. Chem Geol 166:241–254
Karner JM, Papike JJ, Shearer CK, Mckay G, Le L, Burger P (2007) Valence state partitioning of Cr and V between pyroxene-melt: estimates of oxygen fugacity for martian basalt QUE 94201. Am Mineral 92(7):1238–1241
Kelemen PB, Shimizu N, Dunn T (1993) Relative depletion of niobium in some are magmas and the continental-crust—partitioning of K, Nb, La and Ce during melt/rock reaction in the upper-mantle. Earth Planet Sci Lett 120(3–4):111–134
Klemme S, Blundy JD, Wood BJ (2002) Experimental constraints on major and trace element partitioning during partial melting of eclogite. Geochim Cosmochim Acta 66(17):3109–3123
Klemme S, Prowatke S, Hametner K, Gunther D (2005) Partitioning of trace elements between rutile and silicate melts: implications for subduction zones. Geochim Cosmochim Acta 69(9):2361–2371
Klemme S, Guenther D, Hametner K, Prowatke S, Zack T (2006) The partitioning of trace elements between ilmenite, ulvospinel, annalcolite and silicate melts with implications for the early differentiation of the moon. Chem Geol 234(3–4):251–263
Konzett J, Armstrong RA, Günther D (2000) Modal metasomatism in the Kaapvaal craton lithosphere: constraints on timing and genesis from U–Pb zircon dating of metasomatized peridotites and MARID-type xenoliths. Contrib Mineral Petrol 139(6):704–719
Kretz R (1983) Symbols for rock-forming minerals. Am Mineral 68:277–279
Lee CTA, Brandon AD, Norman M (2003) Vanadium in peridotites as a proxy for paleo-fO(2) during partial melting: prospects, limitations, and implications. Geochim Cosmochim Acta 67(16):3045–3064
Liang JL, Ding X, Sun XM, Zhang ZM, Zhang H, Sun WD (2009) Nb/Ta fractionation observed in eclogites from the Chinese Continental Scientific Drilling Project. Chem Geol 268(1–2):27–40
Liou JG, Zhang RY, Jahn B (1997) Petrology, geochemistry and isotope data on a ultrahigh-pressure jadeite quartzite from Shuanghe, Dabie mountains, east-central China. Lithos 41(1–3):59–78
Liou JG, Zhang RY, Jahn BM (2000) Petrological and geochemical characteristics of ultrahigh-pressure metamorphic rocks from the Dabie-Sulu terrane, east-central China. Int Geol Rev 42(4):328–352
Liu FL, Xu Z, Katayama I, Yang J, Maruyama S, Liou JG (2001a) Mineral inclusions in zircons of para- and orthogneiss from pre-pilot drillhole CCSD-PP1, Chinese Continental Scientific Drilling Project. Lithos 59(4):199–215
Liu JB, Ye K, Maruyama SN, Cong BL, Fan HR (2001b) Mineral inclusions in zircon from gneisses in the ultrahigh-pressure zone of the Dabie Mountains, China. J Geol 109(4):523–535
Liu YS, Zong KQ, Kelemen PB, Gao S (2008) Geochemistry and magmatic history of eclogues and ultramafic rocks from the Chinese continental scientific drill hole: subduction and ultrahigh-pressure metamorphism of lower crustal cumulates. Chem Geol 247(1–2):133–153
Luvizotto GL, Zack T (2009) Nb and Zr behavior in rutile during high-grade metamorphism and retrogression: an example from the Ivrea-Verbano Zone. Chem Geol 261(3–4):303–317
Ma CQ, Ehlers C, Xu CH, Li ZC, Yang KG (2000) The roots of the Dabieshan ultrahigh-pressure metamorphic terrane: constraints from geochemistry and Nd–Sr isotope systematics. Precambrian Res 102(3–4):279–301
Malaspina N, Poli S, Fumagalli P (2009) The oxidation state of metasomatized mantle wedge: insights from C–O–H-bearing garnet peridotite. J Petrol 50(8):1533–1552
