The Neogene post-collisional volcanism in eastern Iran is represented by the Sikh Kuh and Bobak high-Na rocks including trachybasalt, trachyandesite, trachydacite, and dacite. We report whole rock geochemistry and Nd–Sr isotopic data which constrain the characteristics of the mantle source. The rocks are highly enriched in incompatible trace elements, suggesting a metasomatized subcontinental lithospheric mantle (SCLM) as the magma source. Felsic rocks record abundant petrographic evidence, major and trace element data, and isotopic (⁸⁷Sr/⁸⁶Sr(i) = 0.70727–0.70902) signatures indicative of fractional crystallization, and potentially, crustal assimilation. Such processes however, have not significantly affected the isotopic signatures (⁸⁷Sr/⁸⁶Sr(i) = 0.70417–0.70428) of the mafic members, suggesting that they are derived from a mantle source. The geochemical and isotopic data for the Sikh Kuh and Bobak volcanic rocks suggest that these Neogene magmas were derived from a small degree of partial melting (~ 2–10 vol%) of a spinel-bearing subcontinental lithospheric mantle source in a post-collisional setting. The generated more unfractionated mafic magmas erupted during an episode of extensional tectonics, presumably caused by extension that followed Eocene collision between the Lut and Afghan continental blocks. These melts interacted with continental crust during ascent, experiencing crystal fractionation, and crustal assimilation, to produce more evolved felsic volcanic rocks.

伊朗东部新近纪碰撞后火山活动以 Sikh Kuh 和 Bobak 高钠岩石为代表，包括粗面玄武岩、粗面安岩、粗面英安岩和英安岩。我们报告了限制地幔源特征的全岩地球化学和 Nd-Sr 同位素数据。岩石富含不相容的微量元素，表明岩浆来源为交代次大陆岩石圈地幔 (SCLM)。长英质岩石记录了丰富的岩相学证据、主要元素和微量元素数据以及同位素 ( ⁸⁷ Sr/ ⁸⁶ Sr(i) = 0.70727–0.70902) 指示分步结晶和潜在地壳同化作用的特征。然而，此类过程并未显着影响同位素特征（⁸⁷ Sr/ ⁸⁶Sr(i) = 0.70417–0.70428) 的基性成员，表明它们来自地幔源。Sikh Kuh 和 Bobak 火山岩的地球化学和同位素数据表明，这些新近纪岩浆源自碰撞后环境中含尖晶石的次大陆岩石圈地幔源的小程度部分熔融（~ 2–10 vol%） . 所产生的更多未分馏基性岩浆在一次伸展构造期间喷发，这可能是由于始新世 Lut 和阿富汗大陆块之间碰撞后的伸展造成的。这些熔体在上升过程中与大陆地壳相互作用，经历晶体分异和地壳同化，产生更多演化的长英质火山岩。