Geochemistry, petrography and tectono-magmatic setting of Eocene volcanic lavas in the south of Mamoniyeh, Urumieh-Dokhtar magmatic arc, Markazi Province, Iran.

Document Type : Original Article

Authors

1 Department of Geology, Faculty of Science, Lorestan University, Iran

2 geology department, Faculty of Natural Science, Lorestan University, Khoram Abad, Iran

3 Department of Lithospheric Research, Faculty of Earth Sciences, Geography and Astronomy, University of Vienna, Austria

10.22108/ijp.2024.139861.1315

Abstract

The study area is located in the south of Mamoniyeh and the middle part of the Urumieh-Dokhtar magmatic arc. The Eocene volcanic rocks include rhyolite, dacite, trachydacite, trachyte, andesite, trachyandesite, and trachybasalt, exhibiting a major porphyry texture. According to magma series diagrams, these rocks demonstrate a calc-alkaline nature. Primary mantle and chondrite-normalized spider diagrams display enrichment in LILE, depletion of HFSE, and enrichment of LREE compared to HREE, which are characteristic features of calc-alkaline rocks in subduction zones of the continental margin. This enrichment can be attributed to the origin of the magma that formed these rocks, possibly originating from a metasomatized lithospheric mantle above the subduction zone. Analysis indicates contamination with crustal materials and mixing during the ascent of the parent magma. The released fluids from the subducting plate also played a role in shaping the composition of the parent magma, contributing to the tectono-magmatic evolution of the area. It appears that the magma originated from a metasomatized mantle, with a partial melting degree ranging from 20 to 45% garnet-spinel lherzolite to spinel lherzolite. Tectonic zone identification diagrams indicate the rocks' dependence on the volcanic arc environment and the subduction zone, aligning with tectono-magmatic models proposed for the UDMA.

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