On the enigma of Nb-Ta and Zr-Hf fractionation—A critical review

Abstract

Elemental ratios Zr/Hf and Nb/Ta are expected to be constant and of chondritic value (∼36.30 and ∼17.57, respectively) in mantle and mantle-derived rocks. Studies in recent years have shown, however, that these two ratios do vary in some of these rocks. For example, MORB-like seamount lavas from flanks of the East Pacific Rise (EPR) show a correlated Zr/Hf (∼25–50) and Nb/Ta (∼9–18) variation. These two ratios are also correlated with ratios of more incompatible over less incompatible elements (e.g., La/Sm, Rb/Cs, Th/U, Nb/U, Sm/Yb) and with radiogenic isotope ratios (e.g., ⁸⁷Sr/⁸⁶Sr, ¹⁴³Nd/¹⁴⁴Nd). Furthermore, abyssal peridotites, which are melting residues for MORB, also show a huge correlated variation between Zr/Hf (∼2.5–335) and Nb/Ta (∼1–170). All these observations plus a correlated variation between Zr/Hf (∼22–48) and Nb/Ta (∼10–23) in lunar rocks are consistent with the Zr-Hf and Nb-Ta fractionation being of magmatic origin. This contrasts with the common view that geochemical processes cannot readily fractionate them. As charges and ionic radii are the principal factors in the general theory of elemental fractionation, this theory cannot explain the fractionation of these two element pairs with the same charges (i.e., 5⁺ for Nb and Ta, and 4⁺ for Zr and Hf) and essentially the same ionic size (i.e., R _Nb/R _Ta=1.000, R _Zr/R _Hf=1.006 to ∼1.026 for coordination numbers of 6, 7, 8 and 12). We explore the possibilities of other factors and processes (e.g., mass-dependent fractionation during magmatism) that may cause the observed Nb-Ta and Zr-Hf fractionation. We emphasize that understanding the correlated Nb-Ta and Zr-Hf fractionation “known” to take place during magmatism is fundamental for improved understanding of elemental fractionations through other earth processes in various tectonic environments, including the origin and evolution of continental crust, which has a characteristic subchondritic Nb/Ta value of ∼11-12.

Keywords

Nb/Ta / Zr/Hf / correlated variation / magmatic process / mass-dependent fractionation

References

[1] Aulbach S., O’Reilly S. Y., Griffin W. L., . Sub continental Lithospheric Mantle Origin of High Niobium/Tantalum Ratios in Eclogites. Nature Geoscience, 2008, 1(7): 468-472.

[2] Blundy J., Wood B.. Prediction of Crystal-Melt Partition Coefficients from Elastic Moduli. Nature, 1994, 372(6505): 452-454.

[3] Blundy J., Wood B.. Partitioning of Trace Elements between Crystals and Melts. Earth and Planetary Science Letters, 2003, 210(3–4): 383-397.

[4] Bougault, H., Joron, J. L., Treuil, M., 1979. Alteration, Fractional Crystallization, Partial Melting, Mantle Properties from Trace Elements in Basalts Recovered in the North Atlantic. In: Talwani, M., Harrison, C. G., Hayes, D. E., eds., Deep Drilling Results in the North Atlantic Ocean Crust. Maurice Ewing Series, 2: 352–368

[5] Brenan J. M., Shaw H. F., Ryerson F. J., . Mineral-Aqueous Fluid Partitioning of Trace Elements at 900 °c and 2.0 GPa: Constraints on the Trace Element Chemistry of Mantle and Deep Crustal Fluids. Geochimica et Cosmochimica Acta, 1995, 59(16): 3331-3350.

[6] Brice J. C.. Some Thermodynamic Aspects of the Growth of Strained Crystals. Journal of Crystal Growth, 1975, 28(2): 249-253.

[7] Dautria J. M., Dupuy C., Takherist D., . Carbonate Metasomatism in the Lithospheric Mantle: Peridotitic Xenoliths from a Melilititic District of the Sahara Basin. Contributions to Mineralogy and Petrology, 1992, 111(1): 37-52.

