Abstract
This paper reports the results of a geochemical investigation of zircon from a migmatized aluminous gneiss (gn), melanosome (M), and sequential leucosome generations (Lc2, Lc3, Lc4, and Lc5) from an outcrop in the northwestern Ladoga region. The contents of REE, Y, Ti, Hf, Th, U, and P were determined using a Cameca IMS-4f ion microprobe in 12 zircon grains from the aforementioned rocks, in two-three spots in each grain. All of the specimens show rather uniform REE distribution patterns. More significant variations were observed in the light and medium REE (at smaller variations in the heavy REE), as well as in Ti, Y, Th, and U contents between zircons from the host rocks and from the leucosomes. It was supposed that REE-rich zircons from the gneiss and melanosome (without oscillatory zoning) are relics, whereas rhythmically zoned zircons with lower REE contents crystallized in the gneiss in the presence of dispersed anatectic melt. The contents of most REE and Y increase from core to rim in zircons from the gneiss, melanosome, Lc2, Lc4, and Lc5, which is opposite to the compositional trend of zircons from Lc3. It was shown that the decrease of HREE and Y content in zircon in the sequence Lc5 → gn → Lc2, Lc3, Lc4 is related to a decrease in the abundance of these elements in the rocks. The leucosomes do not correspond to a differentiation series of a single melt (there is no variation trends of Rb/Sr, K/Rb, and Rb/Ba in the rock series). The lower Lu/Hf and Sm/Nd values in the leucosomes relative to the host rocks allowed us to suppose that their protolith was gneisses (for Lc2) and migmatites (for Lc4 and Lc3). The similarity of the early migmatites and gneisses to Lc3 with respect to major and some trace elements and almost identical Lu/Hf and Sm/Nd values support the possibility of the formation of this leucosome generation during the beginning of the diatexis of migmatites, which was promoted by a temperature increase. This resulted in a specific trend in the content of some elements during zircon growth in Lc3, which is different from the trend of zircons from other leucosomes.
Similar content being viewed by others
References
F. Bea, M. D. Pereira, and A. Stroh, “Mineral/Leucosoma Trace-Element Partitioning in a Peraluminous Migmatite (a Laser Ablation-ICP-MS Study),” Chem. Geol. 117, 291–312 (1994).
F. Bea, “Residence of REE, Y, Th, and U in Granites and Crustal Protoliths; Implications for the Chemistry of Crustal Melts,” J. Petrol. 37(3), 521–552 (1996).
G. Varva, R. Schmid, and D. Gebauer, “Internal Morphology, Habit and U-Th-Pb Microanalysis of Amphibolite-to-Granulite Facies Zircons: Geochronology of the Ivrea Zone (Southern Alps),” Contrib. Mineral. Petrol. 134, 380–404 (1999).
E. A. Belousova, W. L. Griffin, and S. Y. O’Reily, “Zircon Crystal Morphology, Trace Element Signatures and Hf Isotope Composition As a Tool for Petrogenetic Modelling: Examples from Eastern Australian Granitoids,” J. Petrol. 47(2), 329–353 (2006).
P. W. O. Hoskin and U. Schaltegger, “Composition of Zircon and Igneous and Metamorphic Petrogenesis,” Rev. Mineral. Geochem. 53, 27–62 (2003).
D. Rubatto, “Zircon Trace Element Geochemistry: Partitioning with Garnet and the Link between U-Pb Ages and Metamorphism,” Chem. Geol. 184, 123–138 (2002).
Geology and Petrology of the Svecofennides of the Ladoga Region, Ed. by V. A. Glebovitsky (St. Petersburg Univ., St. Petersburg, 2000) [in Russian].
I. S. Sedova, L. M. Samorukova, V. A. Glebovitskii, and D. P. Krylov, “Geochemistry of Granitoids of the Svecofennian Tectonometamorphic Cycle in the Northern Ladoga Region,” Petrologiya 12(4), 394–414 (2004) [Petrology 12, 348–366 (2004)].
Migmatization and Granite Formation in Different Thermodynamic Regimes, Ed. by F. P. Mitrofanov (Nauka, Leningrad, 1985) [in Russian].
Sh. K. Baltybaev, O. A. Levchenkov, N. G. Berezhnaya, et al., “Age and Duration of Svecofennian Plutono-Metamorphic Activity in the Ladoga Area, Southeastern Baltic Shield,” Petrologiya 12(4), 373–393 (2004) [Petrology 12, 330–347 (2004)].
