Open AccessGeochemistry and Petrogenesis of Basic Paleogene Volcanic Rocks in Alamut Region
Author(s) -
Mehdi Nazari Sarem,
Mansour Vosoghi Abedini,
Rahim Dabiri,
Mohammad Reza Ansari
Publication year - 2021
Publication title -
earth sciences research journal/earth sciences research journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.181
H-Index - 15
eISSN - 2339-3459
pISSN - 1794-6190
DOI - 10.15446/esrj.v25n2.74025
Subject(s) - petrogenesis , geology , geochemistry , basalt , volcanic rock , andesite , metasomatism , rift , rhyolite , phlogopite , mantle (geology) , petrology , volcano , tectonics , paleontology
Structurally, the study area belongs to the tectonic range of the Central Alborz. The rocks were analyzed to detect main elements as well as rare and rare earth elements. Based on microscopic studies, the rocks in the region include basalt, trachyandesite and basaltic andesite with alkaline geochemical properties. According to geochemical studies, the early magma was affected by Nb, Ti, Ta, Eu negative anomalies, the enrichment of Rhizosphere rocks of rare earth elements (LRRE), high LREE/HREE ratio and low K/Nb ratio and high ratios of Th/Nb, La/Nb, Ba/Nb, Zr/ Nb magmatic contamination. The early basaltic magma has been formed of a garnet lherzolite mantle with phlogopite/pargasite by metasomatism at a pressure of 2.5-5.3 GPa at depths of more than 80-150 km. Structural evidence suggests the formation of these volcanic rocks in intercontinental rift zones. The formation of these rocks can be attributed to the effects of intercontinental extensional phases in deep faults during Eocene Alpine orogeny phases.