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Mineralogical, Geochemical, and Nd-Sr Isotope Characteristics of Amphibolites from the Alag-Khadny High-Pressure Complex (SW Mongolia): Intracontinental Rifting as a Precursor of Continental-Margin Subduction

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Abstract

Within subduction-accretion complexes, high-pressure rocks (blueschists, eclogites) are commonly juxtaposed with lower-grade rocks, which represent their retrograded counterparts or were involved into accretionary event at later stages, and thus characterize distinct stages of evolution of accretionary belts. In SW Mongolia, the Central Asian Orogenic Belt includes Neoproterozoic–Early Paleozoic paleosubduction complexes represented by eclogites and associated rocks of the Alag-Khadny accretionary complex. This paper reports the results of mineralogical, geochemical and isotopic studies of amphibolites from this complex, the geochemical nature and relationships of which with eclogites have been yet uncertain. The texture of the studied rocks varies from fine- and medium-grained granoblastic and nematoblastic amphibole–plagioclase–epidote rocks to medium-grained nematoblastic amphibole–epidote–albite–titanite amphibolites, which experienced intense recrystallization as a response to late deformations. Primary assemblages include pargasite and Mg-hornblende ([B]Na = 0.07–0.16, IVAl = 0.79–1.69, [A](Na + K + 2Ca) = 0.14–0.64, [C](Al+ Ti + Fe3+) = 0.58–1.29, Fe2+/(Fe2+ + Mg) = 0.18–0.46 at Fe3+/(Fe3++Al) = 0.18–0.77), low-to-medium-Ca plagioclase (An24–36), and epidote–clinozoisite (0.08 < \({{X}_{{{\text{F}}{{{\text{e}}}^{{{\text{3 + }}}}}}}}\) < 0.16), whereas the retrograde assemblage is represented by albite and Mg-hornblende. Calculations using amphibole composition and amphibole/amphibole–plagioclase thermobarometry revealed peak P-T conditions up to 570–630°С and 7–9 kbar ascribed to the high-T epidote-amphibolite facies with subsequent greenschist-facies retrogression. The major-element composition of the amphibolites corresponds to low-alkali moderate-Ti tholeiites, although their trace-element composition varies significantly from N-MORB to E-MORB-type basalts, which are variably enriched in LREE, Nb, Ta, Th, U, and show negative Eu and Ti anomalies due to fractionation of parental melts for precursor rocks. Isotopic composition of Nd (εNd(550) from +5.1 to –9.1) and Sr ((87Sr/86Sr)550 = 0.7057–0.7097) indicates distinct mainly moderately-depleted nature of mantle sources for the mafic rocks, but also highlights the involvement of “anomalous” mantle domains with unradiogenic Nd composition. The data supports that the precursor rocks of the amphibolites were formed during intracontinental extension of a continental margin, which was likely linked to opening of a limited Neoproterozoic oceanic basin with a subsequent Late Vendian–Early Cambrian convergence. The medium- to high-pressure metamorphism of amphibolites had similar P-T conditions to that of retrograde metamorphism of eclogites and associated metasediments and was directly related to the Early Paleozoic subduction-accretion metamorphism (~550–540 Ma), or results from the final accretion during the formation of a tectonic mélange zone between the Lake zone and Dzabkhan terrane (~515–490 Ma or younger).

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  1. Supplementary materials to Russian and English on-line versions can be found at https://elibrary.ru/ and http://link.springer.com/, respectively: ESM_1. xlsx—Compositions of minerals of epidote–clinozoisite amphibolites from the Alag-Khadny Complex, SW Mongolia.

REFERENCES

  1. Andreasson, P.-G. and Albrecht, L., Derivation of 500 Ma eclogites from the passive margin of Baltica and a note on the tectonometamorphic heterogeneity of eclogite-bearing crust, Geol. Mag., 1995, vol. 132, no. 6, pp. 729–738.

    Article  Google Scholar 

  2. Bold, U., Crowley, J.L., Smith, E.F., et al., Neoproterozoic to Early Paleozoic tectonic evolution of the Zavkhan terrane of Mongolia: implications for continental growth in the Central Asian Orogenic Belt, Lithosphere, 2016, vol. 8, no. 6, pp. 729–750.