[8] Dupuy C., Liotard J. M., Dostal J.. Zr-Hf Fractionation in Intraplate Basaltic Rocks: Carbonate Metasomatism in the Mantle Source. Geochimica et Cosmochimica Acta, 1992, 56(6): 2417-2423.

[9] Elliott T., Plank T., Zindler A., . Element Transport from Slab to Volcanic Front at the Mariana Arc. Journal of Geophysical Research, 1997, 102(B7): 14991-15019.

[10] Fábio R. D. d. A., Möller P., Dulski P.. Zr-Hf in Carbonatites and Alkaline Rocks: New Data and a Re-evaluation. Revista Brasileira de Geociencias, 2002, 32(3): 361-370.

[11] Foley S. F., Barth M. G., Jenner G. A.. Rutile/Melt Partition Coefficients for Trace Elements and an Assessment of the Influence of Rutile on the Trace Element Characteristics of Subduction Zone Magmas. Geochimica et Cosmochimica Acta, 2000, 64(5): 933-938.

[12] Foley S., Tiepolo M., Vannucci R.. Growth of Early Continental Crust Controlled by Melting of Amphibolite in Subduction Zones. Nature, 2002, 417(6891): 837-840.

[13] Gao J., John T., Klemd R., . Mobilization of Ti-Nb-Ta during Subduction: Evidence from Rutile-Bearing Dehydration Segregations and Veins Hosted in Eclogite, Tianshan, NW China. Geochimica et Cosmochimica Acta, 2007, 71(20): 4974-4996.

[14] Goldschmidt V. M.. The Principles of Distribution of Chemical Elements in Minerals and Rocks. J. Chem. Soc., 1937, 140: 655-673.

[15] Green T. H.. Significance of Nb/Ta as an Indicator of Geochemical Processes in the Crust-Mantle System. Chemical Geology, 1995, 120: 347-359.

[16] Green T. H., Blundy J. D., Adam J., . SIMS Determination of Trace Element Partition Coefficients between Garnet, Clinopyroxene and Hydrous Basaltic Liquids at 2–7.5 GPa and 1 080–1 200 °C. Lithos, 2000, 53(3–4): 165-187.

[17] Hofmann A. W.. Chemical Differentiation of the Earth: The Relationship between Mantle, Continental Crust, and Oceanic Crust. Earth and Planetary Science Letters, 1988, 90(3): 297-314.

[18] Hofmann A. W.. Mantle Geochemistry: The Message from Oceanic Volcanism. Nature, 1997, 385(6613): 219-229.

[19] Hofmann A. W., Jochum K. P., Seufert M., . Nb and Pb in Oceanic Basalts: New Constraints on Mantle Evolution. Earth and Planetary Science Letters, 1986, 79(1–2): 33-45.

[20] Huang X. L., Wang R. C., Chen X. M., . Vertical Variations in the Mineralogy of the Yichun Topaz-Lepidolite Granite, Jiangxi Province, Southern China. The Canadian Mineralogist, 2002, 40: 1047-1068.

[21] Jochum K. P., Seufert H. M., Spettel B., . The Solar-System Abundances of Nb, Ta, Y and the Relative Abundances of Refractory Lithophile Elements in Differentiated Planetary Bodies. Geochimica et Cosmochimica Acta, 1986, 50(6): 1173-1183.

[22] Klein C., Hurlbut C. S.. Manual of Mineralogy (after James D. Dana), 1999, New York, NY, United States: John Wiley & Sons 596

[23] Klemme S., Blundy J. D., Wood B. J.. Experimental Constraints on Major and Trace Element Partitioning during Partial Melting of Eclogite. Geochimica et Cosmochimica Acta, 2002, 66(17): 3109-3123.

[24] Kogiso T., Tatsumi Y., Nakano S.. Trace Element Transport during Dehydration Processes in the Subducted Oceanic Crust: 1, Experiments and Implications for the Origin of Ocean Island Basalts. Earth and Planetary Sci ence Letters, 1997, 148(1–2): 193-205.

[25] Linnen R. L., Keppler H.. Melt Composition Control of Zr/Hf Fractionation in Magmatic Processes. Geochimica et Cosmochimica Acta, 2002, 66(18): 3293-3301.