Mallmann G, O’Neill HSC (2009) The crystal/melt partitioning of v during mantle melting as a function of oxygen fugacity compared with some other elements (Al, P, Ca, Sc, Ti, Cr, Fe, Ga, Y, Zr and Nb). J Petrol 50(9):1765–1794
Marschall HR, Dohmen R, Ludwig T (2013) Diffusion-induced fractionation of niobium and tantalum during continental crust formation. Earth Planet Sc Lett 375(0):361–371
Martin H (1999) Adakitic magmas: modern analogues of Archaean granitoids. Lithos 46(3):411–429
McCammon C (2005) The paradox of mantle redox. Science 308(5723):807–808
McCammon C, Frost D, Smyth J, Laustsen H, Kawamoto T, Ross N, van Aken P (2004) Oxidation state of iron in hydrous mantle phases: implications for subduction and mantle oxygen fugacity. Phys Earth Planet Inter 143–144:157–169
Mcdonough WF, Sun SS (1995) The composition of the Earth. Chem Geol 120(3–4):223–253
Mungall JE (2002) Roasting the mantle: slab melting and the genesis of major Au and Au-rich Cu deposits. Geology 30(10):915–918
Münker C, Pfänder JA, Weye S, Buchl A, Kleine T, Mezger K (2003) Evolution of planetary cores and the earth-moon system from Nb/Ta systematics. Science 301(5629):84–87
Okay AI (1993) Petrology of a diamond and Coesite-bearing metamorphic terrain—Dabie Shan, China. Eur J Mineral 5(4):659–675
O’Neill HS (1987) Quartz-Fayalite-Iron and Quartz-Fayalite-Magnetite Equilibria and the Free-Energy of Formation of Fayalite (Fe2SiO4) and Magnetite (Fe3O4). Am Mineral 72(1–2):67–75
Parkinson IJ, Arculus RJ (1999) The redox state of subduction zones: insights from arc-peridotites. Chem Geol 160(4):409–423
Rapp RP, Shimizu N, Norman MD (2003) Growth of early continental crust by partial melting of eclogite. Nature 425(6958):605–609
Rudnick RL, Barth M, Horn I, McDonough WF (2000) Rutile-bearing refractory eclogites: missing link between continents and depleted mantle. Science 287(5451):278–281
Rumble D, Yui TF (1998) The Qinglongshan oxygen and hydrogen isotope anomaly near Donghai in Jiangsu Province, China. Geochim Cosmochim Acta 62(19–20):3307–3321
Ryerson FJ, Watson EB (1987) Rutile saturation in magmas: implications for Ti-Nb-Ta depletion in island-arc basalts. Earth Planet Sci Lett 86(2–4):225–239
Schmidt MW, Dardon A, Chazot G, Vannucci R (2004) The dependence of Nb and Ta rutile-melt partitioning on melt composition and Nb/Ta fractionation during subduction processes. Earth Planet Sci Lett 226(3–4):415–432
Schmidt A, Weyer S, John T, Brey GP (2009) HFSE systematics of rutile-bearing eclogites: new insights into subduction zone processes and implications for the earth’s HFSE budget. Geochim Cosmochim Acta 73(2):455–468
Shannon RD (1976) Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides. Acta Crystallogr A 32(5):751–767
Sheng YM, Zheng YF, Chen RX, Li Q, Dai M (2012) Fluid action on zircon growth and recrystallization during quartz veining within UHP eclogite: insights from U–Pb ages, O–Hf isotopes and trace elements. Lithos 136–139:126–144
Sun XM, Tang Q, Sun WD, Xu L, Zhai W, Liang JL, Liang YH, Shen K, Zhang ZM, Zhou B, Wang FY (2007) Monazite, iron oxide and barite exsolutions in apatite aggregates from CCSD drillhole eclogites and their geological implications. Geochim Cosmochim Acta 71:2896–2905
