Mohsen Mortazavi Ravari, Fariba Jamshidi, Abbas Asiabanha,
Volume 31, Issue 3 (10-2023)
Abstract
The Late Cretaceous basaltic magmatism in northern part of the Urumieh-Dokhtar Magmatic Arc (UDMA) includes subalkaline (transitional) basalts and basaltic andesites; which are formed in associated with various pyroclastic and sedimentary rocks. These rocks are charactrized by similar geochemical patterns including enrichment in light rare earth elements (LREEs), large ion lithophile elements (LILEs), and depletion in high field strength elements (HFSEs; e.g., Nb, Ta, Ti). These geochemical evidence indicates magmatism related to volcanic arcs and subduction setting. In addition, the nearly flat heavy rare earth element (HREE) patterns are similar to that of the oceanic island basalt (OIB). These mafic magmatic rocks are characterized by a mantle dominated composition, evidenced by (87Sr/86Sr)i ratios of 0.70404–0.70414, and uniform positiveεNd(t) values of 1.00–4.14. The trace-element and isotopic modelling indicate that the studied basaltic rocks resulted from partial melting of metasomatized lithospheric mantle wedge at the garnet–spinel stability depth in transitional zone. The magmatism in the study area more likely occurred in an incipient volcanic arc setting due to asthenospheric upwelling in response to lithospheric extension during slab retreat 80 million years ago.
