Petrology and geochemistry of pegmatite dikes in the Grizmi and Khajeh Morad granitoids (south of Mashhad, northeastern Iran)

Mesozoic pegmatites from the Grizmi and Khajeh Morad areas (south of Mashhad city, northeastern Iran) are predominantly composed of quartz + feldspar + muscovite +/- biotite, and a variety of minor minerals, including beryl, tourmaline, apatite, garnet, and columbite. They are structurally classified as simple pegmatites, except for the Khajeh Morad samples that are composite pegmatites. Their higher La-n/Sm-n ratio (similar to 2.5) compared to Gd-n/Yb-n (similar to 1.6), and Eu negative anomaly Eu/Eu*< 1 (similar to 0.54) indicate light rare earth element enrichment of the pegmatites. A/CNK> 1 (similar to 1.16) and A/NK> 1 (similar to 1.27) values indicate their peraluminous nature and imply a relationship to S-type granites. Thus, these pegmatites are compositionally similar to peraluminous S-type monzogranites exposed in this area and that were emplaced in a collisional environment. Based on their mineralogy, they belong to the rare element Li-bearing (RE-Li) pegmatite class of the LCT pegmatite family. Regarding the economic geology, these pegmatites are characterized by elevated concentrations of rare elements such as lithium, cesium, and tantalum.