40Ar/39Ar hornblende and biotite geochronology of the Bulfat Igneous Complex, Zagros Suture Zone, NE Iraq: New insights on complexities of Paleogene arc magmatism during closure of the Neotethys Ocean
MetadataShow full item record
In NE Iraq, the eastern edge of the Arabian plate is overlain by arc rock allochthons whose genesis and tectonic emplacement were related to the consumption and closure of the Neotethys Ocean. This paper demonstrates the occurrence of unrelated Paleogene arc rocks in two adjacent allochthons. The Bulfat Igneous Complex at Wadi Rashid (NE Iraq) is an intrusion within the Upper Allochthon Albian–Cenomanian Gimo–Qandil sequence suprasubduction zone assemblage. A thrust separates this allochthon from the underlying Lower Allochthon of the Eocene-Oligocene Walash–Naopurdan volcanic-sedimentary arc rocks. The Bulfat Igneous Complex at Wadi Rashid consists of gabbro and granitic composite intrusions in which components mingle down to a small scale. Textural relationships in the Bulfat Igneous Complex rocks indicate emplacement at high crustal levels with rapid cooling, which is consistent with amphibole geobarometry indicating crystallisation pressures between ~ 250 and 300 Mpa. Ti-rich igneous pargasite and Ti-rich igneous Fe-biotite from gabbroic and granitic components yielded 40Ar/39Ar ages of 39.23 ± 0.21 and 38.87 ± 0.24 Ma respectively. These ages agree within analytical error and suggest coeval emplacement and rapid cooling of mafic and felsic magmas in the Eocene, in an event that was distinct and much younger than the host Albian–Cenomanian rocks. This igneous event was unrelated to formation of Cenozoic rocks in the underlying, tectonically separate, lower allochthon. The trace element signatures of the Wadi Rashi volcanic rocks show volcanic-arc characteristics for the granites and the gabbroic rocks resemble E type MORB. The presence of Eocene arc-related rocks in two allochthons suggests complexity in Paleogene subduction systems, with possibly two subduction zones operating at that time.
Showing items related by title, author, creator and subject.
Neoproterozoic palaeogeography in the North Atlantic Region: Inferences from the Akkajaure and Seve Nappes of the Scandinavian CaledonidesKirkland, Chris; Bingen, B.; Whitehouse, M.; Beyer, E.; Griffin, W. (2011)The Scandinavian Caledonides exposes increasingly far travelled nappes upwards (westwards). The Lower- to Middle Allochthon are widely regarded as indigenous to the pre-Caledonian margin of Baltica (Fennoscandia), while ...
Vestiges of Saxothuringian crust in the central Sudetes, Bohemian massif: Zircon evidence of a recycled subducted slab provenanceMazur, S.; Turniak, K.; Szczepanski, J.; McNaughton, Neal (2013)Four detrital zircon concentrates from the metasediments and metavolcanics of the Central Sudetes, Bohemian Massif, have been dated using SHRIMP II. The Wyszki paragneiss yielded Precambrian age spectra similar to those ...
Age and significance of voluminous mafic-ultramafic magmatic events in the Murchison Domain, Yilgarn CratonIvanic, T.; Wingate, M.; Kirkland, Chris; van Kranendonk, M.; Wyche, S. (2010)Mafic-ultramafic rocks in structurally dismembered layered intrusions comprise approximately 40% by volume of greenstones in the Murchison Domain of the Youanmi Terrane, Yilgarn Craton. Mafic- ultramafic rocks in the ...