Mineralogy and composition of the chromitites and their platinum-group minerals from Ortaca (Mugla-SW Turkey): evidence for ophiolitic chromitite genesis


Uysal I. , Sadiklar M. , Tarkian M., Karsli O., Aydin F.

MINERALOGY AND PETROLOGY, cilt.83, ss.219-242, 2005 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 83
  • Basım Tarihi: 2005
  • Doi Numarası: 10.1007/s00710-004-0063-3
  • Dergi Adı: MINERALOGY AND PETROLOGY
  • Sayfa Sayıları: ss.219-242

Özet

A large number of podiform chromitite bodies of massive, disseminated and nodular type have been located in ultramafic units, composed of depleted mantle harzburgite and dunite of the Marmaris Peridotite from Ortaca (Mugla, SW Turkey). The chromite ore bodies are surrounded by dunite envelopes of variable thickness, exhibiting transitional boundaries to harzburgite host rocks. Chromitites, containing a large number of inclusions, i.e. silicates, base metal sulphides and alloys, and platinum-group minerals (PGM) ;have a wide range of chemical composition. The Cr# [Cr/( Cr+Al)] values of most chromitites are high (0.61 - 0.81) and Mg# [Mg/(Mg+Fe2+)] values range between 0.65 and 0.71 with TiO2 content lower than 0.24wt.%, which may reflect the crystallization of chromites from boninitic magmas in supra-subduction setting environment. Platinum-group minerals ( PGM) such as laurite, erlichmanite and Os - Ir alloys, silicates such as olivine, clinopyroxene and amphibole, and base metal sulphides (BM-S), alloys (BM-A) and arsenides (BM-As) are found as inclusions in chromite or in the serpentine matrix.