Abstract
The mafic to felsic intrusive rocks of Nay (IRN) are located in the northeast of the central Iranian block. In this study, we present new major and trace element geochemistry, U-Pb zircon ages, and Sr-Nd isotopic data to discuss the origin of the IRN postcollisional units. The oldest units in the Nay area belong to Paleocene?early Eocene volcanic and pyroclastic series including basalt-andesite, latite, dacite, and tuff. These series are crosscut by subvolcanic and granitoid rocks with lithological composition varying from quartz gabbro to K-feldspar granite. The youngest igneous activity is represented by quartz monzodiorite dikes. Hornblende-biotite quartz monzonite from Nay granitoids was dated at 40 Ma (zircon U-Pb). The IRN rocks are metaluminous to peraluminous with high-K calc-alkaline and shoshonitic affinities. They display enrichment in light REEs [(La/Yb)N = 3.79?8.71] and LILEs (such as Ba, Th, Rb, U, and K), with depletion in HFSEs (such as Nb, Zr, Y, and Ti). All rocks have negative Eu anomalies [(Eu/Eu*)N = 0.17?0.88] and relatively flat heavy REE patterns [(Gd/Yb)N = 1.12?1.69]. Granitoids have initial 87Sr/86Sr values from 0.7053 to 0.7061 and ?Nd values from ?1.65 to ?0.02 calculated at 40 Ma. The geochemical composition of IRN rocks along with the low ISr and positive ?Nd values and mantle model ages of 0.6?0.8 Ga indicate that two end-members, enriched mantle and a continental crust, were involved in the magma generation. We argue that the Eocene IRN magmatism occurred as a postcollisional product by asthenospheric upwelling owing to the convective removal of the lithosphere during an extensional collapse of the central Iranian block.
Highlights
Calc-alkaline I-type plutonic rocks, which include subduction-related and collisional magmatic suites, are common in many different convergent tectonic settings
The present study focuses on the mafic to felsic intrusive rocks of Nay (IRN) in the Khaf-Kashmar-Bardaskan volcano-plutonic belt (KKBB) belt, the leaststudied ones among other plutonic rocks in the KKBB belt
Considering the whole dataset, we suggest that the Eocene IRN magmatism occurred as a postcollisional product by asthenospheric upwelling as a result of convective removal of the lithosphere during an extensional collapse of the central Iranian block
Summary
Calc-alkaline I-type plutonic rocks, which include subduction-related and collisional magmatic suites, are common in many different convergent tectonic settings. Some of the other outstanding Eocene magmatic zones in Iran include the Alborz magmatic arc (Aghazadeh et al, 2010; Asiabanha and Foden, 2012), Sabzevar magmatic zone (Verdel et al, 2011; Alaminia et al, 2013; Chiu et al, 2013), Lut-Sistan zone (eastern Iranian suture zone) (Arjmandzadeh et al, 2011, Pang et al, 2013; Arjmandzadeh and Santos, 2014), and Khaf-Kashmar-Bardaskan volcano-plutonic belt (KKBB; north of Lut block; Figure 1) (Karimpour, 2004; Malekzadeh Shafaroudi et al, 2013; Shafaii Moghadam et al, 2015). 4) Granitoids have composition ranging from granodiorite and monzogranite to syenogranite and k-feldspar granite as well as minor amounts of quartz monzonite and monzonite with aplitic dikes They crop out especially in the north of Nay and Uch Palang villages and intruded into the felsic volcanic suites from eastern to western termination (Figures 3A–3C). New alteration and mineralization studies (Almasi, 2016) indicate the occurrence of iron oxide copper-gold (IOCG, Figure 1) mineralization in the Nay area
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
