Different Origins of the Fractionation of Platinum-Group Elements in Raobazhai and Bixiling Mafic-Ultramafic Rocks from the Dabie Orogen, Central China
Concentrations of the platinum group elements (PGEs), including Ir, Ru, Rh, Pt, and Pd, have been determined for both Raobazhai and Bixiling mafic-ultramafic rocks from the Dabie Orogen by fire assay method. Geochemical compositions suggest that the Raobazhai mafic-ultramafic rocks represent mantle residues after variable degrees of partial melting. They show consistent PGE patterns, in which the IPGEs (i.e., Ir and Ru) are strongly enriched over the PPGEs (i.e., Pt and Pd). Both REE and PGE data of the Raobazhai mafic-ultramafic rocks suggest that they have interacted with slab-derived melts during subduction and/or exhumation. The Bixiling ultramafic rocks were produced through fractional crystallization and cumulation from magmas, which led to the fractionated PGE patterns. During fractional crystallization, Pd is in nonsulfide phases, whereas both Ir and Ru must be compatible in some mantle phases. We suggest that the PGE budgets of the ultramafic rocks could be fractionated by interaction with slab-derived melts and fractional crystallization processes. 1. Introduction The platinum group elements (PGEs), including Os, Ir, Ru, Rh, Pt, and Pd, are strongly siderophile and chalcophile elements. They have similar geochemical behaviors during magmatic processes. Traditionally, the PGEs are subdivided into two groups, the compatible IPGEs (Os, Ir, and Ru) and the incompatible PPGEs (Rh, Pd, and Pt) [1]. It has been suggested that the IPGEs are refractory and tend to be retained in the mantle peridotites during partial melting [2]. In contrast, the PPGEs are concentrated in the base metal sulphides (e.g., pentlandite, chalcopyrite), which are released to the melts along with the molten sulfide melts [2]. Because of their unique geochemical characteristics, the PGEs can be used to identify the magma sources and unravel the complex petrogenetic processes, such as partial melting, melt percolation, and metasomatism in the mantle [1]. Mafic-ultramafic rocks have lower REE contents but higher PGE contents than other rocks, so the PGEs have advantages in studying their petrogenetic processes [1, 3–7]. In this study, we present the PGE data of both Raobazhai and Bixiling mafic-ultramafic rocks from Dabie Orogen, central China, to discuss their fractionation behaviours during magma evolution. The mechanisms of differentiation between these elements will be examined below, taking into account the geochemical affinities of the PGE and their partition in the mineral phases. The results also demonstrate that the PGEs can provide important information on the genesis
References
[1]
S. J. Barnes, R. Boyd, and A. Korneliussen , “The use of mantle normalization and metal ratios in discriminating between the effects of partial melting, crystal fractionation and sulphide segregation on platinum-group elements, gold, nickel and copper: examples from Norway,” in Proceedings of the Geo-Platinum Conference, H. M. Prichard, J. W. Bowles, and P. Potts, Eds., pp. 113–143, Elsevier, Amsterdam, The Netherlands, 1988.
[2]
R. R. Keays, “The role of komatiitic and picritic magmatism and S-saturation in the formation of ore deposits,” Lithos, vol. 34, no. 1–3, pp. 1–18, 1995.
[3]
S. J. Barnes, A. J. Naldrett, and M. P. Gorton, “The origin of the fractionation of platinum-group elements in terrestrial magmas,” Chemical Geology, vol. 53, no. 3-4, pp. 303–323, 1985.
[4]
J. P. Lorand, “Abundance and distribution of CuFeNi sulfides, sulfur, copper and platinum-group elements in orogenic-type spinel lherzolite massifs of Ariège (Northeastern Pyrenees, France),” Earth and Planetary Science Letters, vol. 93, no. 1, pp. 50–64, 1989.
[5]
G. Garuti, C. Gorgoni, and G. P. Sighinolfi, “Sulfide mineralogy and chalcophile and siderophile element abundances in the Ivrea-Verbano mantle peridotites (Western Italian Alps),” Earth and Planetary Science Letters, vol. 70, no. 1, pp. 69–87, 1984.
[6]
G. Garuti, G. Fershtater, F. Bea, P. Montero, E. V. Pushkarev, and F. Zaccarini, “Platinum-group elements as petrological indicators in mafic-ultramafic complexes of the central and southern Urals: preliminary results,” Tectonophysics, vol. 276, no. 1–4, pp. 181–194, 1997.
