Metallogeny of celestite deposits in Iran; implications for future explorations

Abstract

In Iran, celestite deposits/occurrences are found in two structural zones of the (1) Central Iran zone, and (2) Zagros Folded Thrust Belt. The host rock age of the celestite deposits in the world varies from Silurian to Pliocene but in Iran this mineralization’s are specific to the Neogene carbonate-evaporite sequences, which is the (1) Oligo-Miocene Qom Formation in Central Iran zone; (2) the Oligo-Miocene Asmari Formation; and (3) the Early-Middle Miocene Gachsaran-Mishan Formations in the Zagros Folded Thrust Belt, which is known as the youngest host of celestite mineralization in Iran. The marl-carbonate members of the Oligo-Miocene Qom Formation in Central Iran zone hosts the most significant and largest celestite deposits, such as Arvaneh-Aftar, Davazdah-Emam, Siah-Kuh, Madabad, Mazraeh, Nakhjir-Kuh, Kuh-Talhe, Abardej, Kazemabad, Qaleh-Boland, Deh-Namak, Baztab, Paiiez, Pis-Kuh in Jandag area, Tapeh-Gobar, Khoushab-Rood, Zand-e-Fashafoieh, Maranjab, Gand-Aab, Huk, and Makresh deposits. Molkabad deposit in the Central Iran zone, with a reserve of 2Mt, which are typically associated with shallow marine environments is the largest and most important celestite deposit in Iran and also one of the largest celestite deposits in the world. In the Zagros Folded Thrust Belt, the most important celestite deposits located in the Asmari carbonatic Formation in the Bangestan anticline which including Tang-Ban, Tang-e-Nayab, Gonbad-Bardi, Kal-Ahmadi, Posht-Par, Dopar-Nazari, Tortab, Tarak, Gudben, Abolfares, Mokhdan, Konj-e-Konj, Takhtan, Hormuz, Doghonbadan, Abdanan, Pirmored, and Dasht-e-Ahoo deposits. The well-known deposits of Gachsaran-Mishan Formations are the Likak, and Baba-Mohammad deposits. It seems that the evaporite lithology of the Gachsaran Formation can be a suitable environment for celestite mineralization in the Zagros Folded Thrust Belt. According to the Cenozoic celestite mineralization in Iran, it can be concluded the Neo-Tethys oceanic cycle and the geodynamic evolution of the related sedimentary basins played a role in the formation of these deposits. The largest celestite deposits formed during diagenetic replacements and open-space filling processes in coastal carbonate- evaporite sequences. Shallow epicontinental basins are the main geological environment for celestite deposits. Qom back-arc environment and Zagros foreland basin are the main depositional environments for celestite mineralization’s. Saline Sr-rich fluids, shallow depositional environment, regression of sea water, karst-dolomitization process, and semi-arid climate are among the most important factors controlling Iranian celestite deposits. Understanding of the temporal-spatial distribution of celestite deposits in Iran provides valuable insights for exploration and exploitation efforts.