Petrology and Geochemistry of Eocene volcanic rocks, North of Lahrud

Executor of project: Dr. Morteza Khalatbari Jafari 

Project Associates: Eng. Amir Shahriari

2019 

The studied area located in the west of Godah Kahriz, north of Meshkinshahr, Eastern Ardebil province. This area contain the Eocene volcanic rocks, comprise of picrobasalt, basalt, tephrite basanite, trachybasalt, basaltic trachyandesite, phonotephrite, tephrophonolite, trachy andesite and trachyte in compositions. In discriminative diagrams, these lavas show alkaline (transitional- potassic) and shoshonitic trends. In the REE patterns and spider diagrams, they display enrichment of LREE and LILE in relative to HREE and depletion to HFSE (e.g. Ta, Nb, P, and Ti). These evidences suggesting that the origin of the lavas was lithospheric mantle which has been previously metasomatised by subduction components (fluids-melt). In tectonomagmatic discriminated diagrams, the studied lavas plot in magmatic arc with the lithospheric origin or a mixed of lithosphere and asthenosphere. In the Sm to Sm/Yb diagram, these lavas plot in the field of spinel-garnet peridotite. It seems that after convergence of the Arabian plate with Eurasia, the Godah Kahriz Eocene volcanic rocks formed in an extensional-collisional setting.