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Ophiolitic rocks (chromitites and serpentinized peridotites) were petrologically examined in detail for the first time from Rayat, in the Iraqi part of the Zagros thrust zone, an ophiolitic belt. Almost all the primary silicates have been altered out, but chromian spinel has survived from alteration and gives information about the primary petrological characteristics. The protolith of the serpentinite was clinopyroxene-free harzburgite with chromian spinel of intermediate Cr# (= Cr/[Cr + Al] atomic ratio) of 0.5 to 0.6. The harzburgite with that signature is the most common in the mantle section of the Tethyan ophiolites such as the Oman ophiolite, and is the most suitable host for chromitite genesis. Except for one sample, which has Cr# = 0.6 for spinel, the Cr# of spinel is high, around 0.7, in chromitite. The variation in Cr# of spinel in chromitite observed here has been also reported in the Oman ophiolite. The peridotite with chromitite pods exposed at Rayat was derived from an ophiolite similar in petrological character to the Oman ophiolite, one of the typical Tethyan ophiolites (fragments of Tethyan oceanic lithosphere). This result is consistent with the previous interpretation based on geological analysis. [ABSTRACT FROM AUTHOR]

A recent geological field work in the Northeastern part of Iraqi Kurdistan and subsequent analytical studies showed that the previously reported metamorphosed limestone outcrops around Rayat area represent actually listvenite bodies. Field mapping and remote sensing applications were used to understand the spatial distribution of the listvenite; additionally petrographical, mineralogical and geochemical studies were applied in order to define the features of the listvenite and to provide an initial genetic model, as well as to assess potential mineralizations related to the listvenitization. Listvenitization occurred as a product of hydrothermal alteration of the Cr-rich serpentinised peridotite that extensively occurs in the area, and resulted in the formation of silica and carbonate listvenites, as well as transitional phases, with fuchsite mineralization being predominant along the sheared zones. The results of this study upgrade the broad area of Rayat as potential hydrothermal ore-forming system and provide a basis for future detail prospecting of the area. • Advanced listvenitization produced by hydrothermal alteration of ultramafic rocks in Rayat ophiolite area of Iraqi Kurdistan. • Fuchsite-mineralization is dominant throughout the shear zones. • The identification of the listvenite, upgrades the broader Rayat area regarding potential epithermal mineralizations. [ABSTRACT FROM AUTHOR]