    Article  Google Scholar 

  3. Brown, E.H., The crossite content of Ca-amphibole as a guide to pressure of metamorphism, J. Petrol., 1977, vol. 18, pp. 53–72.

    Article  Google Scholar 

  4. Buriánek, D., Schulmann, K., Hrdličkova, K., et al., Geochemical and geochronological constraints on distinct Early Neoproterozoic and Cambrian accretionary events along southern margin of the Baydrag continent in Western Mongolia, Gondwana Res., 2017, vol. 47, pp. 200–227.

    Article  Google Scholar 

  5. Castillo, P.R., Hawkins, J.W., Lonsdale, P.F., et al., Petrology of Alarcon rise lavas, Gulf of California: nascent intracontinental ocean crust, J. Geophys. Res., 2002, vol. 107, p. 2222.

    Google Scholar 

  6. Dilek, Y. and Furnes, H., Ophiolites and their origins, Elements, 2014, vol. 10, pp. 93–100.

    Article  Google Scholar 

  7. Dobretsov, N.L., Buslov, M.M., and Vernikovsky, V.A., Neoproterozoic to Early Ordovician evolution of the paleo-Asian ocean: implications to the break-up of Rodinia, Gondwana Res., 2003, vol. 6, no. 2, pp. 143–159.

    Article  Google Scholar 

  8. Ernst, W.G. and Liu, J.G., Experimental phase–equilibrium study of Al- and Ti-contents of calcic amphibote in MORB - a semiquantitative thermobarometer, Am. Mineral., 1998, vol. 83, pp. 952–969.

    Article  Google Scholar 

  9. Ernst, W.G., Alpine and Pacific styles of Phanerozoic mountain building: subduction-zone petrogenesis of continental crust, Terra Nova, 2005, vol. 17, pp. 165–188.

    Article  Google Scholar 

  10. Frost, B.R., Chamberlain, K.R., and Schumacher, J.C., Sphene (titanite): phase relations and role as a geochronometer, Chem. Geol., 2000, vol. 172, pp. 131–148.

    Article  Google Scholar 

  11. Gale, A., Dalton, C.A., Langmuir, C.H., et al., The mean composition of ocean ridge basalts, Geochem. Geophys. Geosyst., 2013, vol. 14, pp. 489–518.

    Article  Google Scholar 

  12. Gerya T.V., Perchuk L.L., Tribule K., et al., Petrology of the Tumanshet zonal metamorphic complex, Eastern Sayan, Petrology, 1997, vol. 5, no. 6, pp. 503–533.

    Google Scholar 

  13. Gornova, M.A., Karimov, A.A., Skuzovatov, S.Yu., and Belyaev, V.A., From decompression melting to mantle-wedge refertilization and metamorphism: insights from peridotites of the Alag-Khadny accretionary complex (SW Mongolia), Minerals, 2020, vol. 10, no. 5, p. 396.

    Article  Google Scholar 

  14. Guintoli, F., Menegon, L., and Warren, C.J., Replacement reactions and deformation by dissolution and precipitation processes in amphibolites, J. Metamorph. Geol., 2018, vol. 36, pp. 1263–1286.

    Article  Google Scholar 

  15. Hanžl, P. and Aichler, J., Geological survey of the Mongolian Altay at a scale 1 : 50 000 (Zamtyn Nuruu—50). Final report, Czech Geological Survey, Prague: Czech Republic, 2007.

  16. Hawthorne, F.C., Oberti, R., Harlow, G.E., et al., Nomenclature of the amphibole supergroup, Am. Mineral., 2012, vol. 97, pp. 2031–2048.

    Article  Google Scholar 

  17. Holland, VOL. and Blundy, J., Non-ideal interactions in calcic amphiboles and their bearing on amphibole-plagioclase thermometry, Contrib. Mineral. Petrol., 1994, vol. 116, pp. 433–447.

    Article  Google Scholar 

  18. Jahn, B.-M., Wu, F., and Chen, B., Granitoids of the Central Asian Orogenic Belt and continental growth in the Phanerozoic, Trans. R. Soc. Edinburgh: Earth Sci., 2000, vol. 91, pp. 181–193.

