![]() The geochronological, geochemical and isotopic data for the Saray rocks suggest that these Late Miocene magmas were derived from a small degree of partial melting of subduction-metasomatized (subcontinental) lithospheric mantle source in a post-collisional setting. Our melting models suggest residual garnet in the source and are incompatible with partial melting of amphibole and/or phlogopite bearing lherzolites, although the complex geochemical features might indicate the result of mixing between melts produced by different sources or a homogenous melt passing through a compositionally-zoned mantle during multiple stages of partial melting and melt migration. Isotopically, the volcanic rocks define a binary trend, representing 5–8% mixing between the primary mantle and sediment melts. ![]() The highly radiogenic 87 Sr/ 86 Sr and 207 Pb/ 204 Pb isotopic values of the Saray lavas imply the involvement of slab terrigenous sediments and/or a continental lithosphere. The negative Nb–Ta–Ti anomalies for the Saray lavas compare with the features of subduction-related magmatism with negligible contamination with ancient crustal components. ![]() Enrichment in incompatible elements and other geochemical features for the Saray lavas suggest a metasomatized sub-continental lithospheric mantle (SCLM) as the magma source. All the rocks are highly enriched in incompatible trace elements and have identical Sr–Nd–Pb isotopes. Most of clinopyroxene phenocrysts from the volcanic rocks have complex oscillatory zoning, with high Ti and Al cores, low Ti and high Al mantled clinopyroxenes, grading into low Ti and Al outer rims. We report Ar–Ar age data which constrain the age as ca. Post-collisional volcanism in northwestern Iran is represented by the Saray high-K rocks including leucite-bearing under-saturated and leucite-free silica saturated rocks. Major element modeling shows that fractional crystallization and magma flow segregation are the main petrogenetic processes involved in the magmatic evolution of lamprophyre magma, and it is possible to generate syenite magma by these mechanisms. In this metasomatic mantle, it is important to emphasize the strong enrichment of light rare-earth elements, which is higher than those typically associated with basaltic rocks from active continental margins, and corresponding concentrations similar to those determined in lamproitic rocks. Trace element concentrations, such as enrichment in large ion lithophile and strong depletion of some high field-strength elements, indicate a mantle source that was partially modified by a subduction event. Whole-rock geochemical data suggest a metaluminous, ultrapotassic parental liquid, with silica saturation close to the limit of undersaturation. The chemical evolution of the mafic minerals is consistent with increasing oxygen fugacity during late magmatic stages. Clinopyroxene is diopside, and inclusions of phlogopite are analyzed in both clinopyroxene and amphibole phenocrysts. Near liquidus amphibole is edenite, close to the boundary with pargasite, which is enriched in alkalis relative to the other amphiboles (Mg-hornblende and actinolite). Lamprophyric rocks are formed by the early magmatic paragenesis amphibole-clinopyroxene-apatite-phlogopite-ilmenite feldspars are found in the groundmass. The lamprophyres occur mainly as dykes that crosscut the syenitic rocks and occasionally as enclaves. Mica-amphibole-lamprophyres, identified as vogesites, are associated with the Paleoproterozoic Morro do Afonso syenite intrusion in northeastern Brazil.
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