Petrology and Geodynamics of Young Domes and other Associated Sub-volcanic Bodies of Baladeh

Young volcanic domes and other associated sub-volcanic bodies of Baladeh (Central Alborz) have reached the surface passing through Shemshak Formation (Jurassic). Most of acidic domes and bodies (dacite, rhyolite, and rhyo-dacite) have extruded relatively cold and possess some surficial features. Petrological, textural, and geochemical similarities all over the surface of these domes indicate that they have an endogenous history. According to modern geodynamic models, all of these volcanic rocks are derived from one feeding dike (along Haraz River) which has been dissected after passing the brittle-ductile boundary. Some of the pieces of dikes can be traced in the 2nd and 3rd locations (east of Baladeh village and south of Valashid village). Convergent (collision or post-orogenic) condition is the best scenario for tectonic setting of these bodies based on geochemical data. In addition to partial melting, some other processes such as crustal contamination, gas transfer and to some extent alteration were effective genetic processes. LILE and LREE enrichment patterns indicate low degree of partial melting or end products of fractional crystallization and some crustal contamination (Ba enrichment).