    Google Scholar 

  19. Javkhlan, O., Takasu, A., Fazle, KabirMd., and Batulzii, D., Multiple metamorphic events recorded within eclogites of the Chandman District, SW Mongolia, Minerals, 2019, vol. 9, p. 495.

    Article  Google Scholar 

  20. Kapp, P., Manning, C.E., and Tropper, P., Phase-equilibrium constraints on titanite and rutile activities in mafic epidote amphibolites and geobarometry using titanite–rutile equilibria, J. Metamorph. Geol., 2009, vol. 27, pp. 509–521.

    Article  Google Scholar 

  21. Keskinen, M. and Liou, J.G., Stability relations of Mn–Fe–Al piemontite, J. Metamorph. Geol., 1987, vol. 5, pp. 495–507.

    Article  Google Scholar 

  22. Khain, E.V., Bibikova, E.V., Salnikova, E.E., et al., The paleo-Asian ocean in the Proterozoic and Early Paleozoic: new geochronologic data and paleotectonic reconstructions, Precambrian Res., 2003, vol. 122, pp. 329–358.

    Article  Google Scholar 

  23. Kirchner, T.M. and Gillis, K.M., Mineralogical and strontium isotopic record of hydrothermal processes in the lower ocean crust at and near the east pacific rise, Contrib. Mineral. Petrol., 2012, vol. 164, pp. 123–141.

    Article  Google Scholar 

  24. Kozakov, I.K., Kovach, V.P., Salnikova, E.B., et al., Formation of the Neoproterozoic continental crust in the structures of the central segment of the Central Asian Fold Belt, Petrology, 2021, vol. 29, no. 2, pp. 195–220.

    Article  Google Scholar 

  25. Kozakov, I.K., Salnikova, E.B., Wang, T., et al., Early Precambrian crystalline complexes of the Central Asian microcontinent: age, sources, tectonic position, Stratigraphy. Geol. Correlation, 2007, vol. 15, no. 2, pp. 121–140.

    Article  Google Scholar 

  26. Kozakov, I.K., Yarmolyuk, V.V., Kovach, V.P., et al., The Early Baikalian crystalline complex in the basement of the Dzabkhan microcontinent of the Early Caledonian orogenic area, Central Asia, Stratigraphy. Geol. Correlation, 2012, vol. 20, no. 3, pp. 3-12.

    Google Scholar 

  27. Kröner, A., Lehmann, J., Schulmann, K., et al., Lithostratigraphic and geochronological constraints on the evolution of the Central Asian Orogenic Belt in SW Mongolia: Early Paleozoic rifting followed by Late Paleozoic accretion, Am. J. Sci., 2010, vol. 310, pp. 523–574.

    Article  Google Scholar 

  28. Laird, J. and Albee, A.L., Pressure, temperature, and time indicators in mafic schist: their application to reconstructing the polymetamorphic history of Mermont, Am. J. Sci., 1981, vol. 281, pp. 127–175.

    Article  Google Scholar 

  29. Locock, A.J., An excel spreadsheet to classify chemical analyses of amphiboles following the IMA 2012 recommendations, Comp. Geosci., 2014, vol. 62, pp. 1–11.

    Article  Google Scholar 

  30. Maruyama, S., Suzuki, K., and Liou, J., Greenschist-amphibolite transition equilibria at low pressures, J. Petrol., 1983, vol. 24, pp. 583–604.

    Article  Google Scholar 

  31. Matsumoto, I. and Tomurtogoo, O., Petrological characteristics of the Pantaishir ophiolite complex, Altai region, Mongolia: coexistence of podiform chromitite and boninite, Gondwana Res., 2003, vol. 6, pp. 161–169.

    Article  Google Scholar 

  32. Montanini, A., Tribuzio, R., and Vernia, L., Petrogenesis of basalts and gabbros from an ancient continent–ocean transition (external Liguride ophiolites, northern Italy), Lithos, 2008, vol. 101, pp. 453–479.

    Article  Google Scholar 

  33. Niu, Y., Mantle melting and melt extraction processes beneath ocean ridges: evidence from abyssal peridotites, J. Petrol., 1997, vol. 38, no. 8, pp. 1047–1074.

