Mesozoic back-arc extension in the active margin of the Iranian continental block: Constraints from age and geochemistry of the mafic lavas

Moghadam H., Rahgoshay M., Whitechurch H.

Ofioliti, vol.33, no.2, pp.95-103, 2008 (SCI-Expanded, Scopus) identifier identifier

  • Publication Type: Article / Article
  • Volume: 33 Issue: 2
  • Publication Date: 2008
  • Journal Name: Ofioliti
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.95-103
  • Keywords: Back-arc extension, Calc-alkaline trend, Iran, Island-arc tholeiitic trend, K-ar age, Nain-baft, Ophiolites
  • Karadeniz Technical University Affiliated: No

Abstract

The Nain-Baft ophiolitic suture, along the active margin of the Central Iranian continental block (the Sanandaj-Sirjan zone) features back-arc extension during the Late Mesozoic. This ophiolitic belt is characterized by occurrence of mafic lavas including pillow lavas, diabasic dikes and layers, massive basaltic lavas and basaltic-andesitic rock fragments in the volcanic breccias. These mafic lavas display both calc-alkaline and island-arc tholeiitic affinities with enrichment in LILE and depletion in HFSE. Conventional K-Ar measurements on amphibole indicate the Middle Cretaceous for the creation and evolution of the Nain-Baft back-arc basins. As a result of oblique subduction of the Tethyan Ocean, a narrow transtensional back-arc basin could start to open along large transcurrent faults in the active margin of the Iranian continental block.