Advertisement

Nb–Ta fractionation by partial melting at the titanite–rutile transition

Abstract

During the evolution of the Earth, distinct geochemical reservoirs with different Nb/Ta ratios have developed. Archean granitoids of the tonalite–trondhjemite–granodiorite (TTG) suite, which represent the Earth’s early continental crust, show larger Nb/Ta variations than any other Earth reservoir. This implies that significant Nb–Ta fractionation must have occurred during early crust formation, while the underlying mechanism behind is still unclear. Here, we present a new model on how Nb may be fractionated from Ta during partial melting of subducted oceanic crust. Our data show that Nb/Ta ratios in melts derived from rutile- and titanite-bearing eclogite are largely controlled by the modal relative abundances of rutile and titanite in the source. High modal ratios of titanite over rutile generate melts with very high Nb/Ta (>60), whereas low modal titanite/rutile produces melts with much lower Nb/Ta (≤30). Very low Nb/Ta (<16) occur when all Ti-phases are consumed at very high degrees of melting. As the modal ratio of titanite to rutile is a function of pressure, the Nb/Ta of melts is a function of melting depth. Our new model helps to explain the extreme variation of Nb/Ta observed in many TTGs and thus how Nb and Ta were fractionated during the early evolution of the Earth. Furthermore, the model also indicates that simple one-stage melting models for mafic crust are not sufficient to explain the formation of TTGs.

This is a preview of subscription content, log in to check access.

Access options

Buy single article

Instant unlimited access to the full article PDF.

US$ 39.95

Price includes VAT for USA

Subscribe to journal

Immediate online access to all issues from 2019. Subscription will auto renew annually.

US$ 199

This is the net price. Taxes to be calculated in checkout.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9

References

  1. Arth JG, Hanson GN (1972) Quartz diorites derived by partial melting of eclogites or amphibolite at mantle depths. Contrib Mineral Petrol 37:161–174

  2. Barth MG, McDonough WF, Rudnick RL (2000) Tracking the budget of Nb and Ta in the continental crust. Chem Geol 165:197–213

  3. Barth MG, Foley SF, Horn I (2002) 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 113:323–340

  4. Beinlich A, Klemd R, John T, Gao J (2010) Trace element mobilization during Ca-metasomatism along a major fluid conduit: eclogitization of blueschist as a consequence of fluid–rock interaction. Geochim Cosmochim Acta 74:1892–1922

  5. Bernau R, Franz G (1987) Crystal chemistry and genesis of Nb-, V-, and Al-rich metamorphic titanite from Egypt and Greece. Can Mineral 25:695–705

  6. 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 267:301–308

  7. Carswell DA, Wilson RN, Zhai M (1996) Ultra-high pressure aluminous titantites in carbonate-bearing eclogites at Shuanghe in Dabieshan, central China. Mineral Mag 60:461–471

  8. Connolly JAD (1990) Multivariable phase diagrams; an algorithm based on generalized thermodynamics. Am J Sci 290:666–718

  9. Connolly JAD, Podladchikov YY (2007) Decompaction weakening and channeling instability in ductile porous media: Implications for asthenospheric melt segregation. J Geophys Res 112:1–15

  10. DeVries RC, Roy R, Osborn EF (1955) Phase equilibria in the system CaO–TiO2–SiO2. J Am Ceram Soc 38:158–171

  11. El Korh A, Schmidt ST, Ulianov A, Potel S (2009) Trace element partitioning in HP-LT metamorphic assemblages during subduction-related metamorphism, Ile de Groix, France: a detailed LA-ICPMS study. J Petrol 50:1107–1148

  12. Evans BW (1990) Phase relations of epidote-blueschists. Lithos 25:3–23

  13. Foley S, Tiepolo M, Vannucci R (2002) Growth of early continental crust controlled by melting of amphibolite in subduction zones. Nature 417:837–840

  14. Frost BR, Chamberlain KR, Schumacher JC (2000) Sphene (titanite): phase relations and role as a geochronometer. Chem Geol 172:131–148

  15. Gaetani GA, Asimow PD, Stolper EM (2008) A model for rutile saturation in silicate melts with applications to eclogite partial melting in subduction zones and mantle plumes. Earth Planet Sci Lett 272:720–729

  16. Gao J, Klemd R (2001) Primary fluids entrapped at blueschist to eclogite transition: evidence from the Tianshan meta-subduction complex in northwestern China. Contrib Mineral Petrol 142:1–14

  17. Gao J, Klemd R (2003) Formation of HP-LT rocks and their tectonic implications in the western Tianshan Orogen, NW China; geochemical and age constraints. Lithos 66:1–22

  18. Gao J, Klemd R, Zhang L, Wang Z, Xiao X (1999) PT path of high-pressure/low-temperature rocks and tectonic implications in the western Tianshan Mountains, NW China. J Metamorph Geol 17:621–636

  19. Green TH (1995) Significance of Nb/Ta as an indicator of geochemical processes in the crust-mantle system. Chem Geol 120:347–359

  20. Green TH, Pearson NJ (1986a) Rare-earth element partitioning between sphene and coexisting silicate liquid at high-pressure and temperature. Chem Geol 55:105–119

