Geochemistry and Petrology of Alam -Kuh Intrusive Rocks, West of Kelardasht, Central Alborz

Alam- kuh granitoid intrusion is located in the western part of kelardasht, Central magmatic Alborz structural zone. Alam- kuh granitoid intrusion consist of alkaligranite, syenite, and syenodiorite to monzonite rocks. In the northern part of Alam -kuh intrusion, there are mafic enclaves that represent the magma mixing and mingling process. it consists of plagioclase, quartz, alkali feldspar and biotite minerals. Types of pertite and myrmekite textures associated with granular, microgranular and microgranular porphyry textures observed in these rocks. According to mineral chemistry and whole rock chemistry studies, intrusion rocks are I-type which are typically of shoshonites and are aluminous, metaluminous. Alam- kuh samples are shown enriched in light rare earth elements (LREEs), and La, Rb, Th, Tb elements and depleted in Ba and Zr elements. Based on the major element oxides, tectonically, located in the volcanic arc granitoids (VAG) .Primary magma of district igneous rocks were produced by the melting of the underlying crustal protolith (amphibolite) and (meta-graywacke ), and the basaltic magma derived from the mantle which replaced in the lower crust could be thermal origin for partial melting of crustal source and mixed with crustal felsic magma. According to studis, In the stretching environment of Alborz Magma Bow, Lithosphere mantle and stenospheric mantle, Both were involved in the birth of a mantle with different stocks. Mixing two magmas with mantle and crustal origins and subtraction and crystallization, The most important processes were the development of magma and the diversity of rocks in the region.