Sh. K. Baltybaev, O. A. Levchenkov, V. A. Glebovitskii, et al., “Duration of Migmatite Formation in the Granulite-Facies Metamorphism Zone of Svecofennides of the Ladoga Region, Southeastern Baltic Shield,” Dokl. Akad. Nauk 406(6), 797–800 (2006) [Dokl. Earth Sci. 406, 271–274 (2006)].
V. I. Shuldiner, Sh. K. Baltybaev, and I. V. Kozyreva, “Metamorphic Evolution of Garnet-Bearing Granulites in the Western Ladoga Area,” Petrologiya 5, 253–277 (1997) [Petrology 5, 223–245 (1997)].
A. N. Neelov, Petrochemical Classification of Metamorphosed Sedimentary and Volcanic Rocks (Nauka, Leningrad, 1980) [in Russian].
W. V. Boynton, “Cosmochemistry of the Rare Earth Elements Meteorite Studies,” in Rare Earth Element Geochemistry (Amsterdam, 1984), pp. 63–114.
R. W. Hinton and B. G. Upton, “The Chemistry of Zircon: Variations within and Between Large Crystals from Syenite and Basalt Xenoliths,” Geochim. Cosmochim. Acta 55, 3287–3302 (1991).
E. B. Watson and T. M. Harrison, “Zircon Saturation Revisited: Temperature Compositional Effects in a Variety of Crustal Magma Types,” Earth Planet. Sci. Lett. 64, 295–304 (1983).
F. Corvu, J. M. Hanchar, P. W. O. Hoskin, and P. Kinny, “Atlas of Zircon Textures,” Rev. Mineral. Geochem. 53, 469–500 (2003).
U. Poller, J. Huth, P. Hoppe, and I. S. Williams, “REE, U, Th, and Hf Distribution in Zircon from Western Carpathian Variscan Granitoids: A Combined Cathodoluminescence and Ion Microprobe Study,” Am. J. Sci. 301, 858–876 (2001).
S. G. Skublov, Geochemistry of Rare Earth Elements in Rock-Forming Metamorphic Minerals (Nauka, St. Petersburg, 2005) [in Russian].
X. Wang, W. L. Griffin, S. Y. O’Reily, et al., “Morphology and Geochemistry of Zircons from Late Mesozoic Igneous Complexes in Coastal SE China: Implications for Petrogenesis,” Mineral. Mag. 66(2), 235–251 (2002).
P. Barbey, P. Alle, M. Brouand, and F. Albarede, “Rare-Earth Patterns in Zircons from the Manaslu Granite and Tibetan Slab Migmatites (Himalaya): Insights in the Origin and Evolution of a Crustally-Derived Granite Magma,” Chem. Geol. 125, 1–17 (1995).
D. Rubatto, I. S. Williams, and I. S. Buick, “Zircon and Monazite Response to Prograde Metamorphism in the Reynolds Range, Central Australia,” Contrib. Mineral. Petrol. 140, 458–468 (2001).
V. A. Glebovitskii and I. S. Sedova, “Anatexis and Formation of Crustal Magmatic Chambers: Petrological and Geological Evidence (Belomorian and Svecofennian Province, Baltic Shield),” Zap. Vseross. Mineral. O-va 42(3), 487–505 (1998).
I. Milord, E. W. Sawyer, and M. Brown, “Formation of Diatexite Migmatite and Granite Magma during Anatexis of Semi-Pelitic Metasedimentary Rocks: An Example from St. Malo, France,” J. Petrol. 42(3), 487–505 (2001).
Author information
Authors and Affiliations
Corresponding author
Additional information
Original Russian Text © I.S. Sedova, L.M. Samorukova, V.A. Glebovitskii, S.G. Skublov, 2009, published in Geokhimiya, 2009, No. 10, pp. 1050–1066.
Rights and permissions
About this article
Cite this article
Sedova, I.S., Samorukova, L.M., Glebovitskii, V.A. et al. Zircon from the polymigmatites of the northwestern Ladoga region: Morphology and geochemistry. Geochem. Int. 47, 988–1003 (2009). https://doi.org/10.1134/S0016702909100048
Received:
Published:
Issue Date:
DOI: https://doi.org/10.1134/S0016702909100048