Abstract
The bimodal volcanoplutonic (basalt-peralkaline rhyolite with peralkaline granites) association of the Noen and Tost ranges was formed 318 Ma ago in the Gobi-Tien Shan rift zone of the Late Paleozoic-Early Mesozoic central Asian rift system, the development of which was related to the movement of the continental lithosphere over a mantle hot spot. A specific feature of the Late Paleozoic rifting was that it occurred within the Middle-Late Paleozoic active continental margin of the northern Asian paleocontinent. Continental margin magmatism was followed after a short time delay by the magmatism of the Gobi-Tien Shan rift zone, which was located directly in the margin of the paleocontinent. Such a geodynamic setting of the rift zone was reflected in the geochemical characteristics of rift-related rocks. The distribution of major elements and compatible trace elements in the rift-related basic and intermediate rocks corresponds to a crystallization differentiation series. The distribution of incompatible trace elements suggests contributions from several sources. This is also supported by the heterogeneity of Sr and Nd isotopic compositions of the rift-related basaltoids: εNd(T) ranges from 4.4 to 6.7, and (87Sr/86Sr)0, from 0.70360 to 0.70427. The geochemical characteristics of the rift-related basaltoids of the Noen and Tost ranges are not typical of rift settings (negative anomalies in Nb and Ta and positive anomalies in K and Pb) and suggest a significant role of the rocks of a metasomatized mantle wedge in their source. In addition, there are high-titanium rocks among the rift-related basaltoids, whose geochemical characteristics approach those of the basalts of mid-ocean ridges and ocean islands. This allowed us to conclude that the compositional variations of the rift-related basaltoids of the Noen and Tost ranges were controlled by three magma sources: the enriched mantle, depleted mantle (high-titanium basaltoids), and metasomatized mantle wedge (medium-Ti basaltoids). The medium-titanium basaltoids were formed in equilibrium with spinel peridotites, whereas the high-titanium magmas were formed at deeper levels both in the spinel and garnet zones. It terms of geodynamics, the occurrence of three sources of the rift-related basaltoids of the Noen and Tost ranges was related to the ascent of a mantle plume with enriched geochemical characteristics beneath a continental margin, where its influence caused melting in the overlying depleted mantle and the metasomatized mantle wedge. The formation of rift-related andesites in the Noen and Tost ranges was explained by the contamination of mantle-derived basaltoid melts with sialic (mainly sedimentary) continental crustal materials or the assimilation of anatectic granitoid melts.
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References
A. I. Al’mukhamedov, A. Ya. Medvedev, and V. V. Zolotukhin, “Chemical Evolution of the Permian-Triassic Basalts of the Siberian Platform in Space and Time,” Petrologiya 12, 339–353 (2004) [Petrology 12, 297–310 (2004)].
F. Barberi, G. Ferrara, R. Santacrose, et al., “Transitional Basalt-Pantellerite Sequence of Fractional Crystallization, the Boina Centre (Afar Rift, Ethiopia),” J. Petrol. 16, 22–56 (1975).
L. Civetta, M. D’Antonio, G. Orsi, and G. R. Tilton, “The Geochemistry of Volcanic Rocks from Pantelleria Island, Sicily Channel: Petrogenesis and Characteristics of the Mantle Source Region,” J. Petrol. 39, 1453–1491 (1998).
G. R. Davies and R. Macdonald, “Crustal Influences in the Petrogenesis of the Naivasha Basalt-Comendite Complex: Combined Trace Element and Sr-Nd-Pb Isotope Constraints,” J. Petrol. 28, 1009–1031 (1987).
A. Ewart, J. S. Marsh, S. C. Milner, et al., “Petrology and Geochemistry of Early Cretaceous Bimodal Continental Flood Volcanism of the NW Etendeka, Namibia. Part 1: Introduction, Mafic Lavas and Re-Evaluation of Mantle Source Components,” J. Petrol. 45, 59–105 (2004).
G. L. Farmer, “Continental Basaltic Rocks,” in Treatise on Geochemistry, Ed. By L. R. Rudnick (Elsevier, 2003), Vol. 3, pp. 85–121.
V. A. Fedorenko, “Results of New Field and Geochemical Studies of the Volcanic and Intrusive Rocks of the Maymecha-Kotuy Area, Siberian Flood Basalt Province, Russia,” Int. Geol. Rev. 39, 353–479 (1997).
