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International Journal of Earth Sciences

, Volume 91, Issue 1, pp 3–19 | Cite as

Peraluminous granites frequently with mantle-like isotope compositions: the continental-type Murzinka and Dzhabyk batholiths of the eastern Urals

  • A. GerdesEmail author
  • P. Montero
  • F. Bea
  • G. Fershater
  • N. Borodina
  • T. Osipova
  • G. Shardakova
Original paper

Abstract

Murzinka and Dzhabyk are continental-type batholiths of the middle and southern East Uralian domain. They comprise mainly undeformed peraluminous K-rich granites whose elemental composition is similar to some late-Variscan granites of western Europe, but with much more primitive Sr and Nd isotope ratios. Murzinka (254±5 Ma) is composed of silica-rich granites forming two different rock series with a 87Sr/86Srinit of 0.709 and 0.704, respectively. Both series have enormous variations in εNd255 (–11.9 to –0.1 and –8.9 to +4.1) that reveal derivation from heterogeneous sources. Dzhabyk (291±4 Ma) also comprises two coeval magmas which yielded voluminous granites and quartz-monzonites, respectively, with smaller differences in 87Sr/86Srinit and εNd290 (~0.7043, +0.8 to +1.6 and ~0.7049, 0.0 to +0.8). Despite their isotope compositions both batholiths lack evidence of genetic involvement of a mantle-derived parental magma. Moreover, we suggest that Dzhabyk granitoids were generated by polybaric partial melting of Paleozoic island-arc material, whereas Murzinka granitoids derived from an extremely heterogeneous source consisting mainly of Paleozoic and Proterozoic metagreywackes. This implies a relative fast reworking of juvenile arc crust and burial of the protoliths during the orogenic evolution of the Urals. Since there is neither evidence of significant extension, nor a direct link with subduction, we suggest that the main cause for late-orogenic anatexis was elevated heat production and fertility in the protolith, perhaps combined with some additional heat from unexposed mafic intrusions.

Granite genesis Post-collisional Ural mountains Variscan granites Sr–Nd isotope systematic Source heterogeneity Crustal evolution 

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Copyright information

© Springer-Verlag 2001

Authors and Affiliations

  • A. Gerdes
    • 1
    Email author
  • P. Montero
    • 1
  • F. Bea
    • 1
  • G. Fershater
    • 2
  • N. Borodina
    • 2
  • T. Osipova
    • 2
  • G. Shardakova
    • 2
  1. 1.Department of Mineralogy and Petrology, University of Granada, Campus Fuentenueva, 18002 Granada, SpainSpain
  2. 2.Institute of Geology and Geochemistry, Russian Academy of Sciences, Pochtovi per. 7, 620219 Ekaterinburg, RussiaRussia

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