[26] McDonough W. F., Sun S. S.. The Composition of the Earth. Chemical Geology, 1995, 120(3–4): 223-253.

[27] Mo X. X., Niu Y. L., Dong G. C., . Contribution of Syncollisional Felsic Magmatism to Continental Crust Growth: A Case Study of the Paleogene Linzizong Volcanic Succession in Southern Tibet. Chemical Geology, 2008, 250(1–4): 49-67.

[28] Muenker C., Pfaender J. A., Weyer S., . Evolution of Planetary Cores and the Earth-Moon System from Nb/Ta Systematics. Science, 2003, 301(5629): 84-87.

[29] Nagasawa H.. Trace Element Partition Coefficient in Ionic Crystals. Science, 1966, 152(3723): 767-769.

[30] Niu Y. L.. Bulk-Rock Major and Trace Element Compositions of Abyssal Peridotites: Implications for Mantle Melting, Melt Extraction and Post-Melting Processes beneath Mid-Ocean Ridges. Journal of Petrology, 2004, 45(12): 2423-2458.

[31] Niu Y. L.. Generation and Evolution of Basaltic Magmas: Some Basic Concepts and a New View on the Origin of Mesozoic-Cenozoic Basaltic Volcanism in Eastern China. Geological Journal of China Universities, 2005, 11(1): 9-46.

[32] Niu Y. L., Batiza R.. Trace Element Evidence from Seamounts for Recycled Oceanic Crust in the Eastern Pacific Mantle. Earth and Planetary Science Letters, 1997, 148(3–4): 471-483.

[33] Niu Y. L., Hekinian R.. Basaltic Liquids and Harzburgitic Rresidues in the Garrett Transform: A Case Study at Fast-Spreading Ridges. Earth and Planetary Science Letters, 1997, 146(1–2): 243-258.

[34] Niu Y. L., O’Hara M. J.. The Origin of Ocean Island Basalts (OIB): A New Perspective from Petrology, Geochemistry and Mineral Physics Considerations. Journal of Geophysical Research, 2003, 108(B4): 1-19.

[35] Niu Y. L., O’Hara M. J.. MORB Mantle Hosts the Missing Eu (Sr, Nb, Ta and Ti) in the Continental Crust: New Perspectives on Crust-Mantle Differentiation and Chemical Structure of Oceanic Upper Mantle. Lithos, 2009, 112(1–2): 1-17.

[36] Niu Y. L., Regelous M., Wendt I. J., . Geochemistry of Near-EPR Seamounts: Importance of Source vs. Process and the Origin of Enriched Mantle Component. Earth and Planetary Science Letters, 2002, 199(3–4): 327-345.

[37] Norton D. L., Dutrow B. L.. Complex Behavior of Magma-Hydrothermal Processes: Role of Supercritical Fluid. Geochimica et Cosmochimica Acta, 2001, 65(21): 4009-4017.

[38] Onuma N., Higuchi H., Wakita H., . Trace Element Partition between Two Pyroxenes and the Host Lava. Earth and Planetary Science Letters, 1968, 5(1): 47-51.

[39] Palme H., O’Neill H. St. C.. Cosmochemical Estimates of Mantle Composition. Treatise on Geochemistry, 2003, 2: 1-38.

[40] Pfaender J. A., Muenker C., Stracke A., . Nb/Ta and Zr/Hf in Ocean Island Basalts-Implications for Crust-Mantle Differentiation and the Fate of Niobium. Earth and Planetary Science Letters, 2007, 254(1–2): 158-172.

[41] Ringwood A. E.. The Principles Governing Trace Element Distribution during Magmatic Crystallization-Part I: The Influence of Electronegativity. Geochimica et Cosmochimica Acta, 1955, 7(3–4): 189-202.

[42] Rollinson H.. Using Geochemical Data: Evaluation, Presentation, Interpretation. Longman Scientific & Technical, 1993, New York: John Wiley & Sons 352

[43] Rudnick R. L., Barth M., Horn I., . Rutile-Bearing Refractory Eclogites: Missing Link between Continents and Depleted Mantle. Science, 2000, 287(5451): 278-281.