V. A. Fedorenko, P. C. Lightfoot, A. J. Naldrett, et al., “Petrogenesis of the Flood-Basalt Sequence of Norilsk, North Central Siberia,” Int. Geol. Rev. 38, 99–135 (1996).
T. Furman, J. G. Bryce, J. Karson, and A. Iotti, “East African Rift System (EARS) Plume Structure: Insights from Quaternary Mafic Lavas of Turkana, Kenya,” J. Petrol. 45, 1069–1088 (2004).
I. V. Gordienko, Paleozoic Magmatism and Geodynamics of the Central Asian Fold Belt (Nauka, Moscow, 1987) [in Russian].
T. H. Green, “Significance of Nb/Ta as an Indicator of Geochemical Processes in the Crust-Mantle System,” Chem. Geol. 120, 347–359 (1995).
P. B. Kelemen, K. Hanghoj, and A. R. Greene, “One View of the Geochemistry of Subduction-Related Magmatic Arcs, with an Emphasis on Primitive Andesite and Lower Crust,” in Treatise on Geochemistry, Ed. By R. L. Rudnick (Elsevier, 2003), Vol. 3, pp. 593–659.
P. B. Kelemen, N. Shimizu, and T. Dunn, “Relative Depletion of Niobium in Some Arc Magmas and the Continental Crust: Partitioning of K, Nb, La and Ce during Melt/Rock Reaction in Upper Mantle,” Earth Planet. Sci. Lett. 120, 11–134 (1993).
E. M. Klein, “Geochemistry of the Igneous Oceanic Crust,” in Treatise on Geochemistry, Ed. By R. L. Rudnick (Elsevier, 2003), Vol. 3, pp. 433–463.
V. I. Kovalenko, V. V. Yarmolyuk, E. B. Sal’nikova, et al., “Sources of Igneous Rocks and Genesis of the Early Mesozoic Tectonomagmatic Area of the Mongolia-Transbaikalia Magmatic Region: 2. Petrology and Geochemistry,” Petrologiya 11, 227–254 (2003) [Petrology 11, 205–229 (2003)].
A. M. Kozlovsky, V. V. Yarmolyuk, E. B. Sal’nikova, et al., “Age of Bimodal and Alkali Granite Magmatism of the Gobi-Tien Shan Rift Zone, Tost Range, Southern Mongolia,” Petrologiya 13, 232–239 (2005) [Petrology 13, 197–204 (2005)].
M. J. Le Bas, R. W. Le Maitre, A. Streckeisen, and B. A. Zanettin, “Chemical Classification of Volcanic Rocks Based on the Total Alkali-Silica Diagram,” J. Petrol. 27, 745–750 (1986).
R. Macdonald, N. W. Rogers, J. G. Fitton, et al., “Plume-Lithosphere Interactions in the Generation of the Basalts of the Kenya Rift, East Africa,” J. Petrol. 42, 877–900 (2001).
M. T. McCulloch and J. A. Gamble, “Geochemical and Geodynamical Constraints on Subduction Zone Magmatism,” Earth Planet. Sci. Lett. 102, 358–374 (1991).
H. Palme and H. St. C. O’Neill, “Cosmochemical Estimates of Mantle Composition,” in Treatise on Geochemistry, Ed. by R. W. Carlson (Elsevier, 2003), Vol. 2, pp. 1–38.
A. Peccerillo, M. R. Barberio, G. Yirgu, et al., “Relationships between Mafic and Peralkaline Silicic Magmatism in Continental Rift Settings: A Petrological, Geochemical and Isotopic Study of the Gedemsa Volcano, Central Ethiopian Rift,” J. Petrol. 44, 2003–2032 (2003).
B. G. Pokrovskii, Crustal Contamination of Mantle Magmas (Nauka, Moscow, 2000) [in Russian].
N. Rogers, R. Macdonald, J. G. Fitton, et al., “Two Mantle Plumes beneath the East African Rift System: Sr, Nd and Pb Isotope Evidence from Kenya Rift Basalts,” Earth Planet. Sci. Lett. 176, 387–400 (2000).
V. M. Savatenkov, I. M. Morozova, and L. K. Levskii, “Behavior of the Sm-Nd, Rb-Sr, K-Ar, and U-Pb Isotopic Systems during Alkaline Metasomatism: Fenites in the Outer-Contact Zone of an Ultramafic-Alkaline Intrusion,” Geokhimiya, No. 10, 1027–1049 (2004) [Geochem. Int. 42, 899–920 (2004)].