Sutton SR, Karner J, Papike J, Delaney JS, Shearer C, Newville M, Eng P, Rivers M, Dyar MD (2005) Vanadium K edge XANES of synthetic and natural basaltic glasses and application to microscale oxygen barometry. Geochim Cosmochim Acta 69(9):2333–2348
Triebold S, von Eynatten H, Luvizotto GL, Zack T (2007) Deducing source rock lithology from detrital rutile geochemistry: an example from the Erzgebirge, Germany. Chem Geol 244(3–4):421–436
Wade J, Wood BJ (2001) The Earth’s ‘missing’ niobium may be in the core. Nature 409(6816):75–78
Weyer S, Munker C, Mezger K (2003) Nb/Ta, Zr/Hf and REE in the depleted mantle: implications for the differentiation history of the crust-mantle system. Earth Planet Sci Lett 205(3–4):309–324
Xia Q-K, Liu J, Liu S-C, Kovács I, Feng M, Dang L (2013) High water content in Mesozoic primitive basalts of the North China Craton and implications on the destruction of cratonic mantle lithosphere. Earth Planet Sci Lett 361:85–97
Xiao YL, Hoefs J, van den Kerkhof AM, Fiebig J, Zheng YF (2000) Fluid history of UHP metamorphism in Dabie Shan, China: a fluid inclusion and oxygen isotope study on the coesite-bearing eclogite from Bixiling. Contrib Mineral Petrol 139(1):1–16
Xiao YL, Hoefs J, Van Den Kerkhof AM, Li SG (2001) Geochemical constraints of the eclogite and granulite facies metamorphism as recognized in the Raobazhai complex from North Dabie Shan, China. J Metamorph Geol 19(1):3–19
Xiao YL, Hoefs J, Van den Kerkhof AM, Simon K, Fiebig J, Zheng YF (2002) Fluid evolution during HP and UHP metamorphism in Dabie Shan, China: constraints from mineral chemistry, fluid inclusions and stable isotopes. J Petrol 43(8):1505–1527
Xiao YL, Zhang ZM, Hoefs J, van den Kerkhof A (2006a) Ultrahigh-pressure metamorphic rocks from the Chinese Continental Scientific Drilling Project: II oxygen isotope and fluid inclusion distributions through vertical sections. Contrib Mineral Petrol 152(4):443–458
Xiao YL, Sun WD, Hoefs J, Simon K, Zhang ZM, Li SG, Hofmann AW (2006b) Making continental crust through slab melting: constraints from niobium-tantalum fractionation in UHP metamorphic rutile. Geochim Cosmochim Acta 70(18):4770–4782
Xiong XL, Adam J, Green TH (2005) Rutile stability and rutile/melt HFSE partitioning during partial melting of hydrous basalt: implications for TTG genesis. Chem Geol 218(3–4):339–359
Xiong XL, Keppler H, Audetat A, Ni HW, Sun WD, Li YA (2011) Partitioning of Nb and Ta between rutile and felsic melt and the fractionation of Nb/Ta during partial melting of hydrous metabasalt. Geochim Cosmochim Acta 75(7):1673–1692
Xu ST, Okay AI, Ji SY, Sengor AMC, Wen S, Liu YC, Jiang LL (1992) Diamond from the dabie-shan metamorphic rocks and its implication for tectonic setting. Science 256(5053):80–82
Zack T, Kronz A, Foley SF, Rivers T (2002) Trace element abundances in rutiles from eclogites and associated garnet mica schists. Chem Geol 184(1–2):97–122
Zack T, Moraes R, Kronz A (2004a) Temperature dependence of Zr in rutile: empirical calibration of a rutile thermometer. Contrib Mineral Petrol 148(4):471–488
Zack T, von Eynatten H, Kronz A (2004b) Rutile geochemistry and its potential use in quantitative provenance studies. Sediment Geol 171(1–4):37–58