    Article  Google Scholar 

  34. Oh, C.W. and Liou, J.G., A petrogenetic grid for eclogite and related facies under high-pressure metamorphism, The Island Arc, 1998, vol. 7, pp. 36–51.

    Article  Google Scholar 

  35. Pearce, J.A., Immobile element fingerprinting of ophiolites, Elements, 2014, vol. 10, pp. 101–108.

    Article  Google Scholar 

  36. Pearce, J.A., Ernst, R.E., Peate, D.W., and Rogers, C., LIP printing: use of immobile element proxies to characterize large igneous provinces in the geologic record, Lithos, 2021, p. 1016. https://doi.org/10.1016/j.lithos.2021.106068

  37. Raase, P., Al and Ti contents of hornblende, indicators of pressure and temperature of regional metamorphism, Contrib. Mineral. Petrol., 1974, vol. 45, pp. 231–236.

    Article  Google Scholar 

  38. Raith, M., The A1–Fe(III) epidote miscibility gap in a metamorphic profile through the Penninic series of the Tauern window, Austria, Contrib. Mineral. Petrol., 1976, vol. 57, pp. 99–117.

    Article  Google Scholar 

  39. Rudnev, S.N., Kovach, V.P., and Ponomarchuk, V.A., Vendian–Early Cambrian island-arc plagiogranitoid magmatism in the Altai–Sayan folded area and in the Lake Zone of Western Mongolia (geochronological, geochemical and isotope data), Russ. Geol. Geophys., 2013, vol. 54, no. 10, pp. 1272–1287.

    Article  Google Scholar 

  40. Saccani, E., Allahyari, K., and Rahimzadeh, B., Petrology and geochemistry of mafic magmatic rocks from the Sarve-Abad ophiolites (Kurdistan region, Iran): evidence for interaction between MORB-type asthenosphere and OIB-type components in the southern Neo-Tethys Ocean, Tectonophysics, 2014, vol. 621, pp. 132–147.

    Article  Google Scholar 

  41. Saccani, E., Dilek, Y., Marroni, M., and Pandolfi, L., Continental margin ophiolites of Neotethys: remnants of ancient ocean-continent transition zone (OCTZ) lithosphere and their geochemistry, mantle sources and melt evolution patterns, Episodes, 2015, vol. 38, pp. 230–249.

    Article  Google Scholar 

  42. Saccani, E., A new method of discriminating different types of post-Archean ophiolitic basalts and their tectonic significance using Th–Nb and Ce–Dy–Yb systematics, Geosc. Front., 2015, vol. 6, pp. 481–501.

    Article  Google Scholar 

  43. Schumacher, J.C., Metamorphic amphiboles: composition and coexistence, Rev. Mineral. Geochem., 2007, vol. 67, pp. 359–416.

    Article  Google Scholar 

  44. Sengör, A.M.C., Natal’in, B.A., and Burtman, V.S., Evolution of the Altaid tectonic collage and Paleozoic crustal growth in Eurasia, Nature, 1993, vol. 364, pp. 299–307.

    Article  Google Scholar 

  45. Skuzovatov, S.Yu., Nature and (in-)coherent metamorphic evolution of subducted continental crust in the Neoproterozoic accretionary collage of SW Mongolia, Geosci. Front., 2021, vol. 12, no. 3, p. 101097.

    Article  Google Scholar 

  46. Skuzovatov, S.Yu., Shatsky, V.S., Dril, S.I., and Perepelov, A.B., Elemental and isotopic (Nd–Sr–O) geochemistry of eclogites from the Zamtyn-Nuruu area (SW Mongolia): crustal contribution and relation to Neoproterozoic subduction–accretion events, J. Asian Earth Sci., 2018, vol. 167, pp. 33–51.

    Article  Google Scholar 

  47. Song, S., Zhang, L., Niu, Y., Su, L., et al., Evolution from oceanic subduction to continental collision: a case study from the northern Tiberan plateau based on geochemical and geochronological data, J. Petrol., 2006, vol. 47, no. 3, pp. 435–455.

    Article  Google Scholar 

  48. Spear, F.S., NaSi-CaAl exchange equilibrium between plagioclase and amphibole: an empirical model, Contrib. Mineral. Petrol., 1980, vol. 80, pp. 140–149.