[7]
M. Rehk？mper, A. N. Halliday, J. G. Fitton, D. C. Lee, M. Wieneke, and N. T. Arndt, “Ir, Ru, Pt, and Pd in basalts and komatiites: new constraints for the geochemical behavior of the platinum-group elements in the mantle,” Geochimica et Cosmochimica Acta, vol. 63, no. 22, pp. 3915–3934, 1999.
[8]
B. M. Jahn, F. Wu, C. H. Lo, and C. H. Tsai, “Crust-mantle interaction induced by deep subduction of the continental crust: geochemical and Sr-Nd isotopic evidence from post-collisional mafic-ultramafic intrusions of the northern Dabie complex, central China,” Chemical Geology, vol. 157, no. 1-2, pp. 119–146, 1999.
[9]
S. S. Sun and W. F. McDonough, “Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes,” Magmatism in the Ocean Basins, pp. 313–345, 1989.
[10]
B. R. Hacker, L. Ratschbacher, L. Webb et al., “Exhumation of ultrahigh-pressure continental crust in east central China: late Triassic-Early Jurassic tectonic unroofing,” Journal of Geophysical Research B, vol. 105, no. 6, pp. 13339–13364, 2000.
[11]
J. Zheng, M. Sun, M. F. Zhou, and P. Robinson, “Trace elemental and PGE geochemical constraints of Mesozoic and Cenozoic peridotitic xenoliths on lithospheric evolution of the North China Craton,” Geochimica et Cosmochimica Acta, vol. 69, no. 13, pp. 3401–3418, 2005.
[12]
S. J. Barnes and C. P. Picard, “The behaviour of platinum-group elements during partial melting, crystal fractionation, and sulphide segregation: an example from the Cape Smith Fold Belt, northern Quebec,” Geochimica et Cosmochimica Acta, vol. 57, no. 1, pp. 79–87, 1993.
[13]
B. R. Hacker, L. Ratschbacher, L. Webb, T. Ireland, D. Walker, and D. Shuwen, “U/Pb zircon ages constrain the architecture of the ultrahigh-pressure Qinling-Dabie Orogen, China,” Earth and Planetary Science Letters, vol. 161, no. 1–4, pp. 215–230, 1998.
[14]
X. Yang, “A cold ultramafic intrusive body in Dabieshan area, Anhui Province,” Bulletin of Nanjing Institute of Geology, vol. 4, pp. 81–95, 1983.
[15]
S. Xu, L. Jiang, Y. Liu, and Y. Zhang, “Tectonic framework and evolution of the Dabie Mountains in Anhui, eastern China,” Acta Geologica Sinica, vol. 5, pp. 221–238, 1992.
[16]
C. H. Tsai, J. C. Liou, and W. G. Ernst, “Petrological characterization and tectonic significance of retrogressed garnet peridotites, Raobazhai area, North Dabie Complex, east-central China,” Journal of Metamorphic Geology, vol. 18, no. 2, pp. 181–192, 2000.
[17]
Q. Zhang, B. Ma, R. Liu et al., “A remnant of continental lithospheric mantle above subduction zone: geochemical constraints on ultramafic rock from Raobazhai area, Anhui province,” Science in China Series B, vol. 38, no. 12, pp. 1522–1529, 1995.
[18]
X. C. Zhi, Y. B. Jin, Q. Meng, and T. S. Gao, “Trace element geochemistry of Raobazhai ultramafic complex, North Dabie Mountain,” Acta Petrologica Sinica, vol. 20, no. 3, pp. 463–472, 2004.
[19]
R. Y. Zhang, J. G. Liou, and B. L. Cong, “Ultrahigh-pressure metamorphosed talc-, magnesite- and Ti-clinohumite-bearing mafic–ultramafic complex, Dabie mountains, east-central China,” Journal of Petrology, vol. 36, no. 4, pp. 1011–1037, 1995.
[20]
V. Chavagnac and B. M. Jahn, “Coesite-bearing eclogites from the Bixiling Complex, Dabie Mountains, China: Sm-Nd ages, geochemical characteristics and tectonic implications,” Chemical Geology, vol. 133, no. 1–4, pp. 29–51, 1996.
[21]
H. Downes, “Formation and modification of the shallow sub-continental lithospheric mantle: a review of geochemical evidence from ultramatic xenolith suites and tectonically emplaced ultramafic massifs of Western and Central Europe,” Journal of Petrology, vol. 42, no. 1, pp. 233–250, 2001.
[22]
K. Gueddari, M. Piboule, and J. Amossé, “Differentiation of platinum-group elements (PGE) and of gold during partial melting of peridotites in the lherzolitic massifs of the Betico-Rifean range (Ronda and Beni Bousera),” Chemical Geology, vol. 134, no. 1–3, pp. 181–197, 1996.
