Proterozoic blueschist-bearing mélange in the Anti-Atlas mountains, Morocco

Kevin P. Hefferan, Hassan Admou, Rabia Hilal, Jeffrey A. Karson, Ali Saquaque, Thierry Juteau, M. Marcel Bohn, Scott D. Samson, Jacques M. Kornprobst

Research output: Contribution to journalArticle

48 Scopus citations

Abstract

Blueschists from the Bou Azzer inlier provide compelling evidence for Late Proterozoic subduction in the Anti-Atlas Mountains of Morocco. High-pressure/low-temperature metabasites containing blue amphibole minerals crossite and magnesioriebeckite record pressures in excess of 5 kbar. Together with regional relationships, the geologic setting of the blueschists constrains the polarity of Pan African subduction in this region, which occurred from ∼ 750 to 600 Ma. Blueschist facies rocks crop out in a heterogeneous assemblage of variably deformed and metamorphosed tectonic slices of ophiolitic fragments enclosed in a schistose serpentinite matrix. The mélange belt containing the blueschist facies rocks is intruded by a number of diorite plutons, one of which has yielded a U/Pb radiometric age of 650 Ma. Together with Transaharan Belt to the southeast, the Anti-Atlas suture zone exposed within the Bou Azzer inlier contains among the oldest known blueschist-bearing, ophiolitic mélanges in the world.

Original languageEnglish (US)
Pages (from-to)179-194
Number of pages16
JournalPrecambrian Research
Volume118
Issue number3-4
DOIs
StatePublished - Nov 25 2002

Keywords

  • Anti-Atlas Mountains
  • Blueschist
  • Neoproterozoic
  • Ophiolites
  • Pan African orogeny

ASJC Scopus subject areas

  • Geology
  • Geochemistry and Petrology

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    Hefferan, K. P., Admou, H., Hilal, R., Karson, J. A., Saquaque, A., Juteau, T., Bohn, M. M., Samson, S. D., & Kornprobst, J. M. (2002). Proterozoic blueschist-bearing mélange in the Anti-Atlas mountains, Morocco. Precambrian Research, 118(3-4), 179-194. https://doi.org/10.1016/S0301-9268(02)00109-2