  21. Green TH, Pearson NJ (1986b) Ti-rich accessory phase saturation in hydrous mafic-felsic compositions at high P, T. Chem Geol 54:185–201

  22. Hoffmann JE et al (2009) The origin of TTGs inferred from high-precision HFSE measurements. Geochim Cosmochim Acta 73:A540

  23. Hofmann AW (1988) Chemical differentiation of the Earth; the relationship between mantle, continental crust, and oceanic crust. Earth Planet Sci Lett 90:297–314

  24. John T, Klemd R, Gao J, Garbe-Schönberg C-D (2008) Trace-element mobilization in slabs due to non steady-state fluid–rock interaction: Constraints from an eclogite-facies transport vein in blueschist (Tianshan, China). Lithos 103:1–24

  25. King RL, Bebout GE, Kobayashi K, Nakamura E, van der Klauw SNGC (2004) Ultrahigh-pressure metabasaltic garnets as probes into deep subduction zone chemical cycling. Geochem Geophys Geosyst 5:Q12J14. doi:10.1029/2004GC000746

  26. Klein M, Stosch H-G, Seck HA (1997) Partitioning of high field-strength and rare-earth elements between amphibole and quartz-dioritic to tonalitic melts: an experimental study. Chem Geol 138:257–271

  27. Klemd R, Schröter FC, Will TM, Gao J (2002) PT evolution of glaucophane-omphacite bearing HP-LT rocks in the western Tianshan Orogen, NW China; new evidence for “Alpine-type” tectonics. J Metamorph Geol 20:239–254

  28. Klemme S, Blundy JD, Wood BJ (2002) Experimental constraints on major and trace element partitioning during partial melting of eclogite. Geochim Cosmochim Acta 66:3109–3312

  29. Klemme S, Prowatke S, Hametner K, Günther D (2005) Partitioning of trace elements between rutile and silicate melts: Implications for subduction zones. Geochim Cosmochim Acta 69:2361–2371

  30. Klemme S et al (2008) Synthesis and preliminary characterisation of new silicate, phosphate and titanite reference glasses. J Geostand. Geoanal. 32:39–54

  31. Klimm K, Blundy JD, Green TH (2008) Trace element partitioning and accessory phase saturation during H2O-saturated melting of basalt with implications for subduction zone chemical fluxes. J Petrol 49:523–553

  32. 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 268:27–40

  33. Lü Z, Zhang LF, Du J, Bucher K (2008) Coesite inclusions in garnet from eclogitic rocks in western Tianshan, northwest China: Convincing proof of UHP metamorphism. Am Mineral 93:1845–1850

  34. Lü Z, Zhang LF, Du J, Bucher K (2009) Petrology of coesite-bearing eclogite from Habutengsu Valley, western Tianshan, NW China and its tectonometamorphic implication. J Metamorph Geol 27:773–787

  35. Lucassen F, Dulski P, Abart R, Franz G, Rhede D, Romer RL (2010) Redistribution of HFSE elements during rutile replacement by titanite. Contrib Mineral Petrol. doi:10.1007/s00410-009-0477-3

  36. Luvizotto GL et al (2009) Rutile crystals as potential trace element and isotope mineral standards for microanalysis. Chem Geol 261:346–369

  37. Manning CA, Bohlen SR (1991) The reaction Titanite + Kyanite = Anorthite + Rutile and Titanite–Rutile barometry in eclogites. Contrib Mineral Petrol 109:1–9

  38. Münker C, Pfänder JA, Weyer S, Büchl A, Kleine T, Mezger K (2003) Evolution of planetary cores and the Earth–Moon system from Nb/Ta systematics. Science 301:84–87

  39. Paul BJ, Cerny P, Chapman R (1981) Niobian titanite from the Huron Claim Pegmatite, southeastern Manitoba. Can Mineral 19:549–552

  40. Peacock SM, Wang K (1999) Seismic consequences of warm versus cool subduction metamorphism: examples from Southwest and Northeast Japan. Science 286:937–939

  41. Peacock SM, Rushmer T, Thompson AB (1994) Partial melting of subducting oceanic crust. Earth Planet Sci Lett 121:227–244

  42. Pearce NJG, Perkins WT, Westgate JA, Gorton MP, Jackson SE, Neal CR, Chenery SP (1997) A compilation of new and published major and trace element data for NIST SRM 610 and NIST SRM 612 glass reference materials. Geostand Newslett 21:115–144

  43. Pertermann M, Hirschmann MM (2003) Anhydrous partial melting experiments on MORB-like eclogite: Phase relations, phase compositions and mineral-melt partitioning of major elements at 2–3 GPa. J Petrol 44:2173–2201

  44. Pertermann M, Hirschmann MM, Hametner K, Günther D, Schmidt MW (2004) Experimental determination of trace element partitioning between garnet and silica-rich liquid during anhydrous partial melting of MORB-like eclogite Geochem Geophys Geosyst 5:2003GC000638

  45. Pfänder JA, Münker C, Stracke A, Mezger K (2007) Nb/Ta and Zr/Hf in ocean island basalts—implications for crust–mantle differentiation and the fate of Niobium. Earth Planet Sci Lett 254:158–172

