Geochemistry and petrogenesis of Cretaceous volcanic rocks from the south and southwest of Germi city (Northwest of Iran)

Abstract

The Cretaceous volcanic rocks (Andesite and basaltic andesite) in the northwest of Iran, south - southwest of the Germi city (Ardabil province), have considerable outcrops with northwest - southeast trend. The textures in the studied rocks are porphyry, hyalomicrolitic and glomeroporphyry and the main mineral is plagioclase with pyroxene, brown amphibole and biotite as accessory minerals. The rocks under study have calc-alkaline nature and have been crystallized from a magma experienced fractional crystallization. In the primitive mantle normalized spider and chonderite normalized rare earth elements diagrams. The studied rocks are characterized by LREE and LILE enrichment and depletion in HFSE as well as spikes in Pb and Eu. The overall features are compatible with subduction-related. The Cretaceous volcanic rocks under study have been generated in an active continental margin.

Keywords

• volcanic rocks
• subduction
• continental magmatic arc
• spinel garnet lherzolite
• Cretaceous
• Germi
• Talesh zone