Geochemistry and petrology of igneous assemblage in the south of Qorveh area, west Iran

The Qorveh area is located in west Iran and belongs to the Sanandaj–Sirjan plutono-metamorphic zone. The igneous assemblage of Qorveh was generated by subduction of the Neo-Tethys Ocean beneath the Iranian microplate during the Mesozoic and Cenozoic. The Qorveh igneous activity produced several sequences of plutonic (subvolcanic) and volcanic rocks, which host iron deposits in the Qorveh area. Plutonic rocks in this area are comprised of a subvolcanic complex of granite, quartz-monzonite, quartz-monzodiorite, monzonite, diorite, and minor gabbros with a volcanic sequences comprised of rhyolitic rocks. The coeval suite of rocks are metaluminous to slightly peraluminous (A/CNK = 0.64–1.16) and are calc-alkaline to alkaline. They also have moderate REE contents (∑REE = 72–292 ppm and La/Yb = 2.6–9 ppm for plutonic samples; ∑REE = 177–209 ppm and La/Yb = 4.2–9 ppm for volcanic samples) with negative (Eu/Eu* = 0.4–0.8 ppm) to positive Eu anomalies (Eu/Eu* = 1.1–1.3 ppm). The lithological, mineralogical, and geochemical studies together with field observations indicate that these rocks were generated by different magmatic processes. All these rocks have geochemical attributes of an active continental margin geodynamic environment (e.g. Cs, Th, K, Rb, and LREE enrichments; P, Nb, Ti, Y, and HREE depletions) and have I-type magmatic characteristics. Also granites, rhyolites, and rhyolitic–rhyodacitic tuffs possess some crustal A-type geochemical characteristics, indicative of local transpression in this dominantly convergent geodynamic environment.