  46. Prowatke S, Klemme S (2005) Effect of melt composition on the partitioning of trace elements between titanite and silicate melt. Geochim Cosmochim Acta 69:695–709

  47. Rapp RP, Shimizu N, Norman MD (2003) Growth of early continental crust by partial melting of eclogite. Nature 425:605–609

  48. Rudnick RL, Barth M, Horn I, McDonough WF (2000) Rutile-bearing refractory eclogites: missing link between continents and depleted mantle. Science 287:278–281

  49. Schmidt MW, Poli S (1998) Experimentally based water budgets for dehydrating slabs and consequences for arc magma generation. Earth Planet Sci Lett 163:361–379

  50. 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 226:415–432

  51. 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 73:455–468

  52. Sen C, Dunn T (1994) Dehydration melting of a basaltic composition amphibolite at 1.5 and 2.0 GPa: implications for the origin of adakites. Contrib Mineral Petrol 117:394–409

  53. Storkey AC, Hermann J, Hand M, Buick IS (2005) Using in situ trace-element determinations to monitor partial-melting processes in metabasites. J Petrol 46:1283–1308

  54. Su W, Gao J, Klemd R, Li J, Zhang X, Li X, Chen N, Zhang L (2010) U–Pb zircon geochronology of Tianshan eclogites in NW China: implication for the collision between the Yili and Tarim blocks of the southwestern Altaids. Eur J Mineral (in press)

  55. Tiepolo M, Oberti R, Vannucci R (2002) Trace-element incorporation in titanite: constraints from experimentally determined solid/liquid partition coefficients. Chem Geol 191:105–119

  56. Troitzsch U, Ellis DJ (2002) Thermodynamic properties and stability of AlF-bearing titanite CaTiOSiO4–CaAlFSiO4. Contrib Mineral Petrol 142:543–563

  57. Tropper P, Manning CE (2008) The current status of titanite–rutile thermobarometry in ultrahigh-pressure metamorphic rocks: the influence of titanite activity models on phase equilibrium calculations. Chem Geol 254:123–132

  58. Tropper P, Manning CE, Essene EJ (2002) The substitution of Al and F in titanite at high pressure and temperature: Experimental constraints on phase relations and solid solution properties. J Petrol 43:1787–1814

  59. van der Straaten F, Schenk V, John T, Gao J (2008) Blueschist-facies rehydration of eclogites (Tian Shan, NW-China): Implications for fluid–rock interaction in the subduction channel. Chem Geol 255:195–219

  60. van Thienen P, Vlaar NJ, van den Berg AP (2004) Plate tectonics on the terrestrial planets. Phys Earth Planet Inter 142:61–74

  61. Wade J, Wood BJ (2001) The Earth’s ‘missing’ niobium may be in the core. Nature 409:75–78

  62. Wang Q, Wyman DA, Zhao ZH, Xu JF, Bai ZH, Xiong XL, Dai TM, Li CF, Chu ZY (2007) Petrogenesis of Carboniferous adakites and Nb-enriched arc basalts in the Alataw area, northern Tianshan Range (western China): implications for Phanerozoic crustal growth in the Central Asia orogenic belt. Chem Geol 236:42–64

  63. Wei C, Powell R, Zhang L (2003) Eclogites from the south Tienshan, NW China: petrological characteristic and calculated mineral equilibria in the Na2O–CaO–FeO–MgO–Al2O3–SiO2–H2O system. J Metamorph Geol 21:163–179

  64. Xiong XL (2006) Trace element evidence for growth of early continental crust by melting of rutile-bearing hydrous eclogite. Geology 34:945–948

  65. 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 218:339–359

  66. Xiong X, Keppler H, Audetat A, Gudfinnsson G, Sun W, Song M, Xiao W, Yuan L (2009) Experimental constraints on rutile saturation during partial melting of metabasalt at the amphibolite to eclogite transition, with applications to TTG genesis. Am Mineral 94:1175–1186

  67. Zack T, Moraes R, Kronz A (2004) Temperature dependence of Zr in rutile: empirical calibration of a rutile thermometer. Contrib Mineral Petrol 148:1–18

Download references

Acknowledgments

This study was partly funded by the DFG (KL 692/17-2). H. Brätz is thanked for help with the LA-ICP-MS analyses. We would also like to acknowledge the discussions at the Institut für Mineralogie at the Universität Münster, in particular with K. Mezger, and thank C. Münker for his support. G. Franz and M. Barth are thanked for their helpful reviews, which clearly helped to improve our contribution, and our thanks also go to J. Hoefs for his swift editorial handling of the manuscript.

Author information

Correspondence to Timm John.

Additional information

Communicated by J. Hoefs.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

John, T., Klemd, R., Klemme, S. et al. Nb–Ta fractionation by partial melting at the titanite–rutile transition. Contrib Mineral Petrol 161, 35–45 (2011) doi:10.1007/s00410-010-0520-4

Download citation

Keywords

  • Crustal evolution
  • Nb–Ta
  • Partial melting
  • Rutile
  • Titanite
  • Subduction zone
  • Eclogite