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

Abstract

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 ∼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.

Petrology and geochemistry of Plio-Quaternary high-Nb basalts from Shahr-e-Babak area:Insights into post-collision magmatic processes in the Kerman Cenozoic Magmatic Arc

“…There is not consensus on the timing of the onset collision of the Arabia and Eurasia; it has been suggested the Late Cretaceous (Alavi, 1994;Berberian and King, 1981), the middle Miocene-Pliocene Stöcklin, 1968), and the late Miocene-Pliocene (McQuarrie et al, 2003). Post-collisional alkaline rocks in the UDMA are reported locally as alkaline and shoshonitic OIB like volcanic rocks in Saray (Shafaii Moghadam et al, 2014), Qom-Aran (Amidi, 1977;Emami, 1981), Moghan (Amraee et al, 2019), Saveh (Caillet et al, 1978), Marand (Ahmadzadeh et al, 2010), Ahar (Dabiri et al, 2011), Qom-Baft, and Anar (Ahmadian et al, 2014;Saadat et al, 2010).…”

Neogene Tree Trunk Fossils from the Meshgin Shahr Area, Northwest Iran

“…This area is in the magmatic arc zone of Arabia-Eurasia collision belt [14,15]. The zone includes numerous small-scale magmatic belts that range in age from Cretaceous to Quaternary [16][17][18][19]. The tree fossils are located in the Tarom-Sabalan-Arasbaran (TSA) zone, bounded by the Aras, Astara, and Tabriz faults.…”