TY - JOUR ID - 54602 TI - Petrogenesis of Plio-Quaternary Post-Collisional Potassic and Ultra-Potassic Rocks in Northwest Marand JO - Scientific Quarterly Journal of Geosciences JA - GSJ LA - en SN - 1023-7429 AU - Ahmadzadeh, G. AU - Jahangiri, A. AU - Mojtahedi, M. AU - Lentz, D. AD - Department of Hydrology, Agriculture Faculty, University of Mohaghegh Ardabili, Ardabil, Iran AD - Department of Geology, Natural Science Faculty, University of Tabriz, Tabriz, Iran. AD - Department of Geology, University of New Brunswick, Canada. Y1 - 2011 PY - 2011 VL - 20 IS - 78 SP - 79 EP - 86 KW - Ultrapotassic KW - Leucite KW - Subduction KW - Metasomatism KW - Marand DO - 10.22071/gsj.2010.54602 N2 - In this paper the study of Plio-Quaternary post-collisional magmatism in northwest of Iran and northwest of Marand is considered. The studied Potassic and ultrapotassic (UP) alkaline rocks were erupted at northern part of Urumieh-Dokhtar magmatic arc (UDMA). The studied rocks dispaly microlithic porphyritic texture with phenocrysts of clinopyroxene, leucite, and plagioclase ± biotite ± olivine. The UP volcanic rocks are mostly silica undersatuated with normative nephline, high Mg# and high K2O/Na2O ratios. They characterized with significant enrichment in LILEs and LREEs and depletion in high field strength elements such as Nb, Ta and Ti. Exhibit high Ba/Nb (41-60) and Ba/Ta (682-1139) ratios, which are a typical feature of subduction. With considering end of subduction (upper cretaceouse) and stratigraphic age of studed rocks (plio-quaternary), we can say that these rocks has formed in post collisional environment and metasomatic mantle due to addition of volatiles and incompatible elements lead to enrichment of these magmas. And in fact we can say that the subduction properties of these rocks inherited from an ancient subduction. On the otherhand, high contents of LILE such as Th and Ba and Ba/Nb, Ba/Ta ratios indicate the involvement of crustal components in genesis of these rocks by addition of crustal components to source and contamination through ascent of magma. Rare earth elements modeling indicate that they can be generated from low degree partial melting of lithospheric mantle with garnet-spinel peridotite source. UR - http://www.gsjournal.ir/article_54602.html L1 - http://www.gsjournal.ir/article_54602_be0094eb0863154ef74db386594b4c6a.pdf ER -