Late Cretaceous volcanism in the northern Urumieh- Dokhtar Magmatic Arc, central Iran

Late Cretaceous volcanic rocks in the Halab-Avaj-Nobaran region of the northern Urumieh-Dokhtar Magmatic Arc in Iran are relicts of Mesozoic activity when subduction-related magmatism migrated inland. They include subalka-line (transitional) basalts, basaltic trachyandesites, and dacites, which formed in association with various pyroclastic and sedimentary rocks. Their trace element composition is characterized by enrichment in large ion lithophile relative to high field strength elements, sometimes showing negative anomalies in Nb and Ta when normalized to primitive mantle, and rare earth element (REE) chondrite-normalized patterns are enriched in light REE with nearly flat heavy REE segments. Initial 87Sr/86Sr ratios and eNd(i) of the studied rocks range from 0.7040 to 0.7061 and - 2.91 to +4.14 calculated for an age of 80 Ma, respectively. The whole set of geochemical information is compatible with generation of the parental magma by decompression and partial melting of metasomatized peridotite in the mantle wedge that experienced local extension within a regional compressional tectonic regime caused by subduction of Neo-Tethyan oceanic lithosphere. The local extensional conditions may have been responsible for the formation of pull-apart structures in the northern Urumieh-Dokhtar magmatic arc that channeled magma rising towards the surface.