Zhang ZM, Xu Z, Liu F, You Z, Shen K, Yang J, Li T, Chen S (2004) Geochemistry of eclogites from the main hole (100-2050 m) of the Chinese Continental Scientific Drilling Project. Acta Petrology Sinica 20(1):27–42 (in Chinese with English Abstract)
Zhang Z, Shen K, Xiao Y, Hoefs J, Liou JG (2006a) Mineral and fluid inclusions in zircon of UHP metamorphic rocks from the CCSD-main drill hole: a record of metamorphism and fluid activity. Lithos 92(3–4):378–398
Zhang ZM, Liou JG, Zhao XD, Shi C (2006b) Petrogenesis of Maobei rutile eclogites from the southern Sulu ultrahigh-pressure metamorphic belt, eastern China. J Metamorph Geol 24(8):727–741
Zhang Z-M, Shen K, Sun W-D, Liu Y-S, Liou JG, Shi C, Wang J-L (2008) Fluids in deeply subducted continental crust: petrology, mineral chemistry and fluid inclusion of UHP metamorphic veins from the Sulu orogen, eastern China. Geochim Cosmochim Acta 72(13):3200–3228
Zhang RY, Iizuka Y, Ernst WG, Liou JG, Xu ZQ, Tsujimori T, Lo CH, Jahn BM (2009) Metamorphic P-T conditions and thermal structure of Chinese Continental Scientific Drilling main hole eclogites: Fe-Mg partitioning thermometer vs. Zr-in-rutile thermometer. J Metamorph Geol 27(9):757–772
Zhang ZM, Shen K, Liou JG, Dong X, Wang W, Yu F, Liu F (2011) Fluid-rock interactions during UHP metamorphism: a review of the Dabie-Sulu orogen, east-central China. J Asian Earth Sci 42(3):316–329
Zhao DG, Essene EJ, Zhang YX (1999) An oxygen barometer for rutile-ilmenite assemblages: oxidation state of metasomatic agents in the mantle. Earth Planet Sci Lett 166(3–4):127–137
Zheng YF (2009) Fluid regime in continental subduction zones: petrological insights from ultrahigh-pressure metamorphic rocks. J Geol Soc Lond 166:763–782
Zheng YF, Zhao ZF, Wu YB, Zhang SB, Liu X, Wu FY (2006) Zircon U–Pb age, Hf and O isotope constraints on protolith origin of ultrahigh-pressure eclogite and gneiss in the Dabie orogen. Chem Geol 231(1–2):135–158
Zheng YF, Gao XY, Chen RX, Gao TS (2011) Zr-in-rutile thermometry of eclogite in the Dabie orogen: constraints on rutile growth during continental subduction-zone metamorphism. J Asian Earth Sci 40(2):427–451
Zong KQ, Liu YS, Liu XM, Zhang BH (2006) In situ trace element geochemistry of single minerals in eclogites from the CCSD main hole(100–1100 m). Acta Petrologica Sinica 22(7):1891–1904 (in Chinese with English abstract)
Acknowledgments
This study was supported by funds from the Natural Science Foundation of China (41172067, 41090372 and 41273037). We are grateful to Profs. Stephan Klemme, Xiaolin Xiong and Guilherme Mallmann for their discussion on the Nb and V partitioning between rutile and melt as well as the dependence of V partitioning on fO2, which considerably improved the manuscript. We give special thanks to Prof. G. Wörner for proof reading the manuscript and polishing the language. We are further indebted to two anonymous reviewers of the present version for their very detailed and constructive comments.
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Liu, L., Xiao, Y., Aulbach, S. et al. Vanadium and niobium behavior in rutile as a function of oxygen fugacity: evidence from natural samples. Contrib Mineral Petrol 167, 1026 (2014). https://doi.org/10.1007/s00410-014-1026-2
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DOI: https://doi.org/10.1007/s00410-014-1026-2