Geochemical evolution and petrogenesis of the eocene Kashmar granitoid rocks, NE Iran: implications for fractional crystallization and crustal contamination processes
Subject Areas : Mineralogy
Rahim Dabiri
1
(Department of Geology, Faculty of Science, Islamic Azad University, Mashhad, Iran)
Mohsen Akbari-Mogaddam
2
(Geological Survey of Iran, North- East Territory, Mashhad, Iran)
Mitra Ghaffari
3
(Department of Geology, Tarbiat Modares University, Tehran, 14115–175, Iran)
Keywords: Contamination, Geochemical Modeling, Petrogenesis, Granitoids, Taknar Zone,
Abstract :
Kashmar granitoids of Taknar zone, in north part of Lut block, intruded into volcanic rocks and consist of granites, granodiorites, monzodiorite and gabbrodiorites. They are composed of mainly plagioclase, alkali-feldspar, quartz, amphibole, biotite and pyroxene minerals. Harker diagram variation, including negative correlations CaO, MgO, FeO, TiO2 and V and positive correlations K2O, Rb, Ba, and Th, with increasing SiO2 and chondrite-normalized REE patterns, suggest that fractional crystallization of gabbrodioritic rocks could have played a significant role in the formation of granites. Their chondrite-normalized REE patterns are characterized by LREE enrichment and show slight negative Eu anomalies. Chondrite-normalized REE modelling indicates that the magma of Kashmar gabbrodiorites were generated with 3–5% of partial melting of a a spinel-lherzolite source. Melting of parental magma located at ~53 km.