Intra-oceanic arcs of the Paleo-Asian Ocean

Inna Safonova, Alexey Kotlyarov, Sergey Krivonogov, Wenjiao Xiao

Research output: Contribution to journalReview articlepeer-review

70 Citations (Scopus)

Abstract

The paper reviews and integrates geological, geochronological, geochemical and isotope data from 21 intra-oceanic arcs (IOA) of the Paleo-Asian Ocean (PAO), which have been identified in the Central Asian Orogenic belt, the world largest accretionary orogeny. The data We discuss structural position of intra-oceanic arc volcanic rocks in association with back-arc terranes and accretionary complexes, major periods of intra-oceanic arc magmatism and related juvenile crustal growth, lithologies of island-arc terranes, geochemical features and typical ranges of Nd isotope values of volcanic rocks. Four groups of IOAs have been recognized: Neoproterozoic – early Cambrian, early Paleozoic, Middle Paleozoic and late Paleozoic. The Neoproterozoic – early Cambrian or Siberian Group includes eleven intra-oceanic arcs of eastern and western Tuva-Sayan (southern Siberia, Russia), northern and southwestern Mongolia and Russian Altai. The Early Paleozoic or Kazakhstan Group includes Selety-Urumbai, Bozshakol-Chingiz and Baydaulet-Aqastau arc terranes of the Kazakh Orocline. The Middle Paleozoic or Southern Group includes six arc terranes in the Tienshan orogen, Chinese Altai, East-Kazakhstan-West Junggar and southern Mongoia. Only one Late Paleozoic intra-oceanic arc has been reliably identified in the CAOB: Bogda in the Chinese Tienshan, probably due to PAO shrinking and termination. The lithologies of the modern and fossil arcs are similar, although the fossil arcs contain more calc-alkaline varieties suggesting either their more evolved character or different conditions of magma generation. Of special importance is identification of back-arc basins in old accretionary orogens, because boninites may be absent in both modern and fossil IOAs. The three typical scenarios of back-arc formation - active margin rifting, intra-oceanic arc rifting and fore-arc rifting were reconstructed in fossil intra-oceanic arcs. Some arcs might be tectonically eroded and/or directly subducted into the deep mantle. Therefore, the structural and compositional records of fossil intra-oceanic arcs in intracontinental orogens allow us to make only minimal estimations of their geometric length, life span, and crust thickness.

Original languageEnglish
Pages (from-to)167-194
Number of pages28
JournalGondwana Research
Volume50
DOIs
Publication statusPublished - 1 Oct 2017

Keywords

  • Back-arc basin
  • Central Asian Orogenic Belt
  • Geochemistry
  • Tectonic erosion
  • Western Pacific
  • ISLAND-ARC
  • ZIRCON U-PB
  • INNER-MONGOLIA
  • TUVA-MONGOLIA MASSIF
  • BONINITE SERIES VOLCANICS
  • GORNY-ALTAI
  • CONTINENTAL-CRUST FORMATION
  • TES-CHEM OPHIOLITE
  • OROGENIC BELT
  • TECTONIC EVOLUTION

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