Introducing the exploration and accumulation potential of rare earth elements by the help of metallic elements, heavy minerals and lithologic indices (case study: Lobin – Zardeh region)

The technologic developments in recent four decades have been increasingly expanded the importance and variability of environmental applications of Rare Earth Elements (REE). Since the vast part of their application are so professional, and the great part of the applications are still unknown, the REE exploration progress needs higher technical degrees, in comparison with other elements. REEs form the biggest coherent chemical group of elements of periodic table. Although all 15 REEs along with Y element, are generally similar in geo chemical characteristics, but their global frequency is exclusive for each of them and is not the same at all. The REEs, are the periodic table elements from number 17 up to 85 and are among the internal transition elements. The Lanthanides Appellation are taken from the element number 57, Lanthanum (La). It should be taken in mind that, the chemical characteristics of this group of elements are similar to Lanthanum. Moreover, these elements are not rare at all and not belong to the earth oxides such as Aluminum, Zirconium and Yttrium oxides; as a result the “rare” adjective is a common mistake. While exploring them for the first time, they were observed as oxides accumulations, and since they are somewhat similar to the calcium, magnesium and aluminum oxides; which have been named as earth oxides later; they were called as REEs. It is worth to be mentioned that the amount of cerium in the earth crust is much more that lead and similarly Yttrium is more frequent than Stannum, and it can be said that the rarest earth elements amount, excluding Promethium, are much more than Platinum group elements. According to the one of the famous classification methods, the REEs include Scandium, Yttrium and the Lanthanides group elements and are classified to 2 groups; Light ones (La, Ce, Pr, Nd, Pm, Sm, Eu and Sc), and the Heavy elements (Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y) and according to a general definition the rare earth elements, light rare earth elements and heavy rare earth elements are symbolized by REE, LREE and HREE respectively. The current study evaluates the exploration and distribution pattern of REEs at Tarom heights, limited to the Lobin – Zardeh deposit forming region of Zanjan, Iran. The aim of this study, is recognizing the suitable accumulation zones for REEs, in order to complete the findings of geology organization of Iran, by the help of lithologic, tectonic, geochemical, stream deposits, heavy minerals, RS and aerial geophysics data. After the field investigations, the sampling practices were conducted through 3 environments; stream depositories, rock and heavy metallic zones. Due to the analysis of exploration samples and initial investigation, it was found that the prevailing lithologic feature of region was kalc-Alkaline and Monzonite- Alkaline types, near to the ore formations of Lead, Zink and Copper along with Uranium (poly metallic). Moreover the index minerals and the variety of Paragenesis elements with REEs mineralization such as Anatase, Apatite, Sphene, Ilmenite, Goethite, Magnetite, Hematite, Rutile, Zircon and Y،Sc،Pb،U،Th, elements along with Ce and La have been observed at the region. Finally along with evaluating the findings of current study, the geostatistical methods in providing network maps, have been applied and the overlapping of provided maps and Anomaly and lithologic environments makes the residual elements and metals have been investigated and finally the promising regions map were suggested to be investigated in more developed Supplementary projects for analyzing the economic potential. The future challenges may be evaluation of new and cost effective phytomining methods by planting the native species of a region such as wheat, Soybean and etc. with the minimum pollution level, without needs to heavy investments and pollutant methods, in order to explore these valuable elements. Moreover it is suggested to apply sampling practices through similar mines and indices of mentioned region, by considering the mineral type, mineral analysis and available documents.