The Lycian ophiolite in SW Turkey is mainly exposed in the Marmaris-Köyceğiz (Muğla) and Yeşilova (Burdur) regions. Its mantle section is widely exposed around Marmaris (=Marmaris peridotite) and is primarily composed of harzburgite of abyssal affinity with sparse lenses of dunites. Unusual chromitites indicating complicated mantle processes for chromitite genesis in the Marmaris peridotite have been discovered. The Marmaris harzburgite is characterised by moderate Cr# (=Cr/(Cr + Al); ~0.5) spinels and very low Na2O contents (<0.1 wt%) in clinopyroxene. Extremely high-Al chromitites, whose spinel show very low Cr# (<0.07), were found as pods in some dunites. Their spinels are far lower in Cr# than the lowest Cr# of the spinels in podiform chromitites (0.177) reported thus far. High-Cr chromitite pods, which are similar in chemistry (Cr# of spinel; ~ 0.7) to the most common podiform chromitite, were also found in the same peridotite. Dunite envelopes are thinner around the high-Al chromitite than around the high-Cr chromitite, but they are similar to each other in spinel Cr# (mainly ~ 0.5). The parental melt, from which the high-Al spinels of chromitites crystallised, contains relatively high Al2O3 (22–23 wt%) and low TiO2 content (<0.2 wt%) compared to mid-ocean ridge basalts. On the other hand, relatively low Al2O3 (12–13 wt%) and higher TiO2 (0.2–0.5. wt%) concentrations were observed for the parental melt from which the high-Cr chromitites were crystallised, suggesting a boninitic affinity. The extremely high-Al chromitites possibly formed through faint interactions between intruding high-Al magma and harzburgite country rock. Such interactions are also responsible for the formation of a thin dunite envelope. The high-Cr chromitites did not form via in situ magma–peridotite interactions because of their far higher Cr# spinel (~0.7) than the spinel in dunites (~0.5). Instead, the high-Cr magma responsible for chromitite precipitation intruded and replaced an in situ-interacted magma in the dunite-lined channel within harzburgite. The Marmaris peridotite represents a slice of mantle wedge that evolved from an abyssal mantle.
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