[23]
J. W. Morgan, “Ultramafic xenoliths: clue to the earth’s late accretionary history,” Journal of Geophysical Research, vol. 91, pp. 12375–12387, 1986.
[24]
J. P. Lorand, L. Pattou, and M. Gros, “Fractionation of Platinum-group elements and gold in the upper mantle: a detailed study in Pyrenean orogenic lherzolites,” Journal of Petrology, vol. 40, no. 6, pp. 957–981, 1999.
[25]
W. F. McDonough and F. A. Frey, “Rare earth elements in upper mantle rocks,” in Geochemistry and Mineralogy of the Rare Earth Elements, B. R. Lipin and G. A. McKay, Eds., vol. 21, pp. 99–145, Mineralogical Society of America, 1989.
[26]
R. Y. Zhang, D. Rumble, J. G. Liou, and Q. C. Wang, “Low δ18O, ultrahigh-P garnet-bearing mafic and ultramafic rocks from Dabie Shan, China,” Chemical Geology, vol. 150, no. 1-2, pp. 161–170, 1998.
[27]
P. Kepezhinskas, M. J. Defant, and E. Widom, “Abundance and distribution of PGE and Au in the island-arc mantle: implications for sub-arc metasomatism,” Lithos, vol. 60, no. 3-4, pp. 113–128, 2002.
[28]
G. E. Brügmann, N. T. Arndt, A. W. Hofmann, and H. J. Tobschall, “Noble metal abundances in komatiite suites from Alexo, Ontario and Gorgona Island, Colombia,” Geochimica et Cosmochimica Acta, vol. 51, no. 8, pp. 2159–2169, 1987.
[29]
J. P. Lorand, R. R. Keays, and J. L. Bodinier, “Copper and noble metal enrichments across the lithosphere-asthenosphere boundary of mantle diapirs: evidence from the lanzo lherzolite massif,” Journal of Petrology, vol. 34, no. 6, pp. 1111–1140, 1993.
[30]
J. J. Standish, S. R. Hart, J. Blusztajn, H. J. B. Dick, and K. L. Lee, Abyssal peridotite osmium isotopic composition for Cr-spinel, Geochem. Geophys. Geosyst. 2001GG000161, 2001.
[31]
M. Rehk？mper, A. N. Halliday, J. Alt, J. G. Fitton, J. Zipfel, and E. Takazawa, “Non-chondritic platinum-group element ratios in oceanic mantle lithosphere: petrogenetic signature of melt percolation?” Earth and Planetary Science Letters, vol. 172, no. 1-2, pp. 65–81, 1999.
[32]
J. E. Snow and G. Schmidt, “Constraints on Earth accretion deduced from noble metals in the oceanic mantle,” Nature, vol. 391, no. 6663, pp. 166–169, 1998.
[33]
A. Büchl, G. Brügmann, V. G. Batanova, C. Münker, and A. W. Hofmann, “Melt percolation monitored by Os isotopes and HSE abundances: a case study from the mantle section of the Troodos Ophiolite,” Earth and Planetary Science Letters, vol. 204, no. 3-4, pp. 385–402, 2002.
[34]
J. P. Lorand, L. Reisberg, and R. M. Bedini, “Platinum-group elements and melt percolation processes in Sidamo spinel peridotite xenoliths, Ethiopia, East African Rift,” Chemical Geology, vol. 196, no. 1–4, pp. 57–75, 2003.
[35]
J. P. Lorand, G. Delpech, M. Grégoire, B. Moine, S. Y. O'Reilly, and J. Y. Cottin, “Platinum-group elements and the multistage metasomatic history of Kerguelen lithospheric mantle (South Indian Ocean),” Chemical Geology, vol. 208, no. 1–4, pp. 195–215, 2004.
[36]
J. P. Lorand, A. Luguet, O. Alard, A. Bezos, and T. Meisel, “Abundance and distribution of platinum-group elements in orogenic lherzolites; a case study in a Fontete Rouge lherzolite (French Pyrénées),” Chemical Geology, vol. 248, no. 3-4, pp. 174–194, 2008.
[37]
L. Reisberg, X. Zhi, J. P. Lorand, C. Wagner, Z. Peng, and C. Zimmermann, “Re-Os and S systematics of spinel peridotite xenoliths from east central China: evidence for contrasting effects of melt percolation,” Earth and Planetary Science Letters, vol. 239, no. 3-4, pp. 286–308, 2005.
[38]
H. Becker, M. F. Horan, R. J. Walker, S. Gao, J. P. Lorand, and R. L. Rudnick, “Highly siderophile element composition of the Earth's primitive upper mantle: constraints from new data on peridotite massifs and xenoliths,” Geochimica et Cosmochimica Acta, vol. 70, no. 17, pp. 4528–4550, 2006.
