OICC Press Iranian Journal of Earth Sciences 2228-785X 18 3 2026 09 30 Geology, Ore-forming Fluid Chemistry, Sr-Nd Isotopes, and Petrogenesis in the Nasim Copper Deposit, NW Bardaskan area, NE Iran 10.57647/j.ijes.2025.17563 EN Touran Ramezani Abbakhsh Department of Geology, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran Mohammad Hassan Karimpour Research Center for Ore Deposit of Eastern Iran, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran Hossein Azizi Department of Mining, Faculty of Engineering, University of Kurdistan, Sanandaj, Iran Saeed Saadat Department of Geology and Petroleum Engineering, Mashhad Branch, Islamic Azad University, Mashhad, Iran Yoshihiro Asahara Department of Earth and Environmental Sciences, Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8601, Japan Behnam Rahimi Research Center for Ore Deposit of Eastern Iran, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran Journal Article 2026 09 30 The Nasim copper deposit is situated in Bardaskan area, northeast of Iran. The geological units include basalt, andesite, trachyandesite, and sedimentary rocks. Conglomerate composed of volcanic fragments and nummulitic limestone has been deposited as a result of subsequent volcanic activity. The majority of trachyte to andesitic rocks that plot within the shoshonite series and exhibit high LREE/HREE and Th/Yb ratios suggest an active continental margin. Elevated Th and Nb values indicate a minor continental crustal assimilation event. Initial 87Sr/86Sr and εNd (i) of the volcanic rocks (t=40 Ma) are 0.7042 to 0.7046 and +4.96 to +5.10 in the Nasim copper deposit, which confirms that it occurred during the continental margin subduction zone. The volcanic rocks were formed in a non-marine environment, and mineralization occurred within the conglomerate bands. The Nasim copper deposit has considered as Manto-type deposit, and chalcocite mineralization occurred after the formation of the conglomerate. The absence of epidote associated with chalcocite suggests low iron content and reducing conditions in the ore-forming fluid of the Nasim deposit. Therefore, the source of mineralization is not magmatic, and further studies on the origin of this deposit should be conducted.