Introduction to the geology and mineralogy of pegmatites located south of Mashhad (first report of Li-bearing pegmatites from Iran)

The granites south of Mashhad are located in the north-east of Iran and occur in the suture zone between the Binalud and Kopeh Dagh areas. These S-type granites are peraluminous with an Upper Triassic Age and include intersecting pegmatites. These pegmatites are homogenous and show simple mineralogical combinations which include K-feldspars (microcline and orthoclase), plagioclase, quartz, micas (biotite, muscovite and lepidolite), tourmaline(elbaite, dravite, and schorl) and garnet (almandine-spessartite). The pegmatites south of Mashhad belong to the LCT (Lithium-Cesium-Tantalum) and MSREL-Li (Muscovite- REE-Li).The Li-content of these pegmatites ranges between 202-1653 ppm and the ratios K/Cs, K/Rb and Al/Ga are high which indicates a low level of differentiation. The Mg/ Li ratio in these pegmatites lies between 0.2-12.6. All the element ratios indicate that pegmatites are low evolved.