New age and geochemical constraints on the origin of Quaternary adakite-like lavas in the Arabia-Eurasia collision zone

摘要: Abstract Adakite-like lavas from the Iranian segment of Arabia–Eurasia collision zone have been considered as partial melts derived a subducted Neotethyan slab, hypothesis that cannot be further evaluated due to lack systematic age and radiogenic isotopic data. Here, we revisit Anar region, Iran where such were reported by providing these data examine their probable origin slab melts. New SIMS zircon U–Pb ages attest eruption at ca. 1 2 Ma, postdating collision. The are characterized dacitic rhyolitic, metaluminous slightly peraluminous trondhjemitic compositions, incompatible element patterns similar continental crustal rocks. Extreme depletion in Nb, Ta, Y heavy REE relative light middle REEs reflects control garnet rutile. Except one sample presumably affected secondary gain Sr, depleted Sr–Nd–Hf compositions Bulk Silicate Earth [( 87 Sr/ 86 Sr) i  = 0.7040 0.7043; eNd( t ) = + 3.2 + 5.3; eHf( ) = + 10.5 + 11.3] indicate magma genesis juvenile source A melt for is very unlikely reason twofold. First, HREE rocks estimated inversed batch melting models assuming pyroxenite residue far too low compared with MORB-like lithologies sediments. Second, MgO, Ni Cr point limited interaction peridotites mantle wedge. Fractionation-related also apparent broadly coeval, mafic precursor magmas without adakitic signature. low-Y low-HREE revealed models, together lavas, can explained lower under eclogite-facies conditions. These most likely high-pressure cumulates root Urumieh–Dokhtar magmatic arc, arc was active Paleogene. Lower might related localized destruction mantle, giving rise temporally spatially associated ultrapotassic magmas. an ‘adakitic province’ near detachment occurred does not hold available observations.