Geodynamics of the inner and outer Zagros Ophiolite belt (Iran), inferred from the chemical composition of Cr-spinel in chromitites

摘要

The composition of chromian spinel in chromitites and their host peridotites from the Neyriz and Nain ophiolites in the Zagros ophiolite belt shows that there are remarkable compositional variations between these two ophiolites.The Nain ophiolite in the NW is dominated by harzburgite with limited and small-size chromitite pods, whereas the Neyriz ophiolite to the SW contains both harzburgite and dunite with a large potential for high-Cr chromitites.The Neyriz chromitites in the southern sectors (outer Zagros) are the product of typical fore-arc-related boninitic melts, whereas the Nain chromitites of the inner Zagros probably originated in a back-arc basin from island arc tholeiite and MORB-like magmas.