Geochemical and Tectonomagmatic Characteristics of the Eocene Rock Units in the Northeastern Novbaran Area

Principal Investigator: Dr. Mohammad Reza Sheikholeslami

Geochemical studies show that the volcanic rocks of NE Nobaran are felsic to intermediate metaluminous rocks with calc-alkaline to sub-alkaline composition which were formed in a magmatic arc on the dynamic continental margin at the edge of the Central Iran Plate.

Composition and texture of the Middle and Late Eocene volcanic, volcaniclastic, and volcanic-sedimentary rocks in the Bijgerd-Kuh e Kharchin area, in the Uromieh-Dokhtar zone northwest of Saveh, Iran, suggest the complexity of the magmatic system that involved multiple eruptions from one or more sources. Hydrated volcanic fragments in hyaloclastic rocks, and the presence of a sequence of shallow and intermediate-depth marine microfossils, suggest that the Middle Eocene units were erupted in a marine basin. The bimodal volcanism of the Late Eocene is distinguished by the presence of four alternating sequences of hyaloclastite lava and ignimbrite. The REE patterns show spatial homogeneity and temporal heterogeneity in the composition of all the Late Eocene sequences, suggesting origination of magma from varying sources that erupted at different times. The trace element distributions of the hyaloclastites and The trace element distributions of the hyaloclastites and ignimbrites are compatible with those evolved through fractional crystallization of the lower and upper continental crust, respectively.

The Alishar area is a valuable zone from the mineralogy and mineralogy point of view. The volcanic rocks of the area have undergone hydrothermal alteration of varying degrees following the rise of magmatic fluids. The most important alterations related to mineralization in the area are argillic, siliceous, iron oxide and propilitic alteration. This feature has caused the formation of mineral manifestations and mineralization of iron, copper, barite, feldspar and kaolin.