S. S. Sun and W. F. McDonough, “Chemical and Isotopic Systematics of Oceanic Basalts: Implications for Mantle Composition and Processes,” in Magmatism in the Ocean Basins, Ed. by A. D. Saunders and M. J. Norry, Geol. Soc. London. Spec. Publ. 42, 313–346 (1989).
S. R. Taylor and S. M. McLennan, The Continental Crust: Its Composition and Evolution (Blackwell, Oxford, 1985; Mir, Moscow, 1988).
Tectonics, Magmatism, and Metallogeny of Mongolia, Ed. by A. B. Dergunov (Routledge, London and New York, 2001).
T. Trua, C. Daniel, and R. Mazzuoli, “Crustal Control in the Genesis of Plio-Quaternary Bimodal Magmatism of the Main Ethiopian Rift (MER): Geochemical and Isotopic (Sr, Nd, Pb) Evidence,” Chem. Geol. 155, 201–231 (1999).
N. V. Vladykin, V. I. Kovalenko, and M. D. Dorfman, Mineralogical and Geochemical Features of the Haan Bogd Alkaline Granitoid Massif, Mongolia (Nauka, Moscow, 1981) [in Russian].
K. Wang, T. Plank, J. D. Walker, and E. I. Smith, “A Mantle Melting Profile across the Basin and Range, SW USA,” J. Geophys. Res. 107(B1), 10.1029/2001JB000209 (2002).
V. V. Yarmolyuk, Upper Paleozoic Volcanogenic Associations and Structural-Petrological Features of Their Evolution (Nauka, Moscow, 1978) [in Russian].
V. V. Yarmolyuk, Late Paleozoic Volcanism in the Continental Riftogenic Structures of Central Asia (Nauka, Moscow, 1983) [in Russian].
V. V. Yarmolyuk and V. I. Kovalenko, Rift-Related Magmatism of Active Continental Margins and Its Ore Potential (Nauka, Moscow, 1991) [in Russian].
V. V. Yarmolyuk and V. I. Kovalenko, “Geochemical and Isotopic Characteristics of the Anomalous Mantle of Northern Asia in the Late Paleozoic-Early Mesozoic: Data on Intraplate Mafic Magmatism,” Dokl. Akad. Nauk 375, 525–530 (2000) [Dokl. Earth Sci. 375A, 1427–1432 (2000)].
V. V. Yarmolyuk and V. I. Kovalenko, “Deep Geodynamics and Mantle Plumes: Their Role in the Formation of the Central Asian Fold Belt,” Petrologiya 11, 556–586 (2003) [Petrology 11, 504–533 (2003)].
V. V. Yarmolyuk, M. V. Durante, V. I. Kovalenko, et al., “Age of the Comendite-Alkali Granite Association of Southern Mongolia,” Izv. Akad. Nauk SSSR, Ser. Geol., No. 9, 40–48 (1981).
V. V. Yarmolyuk, V. S. Samoilov, V. G. Ivanov, et al., “Composition and Sources of Basalts in the Late Paleozoic Rift System of Central Asia: Geochemical and Isotopic Data,” Geokhimiya, No. 10, 1027–1042 (1999) [Geochem. Int. 37, 921–935 (1999)].
V. V. Yarmolyuk, V. I. Kovalenko, and M. I. Kuz’min, “North Asian Superplume Activity in the Phanerozoic: Magmatism and Geodynamics,” Geotektonika, No. 5, 3–29 (2000) [Geotectonics 34, 343–366 (2000)].
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Original Russian Text © A.M. Kozlovsky, V.V. Yarmolyuk, V.M. Savatenkov, V.P. Kovach, 2006, published in Petrologiya, 2006, Vol. 14, No. 4, pp. 358–383.
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Kozlovsky, A.M., Yarmolyuk, V.V., Savatenkov, V.M. et al. Sources of basaltoid magmas in rift settings of an active continental margin: Example from the bimodal association of the Noen and Tost ranges of the Late Paleozoic Gobi-Tien Shan rift zone, southern Mongolia. Petrology 14, 337–360 (2006). https://doi.org/10.1134/S0869591106040023
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DOI: https://doi.org/10.1134/S0869591106040023