Did Paleo-Tethyan anoxia kill arc magma fertility for porphyry copper formation?

Richards J. P. , Şengör A. M. C.

GEOLOGY, vol.45, no.7, pp.591-594, 2017 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 45 Issue: 7
  • Publication Date: 2017
  • Doi Number: 10.1130/g38954.1
  • Journal Name: GEOLOGY
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.591-594
  • Istanbul Technical University Affiliated: Yes


The Tethyan orogen is host to numerous porphyry Cu +/- Mo +/- Au deposits, but the majority formed during subduction of the Neo-Tethyan ocean basin in the late Mesozoic-Cenozoic; very few deposits have been found associated with Paleo-Tethyan subduction. We propose that this sparsity is due to widespread anoxia in the Paleo-Tethyan ocean basin, leading to the generation of relatively reduced arc magmas that were infertile for porphyry Cu formation. A compilation of published geochemical data indicates that Neo-Tethyan arc rocks have higher average Cu contents and V/Sc and Sr/Y ratios compared to Paleo-Tethyan rocks, indicating higher magmatic oxidation states and greater fertility for ore formation during Neo-Tethyan subduction. Subduction of relatively reduced oceanic lithosphere, or reduction of normal moderately oxidized arc magmas by interaction with reduced lithosphere, can therefore destroy the ore-forming potential of arc magmatic suites.