Peshtasar basalts: An example of post-collision basalts in sedimentary basin of Moghan, NW Iran

Journal of earth system science

Reza Zareisahamieh^1¹  Abbasali Amraee^1²  Mohsen Moayyed^2³  Ahmad Ahmadikhalaji^1⁴ 

[1] Department of Earth Sciences, Faculty of Natural Sciences, University of Tabriz, Tabriz, Iran.^2;Department of Geology, Faculty of Sciences, Lorestan University, Khorramabad, Iran.^1;Department of Geology, Faculty of Sciences, Zanjan University, Zanjan, Iran.^3;Geobiotec, Departamento de Geociencias, Universidade de Aveiro, 3810-193 Aveiro, Portugal.^4

关键词: Moghan basin;    Peshtasar basalt;    post-collision arc;    geochemistry;    isotopic analysis;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

With an east–west exposure trend, Peshtasar Complex, which is located in the sedimentary basin of Moghan, northwestern Iran, is lithologically varied. The main constituent minerals are plagioclase, clinopyroxene and iddingsitised olivine in basalts and plagioclase megacryst, clinopyroxene and leucite in tephrite. The studied rocks are plotted in the fields of basaltic trachy-andesite, trachy-andesite and tephri-phonolite in the total alkali-silica (TAS) diagram as well as high-K to calc-alkaline and shoshonite fields. The chondrite normalised pattern of rare earth elements indicates the enrichment of LILE and LREE as well as the depletion of HFSE and HREE. Nb and Ti have a negative anomaly in the spider diagram. Eu/Eu* represents a positive anomaly for Eu indicating the frequency of calcic plagioclase and low oxygen fugacity in rocks. Geochemical parameters and diagrams predict a magmatic evolution via assimilation – fractional crystallisation process. According to the Ce/Yb vs. Ce diagram, partial melting has happened within the garnet–lherzolite field in the depth of ${\sim}$100 km. Based on $^{87}$Sr/$^{86}$Sr, Shahyourdi samples have EM1 sources, whereas Germi and Tazehkand basalts have EM11 sources that are indicative of different mantle sources for basalts in the western Moghan of the central and eastern areas. Basalts are found in active continental margins associated with the post-collision arcs.

【 授权许可】

CC BY