Contributions to Mineralogy and Petrology

, Volume 165, Issue 4, pp 641–662

Origin of the Tongbai-Dabie-Sulu Neoproterozoic low-δ18O igneous province, east-central China

  • Bin Fu
  • Noriko T. Kita
  • Simon A. Wilde
  • Xiaochun Liu
  • John Cliff
  • Alan Greig
Original Paper

DOI: 10.1007/s00410-012-0828-3

Cite this article as:
Fu, B., Kita, N.T., Wilde, S.A. et al. Contrib Mineral Petrol (2013) 165: 641. doi:10.1007/s00410-012-0828-3

Abstract

Zircons from 71 diverse rocks from the Qinling-Tongbai-Dabie-Sulu orogenic belt in east-central China and, for comparison, eight from adjoining areas in the South China and North China blocks, have been analyzed for in situ 18O/16O ratio and/or U–Pb age to further constrain the spatial distribution and genesis of Neoproterozoic low-δ18O magmas, that is, δ18O(zircon) ≤4 ‰ VSMOW. In many metaigneous rock samples from Tongbai-Dabie-Sulu, including high-pressure and ultrahigh-pressure eclogites and associated granitic orthogneisses, average δ18O values for Neoproterozoic “igneous” zircon cores (i.e., 800–600 Ma) vary from −0.9 to 6.9 ‰, and from −9.9 to 6.8 ‰ for Triassic metamorphic rims (i.e., 245–200 Ma). The former extend to values lower than zircons in primitive magmas from the Earth’s mantle (ca. 5–6 ‰). The average Δ18O (metamorphic zircon − “igneous” zircon) values vary from −11.6 to 0.9 ‰. The large volume of Neoproterozoic low-δ18O igneous protoliths at Tongbai-Dabie-Sulu is matched only by the felsic volcanic rocks of the Snake River Plain hotspot track, which terminates at the Yellowstone Plateau. Hence, the low-δ18O values at Tongbai-Dabie-Sulu are proposed to result from shallow subcaldera processes by comparison with Yellowstone, where repeated caldera-forming magmatism and hydrothermal alteration created similar low-δ18O magmas. However, the possibility of involvement of meltwaters from local continental glaciations, rather than global Neoproterozoic glaciations, cannot be precluded. Our data indicate that Neoproterozoic low-δ18O magmas that are either subduction- or rift-related are present locally along the western margin of the South China Block (e.g., Baoxing Complex). It appears that Neoproterozoic 18O-depletion events in the South China Block as the result of hydrothermal alteration and magmatism affected a much larger area than was previously recognized.

Keywords

ZirconOxygen isotopesUltrahigh-pressure metamorphismQinling-Tongbai-Dabie-Sulu orogenic beltSouth China Block

Supplementary material

410_2012_828_MOESM1_ESM.xls (1.8 mb)
Supplementary material 1 (XLS 1807 kb)

Copyright information

© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • Bin Fu
    • 1
  • Noriko T. Kita
    • 2
  • Simon A. Wilde
    • 3
  • Xiaochun Liu
    • 4
  • John Cliff
    • 5
  • Alan Greig
    • 1
  1. 1.School of Earth SciencesThe University of MelbourneParkvilleAustralia
  2. 2.WiscSIMS, Department of GeoscienceUniversity of WisconsinMadisonUSA
  3. 3.Department of Applied GeologyCurtin UniversityPerthAustralia
  4. 4.Institute of GeomechanicsChinese Academy of Geological SciencesBeijingPeople’s Republic of China
  5. 5.Centre for Microscopy, Characterisation and AnalysisThe University of Western AustraliaCrawleyAustralia