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

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dc.contributor.authorAli, Sarmad A.
dc.contributor.authorIsmail, Sabah A.
dc.contributor.authorNutman, Allen P.
dc.contributor.authorBennett, Vickie C.
dc.contributor.authorJones, Brian G.
dc.contributor.authorBuckman, Solomon
dc.date.accessioned2016-08-16T01:10:29Z
dc.date.available2016-08-16T01:10:29Z
dc.date.issued2016
dc.description.abstractThe 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* < 1 for the Aulan sample with initial εHf of + 8.6 ± 0.2 is interpreted as the magma dominated by contributions from fluid fluxing of the mantle wedge and lesser contributions of low temperature melt from subducted slab sediment, in an oceanic setting. This mechanism can explain the sub-DM initial εHf value, without the need to invoke melting of significantly older (continental) crust in an Andean setting. We interpret the Kata–Rash igneous rocks as a fragment of the Late Cretaceous suprasubduction zone system (named here the Kata–Rash arc) that most likely developed within the Neotethys Ocean rather than at a continental margin. Subsequently during the latest Cretaceous to Paleocene, the arc was accreted to the northern margin of the Arabian plate. The results indicate a > 3000 km continuity of Cretaceous arc activity (Oman to Cyprus), that consumed Neotethyian oceanic crust between Eurasia and the Gondwanan fragment Arabia.en_AU
dc.description.sponsorshipLaboratory work was supported by the GeoQuEST Research Centre, University of Wollongong (UOW).en_AU
dc.identifier.issn0024-4937en_AU
dc.identifier.urihttp://hdl.handle.net/1885/107194
dc.publisherElsevieren_AU
dc.rights© 2016 Elsevieren_AU
dc.sourceLithosen_AU
dc.subjectIraqen_AU
dc.subjectNeotethysen_AU
dc.subjectZagrosen_AU
dc.subjectKata–Rashen_AU
dc.subjectShalir valleyen_AU
dc.subjectOphioliteen_AU
dc.titleThe intra-oceanic Cretaceous (~108Ma) Kata–Rash arc fragment in the Kurdistan segment of Iraqi Zagros suture zone: Implications for Neotethys evolution and closureen_AU
dc.typeJournal articleen_AU
local.bibliographicCitation.lastpage163en_AU
local.bibliographicCitation.startpage154en_AU
local.contributor.affiliationBennett, V. C., Research School of Earth Sciences, The Australian National Universityen_AU
local.contributor.authoremailVickie.Bennett@anu.edu.auen_AU
local.contributor.authoruidu8904005en_AU
local.identifier.citationvolume260en_AU
local.identifier.doi10.1016/j.lithos.2016.05.027en_AU
local.identifier.uidSubmittedByu1005913en_AU
local.publisher.urlhttp://www.elsevier.com/en_AU
local.type.statusPublished Versionen_AU

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