    Google Scholar 

  49. Starr, P.G. and Pattison, D.R.M., Equilibrium and disequilibrium processes across the greenschist—amphibolite transition zone in metabasites, Contrib. Mineral. Petrol., 2019, vol. 174, no. 2, pp. 1–18.

    Article  Google Scholar 

  50. Starr, P.G., Pattison, D.R.M., and Ames, D.E., Mineral assemblages and phase equilibria of metabasites from the prehnite–pumpellyite to amphibolite facies, with the Flin Flon greenstone belt (Manitoba) as a type example, J. Metamorph. Geol., 2020, vol. 38, pp. 71–102.

    Article  Google Scholar 

  51. Štípská, P., Schulmann, K., Lehmann, J., et al., Early Cambrian eclogites in SW Mongolia: evidence that the palaeo-Asian ocean suture extends further than expected, J. Metamorph. Geol., 2010, vol. 28, pp. 915–933.

    Article  Google Scholar 

  52. Sun, S.-S. and McDonough, W.F., Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes, Magmatism in the Ocean Basins, Saunders, A.D. and Norry, M.J., Eds., Geol. Soc. Spec. Publ., 1989, vol. 42, pp. 313–345.

    Google Scholar 

  53. Tomurtogoo, O., A new tectonic scheme of the Paleozoides in Mongolia, Mongol. Geosci., 1997, vol. 3, pp. 12–17.

    Google Scholar 

  54. Triboulet, C. and Audren, C., Controls on P-T-t deformation path from amphibole zonation during progressive metamorphism of basic rocks (estuary of the River Vilaine, South Brittany, France), J. Metamorph. Geol., 1988, vol. 6, pp. 117–133.

    Article  Google Scholar 

  55. White, W.M. and Klein, E.M., Composition of the oceanic crust, Treatise on Geochemistry, 2nd Ed., 2014, vol. 4, pp. 457–496.

    Book  Google Scholar 

  56. Whitney, D.L. and Evans, B.W., Abbreviations for names of rock-forming minerals, Am. Mineral., 2010, vol. 95, pp. 185–187.

    Article  Google Scholar 

  57. Yarmolyuk V.V., Kovalenko V.I., Kovach V.P., et al., Early stages of the Paleoasian ocean formation: results of geochronological, isotopic, and geochemical investigations of Late Riphean and Vendian–Cambrian complexes in the Central Asian Foldbelt, Dokl. Earth Sci., vol. 410, no. 5, pp. 1184–1189.

  58. Zenk, M. and Schulz, B., Zoned Ca-amphiboles and related P-T evolution in metabasites from the classical Barrovian metamorphic zones in Scotland, Mineral. Mag., 2004, vol. 68, no. 5, pp. 769–786.

    Article  Google Scholar 

  59. Zhang, G., Zhang, L., and Christy, A.G., From oceanic subduction to continental collision: an overview of HP–UHP metamorphic rocks in the North Qaidam UHP belt, NW China, J. Asian Earth Sci., 2013, vol. 63, pp. 98–111.

    Article  Google Scholar 

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ACKNOWLEDGMENTS

We are grateful to P.Ya. Azimov and I.K. Kozakov for valuable comments and suggestions, which allowed us to improve interpretation and presentation of materials.

Funding

The studies were performed in the framework of the government-financed task of the Vinogradov Institute of Geochemistry, Siberian Branch, Russian Academy of Sciences (project nos. 0284-2021-0007 and 0284-2021-0006) and were supported by the Russian President Foundation (project MK-67.2020.5).

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  1. Vinogradov Institute of Geochemistry, Russian Academy of Sciences, Siberian Branch, Irkutsk, Russia

    S. Yu. Skuzovatov, M. A. Gornova & A. A. Karimov

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Skuzovatov, S.Y., Gornova, M.A. & Karimov, A.A. Mineralogical, Geochemical, and Nd-Sr Isotope Characteristics of Amphibolites from the Alag-Khadny High-Pressure Complex (SW Mongolia): Intracontinental Rifting as a Precursor of Continental-Margin Subduction. Petrology 30, 523–544 (2022). https://doi.org/10.1134/S0869591122040051

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