Petrochemistry and geotectonic setting of the Shalair granite, NE Iraq

Abstract

The igneous history of the (U. Cretaceous-Miocene) Shalair granite of NE Iraq shows great similarity to the post Caledonian Cheviot granite of NE England. The Shalair granite comprises at least one igneous cycle (made up of two rock units) starting with basic ganodiorite and including a late porphyritic igneous unit. It is a high level pluton made up of a number of intrusive phase intruding a pile of andesite of a similar composition to the bulk of the plutonics. The whole represents a multicomponent ring dyke, whose top is near the present level of erosion. Geographically the Shalair granite forms one of a group of granitic intrusion all lying to the East of the Zagros suture. They provide a strong evidence of close links in space and time with the Shalair granite. At Shalair a whole spectrum of igneous rocks from calc-alkaline to alkaline affinities could have formed by subduction followed by a collisional stage. The subduction of the Arabian plate under the Iranian plate was active during U. Cretaceous-Paleocene producing calc-alkaline suites cropping at Sirstan, Aulan, Mishao and Laladar. Eventually the subduction process stopped by continental collision, most probably during the Late Eocene-U. Miocene forming a special kind of S-granite cropping out at Damamna.