The intra-oceanic Cretaceous (~108Ma) Kata–Rash arc fragment in the Kurdistan segment of Iraqi Zagros suture zone: Implications for Neotethys evolution and closure

The Kata–Rash arc fragment is an allochthonous thrust-bound body situated near Penjween, 100 km northeast of Sulymannia city, Kurdistan Region, within the Iraqi portion of the Zagros suture zone. It forms part of the suprasubduction zone ‘Upper Allochthon’ terranes (designated as the Gimo–Qandil Group), which is dominated by calc-alkaline andesite and basaltic–andesite, rhyodacite to rhyolite, crosscut by granitic, granodioritic, and dioritic dykes. Previously, rocks of the Kata–Rash arc fragment were interpreted as a part of the Eocene Walash volcanic group. However, SHRIMP zircon U–Pb dates on them of 108.1 ± 2.9 Ma (Harbar volcanic rocks) and 107.7 ± 1.9 Ma (Aulan intrusion) indicate an Albian–Cenomanian age, which is interpreted as the time of igneous crystallisation. The Aulan intrusion zircons have initial εHf values of + 8.6 ± 0.2. On a Nb/Yb–Th/Yb diagram, all Kata–Rash samples fall within the compositional field of arc-related rocks, i.e. above the mid-ocean-ridge basalt (MORB)—ocean island basalt (OIB) mantle array. Primitive-mantle-normalised trace-element patterns for the Kata–Rash samples show enrichment in the large ion lithophile elements and depletion in the high-field-strength elements supporting their subduction-related character. Low Ba/La coupled with low La/Yb and Hf/Hf* 3000 km continuity of Cretaceous arc activity (Oman to Cyprus), that consumed Neotethyian oceanic crust between Eurasia and the Gondwanan fragment Arabia.Laboratory work was supported by the GeoQuEST Research Centre, University of Wollongong (UOW)