[44] Rudnick R. L., Fountain D. M.. Nature and Composition of the Continental Crust: A Lower Crustal Perspective. Review of Geophysics, 1995, 33(3): 267-309.

[45] Rudnick R. L., Gao S.. Composition of the Continental Crust. Treatise on Geochemistry, 2003, 3: 1-64.

[46] Shannon R. D.. Revised Effective Ionic Radii and Systematic Studies of Interatomic Distances in Halides and Chalcogenides. Acta Cryst., A, 1976, 32: 751-767.

[47] Speer J. A., Cooper B. J.. Crystal Structure of Synthetic Hafnon, HfSiO4, Comparison with Zircon and the Actinide Orthosilicates. American Mineralogist, 1982, 67: 804-808.

[48] Sun S. S., McDonough W. F.. Chemical and Isotopic Systematics in Ocean Basalts: Implications for Mantle Composition and Processes. Geological Society Special Publications, 1989, 42: 313-345.

[49] Tatsumi Y., Hamilton D. L., Nesbitt R. W.. Chemical Characteristics of Fluid Phase Released from a Subducted Lithosphere and Origin of Arc Magmas: Evidence from High-Pressure Experiments and Natural Rocks. Journal of Volcanology and Geothermal Research, 1986, 29(1–4): 293-309.

[50] Taylor S. R.. The Origin and Growth of Continents. Tec tonophysics, 1967, 4(1): 17-34.

[51] Taylor S. R.. Talwani M., Pitman W. C. III. Island Arc Models and the Composition of the Continental Crust. Island Arcs, Deep Sea Trenches, and Back-Arc Basins, 1977, Washington, D.C.: American Geophysical Union 325 335

[52] Taylor S. R., McLennan S. M.. The Continental Crust: Its Composition and Evolution, 1985, Oxford: Blackwell 312

[53] Tiepolo M., Vannucci R., Oberti R., . Nb and Ta Incorporation and Fractionation in Titanian Pargasite and Kaersutite: Crystal-Chemical Constraints and Implications for Natural Systems. Earth and Planetary Science Letters, 2000, 176(2): 185-201.

[54] Wade J., Wood B. J.. The Earth’s ‘Missing’ Niobium may be in the Core. Nature, 2001, 409(6816): 75-78.

[55] Wang R. C., Fontan F., Xu S. J., . Hafnian Zircon from the Apical Part of the Suzhou Granite, China. The Canadian Mineralogist, 1996, 34: 1001-1010.

[56] Wang R. C., Zhao G. T., Lu J. J., . Chemistry of Hf-Rich Zircons from the Laoshan I- and A-Type Granites, Eastern China. Mineralogical Magazine, 2000, 64: 867-877.

[57] Wanke H., Palme H., Baddenhausen H., . New Data on the Chemistry of Lunar Samples: Primary Matter in the Lunar Highlands and the Bulk Composition of the Moon. Pro. Lunar Sci., 1975, 6: 1313-1340.

[58] Weyer S., Munker C., Mezger K.. Nb/Ta, Zr/Hf and REE in the Depleted Mantle: Implications for the Differentiation History of the Crust-Mantle System. Earth and Planetary Science Letters, 2003, 205(3–4): 309-324.

[59] Wood B. J., Blundy J. D.. A Predictive Model for Rare Earth Element Partitioning between Clinopyroxene and Anhydrous Silicate Melt. Contributions to Mineralogy and Petrology, 1997, 129(2–3): 166-181.

[60] Workman R. K., Hart S. R.. Major and Trace Element Composition of the Depleted MORB Mantle (DMM). Earth and Planetary Science Letters, 2005, 231(1–2): 53-72.

[61] Xiao Y. L., Sun W. D., Hoefs J., . Making Continental Crust through Slab Melting: Constriants from Niobium-Tantalum Fractionation in UHP Metamorphic Rutile. Geochimica et Cosmochimica Acta, 2006, 70(18): 4770-4782.

[62] Zhang A. C., Wang R. C., Hu H., . Chemical Evolution of Nb-Ta Oxides and Zircon from the Koktokay No.3 Granitic Pegmatite, Altai, Northwestern China. Mineralogical Magazine, 2004, 68: 739-756.