[39]
L. Ackerman, R. J. Walker, I. S. Puchtel, L. Pitcher, E. Jelínek, and L. Strnad, “Effects of melt percolation on highly siderophile elements and Os isotopes in subcontinental lithospheric mantle: a study of the upper mantle profile beneath Central Europe,” Geochimica et Cosmochimica Acta, vol. 73, no. 8, pp. 2400–2414, 2009.
[40]
Y. Xiao and H.-F. Zhang, “Effects of melt percolation on platinum group elements and Re-Os systematics of peridotites from the Tan-Lu fault zone, eastern North China Craton,” Journal of the Geological Society, vol. 168, no. 5, pp. 1201–1214, 2011.
[41]
M. J. Defant and M. S. Drummond, “Derivation of some modern arc magmas by melting of young subducted lithosphere,” Nature, vol. 347, no. 6294, pp. 662–665, 1990.
[42]
M. S. Drummond, M. J. Defant, and P. K. Kepezhinskas, “Petrogenesis of slab-derived trondhjemite-tonalite-dacite/adakite magmas,” Transactions of the Royal Society of Edinburgh, Earth Sciences, vol. 87, no. 1-2, pp. 205–215, 1996.
[43]
H. Martin, “Adakitic magmas: modern analogues of Archaean granitoids,” Lithos, vol. 46, no. 3, pp. 411–429, 1999.
[44]
L. Zheng, X. Zhi, and L. Reisberg, “Re-Os systematics of the Raobazhai peridotite massifs from the Dabie orogenic zone, eastern China,” Chemical Geology, vol. 268, no. 1-2, pp. 1–14, 2009.
[45]
S.-J. Barnes and W. D. Maier, “The fractionation of Ni, Cu, and the noble metals in silicate and sulphide liquids,” in Dynamic Processes in Magmatic Ore Deposits and Their Application in Mineral Exploration, R. R. Keays, Ed., Short Course Notes 13, pp. 69–106, Geological Association Canada, 1999.
[46]
W. Yi, A. N. Halliday, J. C. Alt et al., “Cadmium, indium, tin, tellurium, and sulfur in oceanic basalts: implications for chalcophile element fractionation in the Earth,” Journal of Geophysical Research B, vol. 105, no. 8, pp. 18927–18948, 2000.
[47]
G. E. Brügmann, N. T. Arndt, A. W. Hofmann, and H. J. Tobschall, “Noble metal abundances in komatiite suites from Alexo, Ontario and Gorgona Island, Colombia,” Geochimica et Cosmochimica Acta, vol. 51, no. 8, pp. 2159–2169, 1987.
[48]
M. F. Zhou, “PGE distribution in 2.7-Ga layered komatiite flows from the Belingwe greenstone belt, Zimbabwe,” Chemical Geology, vol. 118, no. 1–4, pp. 155–172, 1994.
[49]
I. O. Oshin and J. H. Crocket, “Noble metals in Thetford Mines ophiolites, Quebec, Canada—part I: distribution of gold, iridium, platinum, and palladium in the ultramafic and gabbroic rocks,” Economic Geology, vol. 77, no. 6, pp. 1556–1570, 1982.
[50]
C. J. Capobianco, R. L. Hervig, and M. J. Drake, “Experiments on crystal/liquid partitioning of Ru, Rh and Pd for magnetite and hematite solid solutions crystallized from silicate melt,” Chemical Geology, vol. 113, no. 1-2, pp. 23–43, 1994.
[51]
C. Ballhaus, “Is the upper mantle metal-saturated?” Earth and Planetary Science Letters, vol. 132, no. 1–4, pp. 75–86, 1995.
[52]
R. J. Walker, E. Hanski, J. Vuollo, and J. Liipo, “The Os isotopic composition of Proterozoic upper mantle: evidence for chondritic upper mantle from the Outokumpu ophiolite, Finland,” Earth and Planetary Science Letters, vol. 141, no. 1–4, pp. 161–173, 1996.
[53]
M. Tredoux, N. M. Lindsay, G. Davies, and I. McDonald, “The fractionation of platinum-group elements in magmatic systems, with the suggestion of a novel causal mechanism,” South African Journal of Geology, vol. 98, no. 2, pp. 157–167, 1995.
[54]
C. Ballhaus and P. Sylvester, “Spatial platinum-group-element distribution in magmatic sulfides: implications for the platinum group-element behavior during mantle melting,” in Proceedings of the 7th Annual V.M. Goldschmidt Conference, pp. 15–16, 1997.
