Geochemistry and petrogenesis of acidic-intermediate dykes from the Yüksekova Complex around Elazığ (Eastern Anatolia, Turkey)

In this study, the geochemistry of acidic-intermediate dykes cutting basaltic volcanics around Elazığ (Osmanağa, Kuşsarayı, İçme and Harput) were discussed. The samples studied are of subalkaline character and are predominantly rhyodacite/dacite and, to a lesser extent andesite in composition. Two main groups can be distinguished for the rocks in the studied region: (1) aphanitic andesite, rhyolite, and dacite dykes (2) phaneritic tonalite, granodiorite dykes. While the Al2O3, TiO2, Fe2O3, MgO, CaO, P2O5, Co, and V contents of the samples decrease with increasing SiO2, Zr, Hf, and Nb show a slight increase. In N-MORB (Normal mid-ocean ridge basalt) and ORG (ocean ridge granite) normalizations, large ionic radius lithophile elements (LILE) (e.g. K, Rb, Ba), Th, and La, are enriched compared to Nb, Zr, Hf, Ti, and heavy REE. All samples are characterized by high Th/Nb and La/Nb ratios (average [Th/Nb]M = 18.3; average [La/Nb]M = 3.5), indicating negative Nb anomalies.Chondrite-normalized patterns are parallel to each other and slightly REE enriched ([La/Sm]N = 1.6-5.4), while medium and heavy REEs have a flat-slightly down-concave pattern. Both the initial Nd and Pb isotopes of the samples are in a narrow range (143Nd/144Nd(i)=0.51285 - 0.51290; 206Pb/204Pb(i)=17.95-18.67, 207Pb/204Pb(i)=15.54 - 15.64, 208Pb/204Pb(i)=37.89 - 38.65), while εNd(i) is between +6.4 and +7.2. All samples have positive and variable Δ7/4, Δ8/4 values ​​(∆7/4Pb = +3.75 to +12.54; ∆8/4Pb = +12.65 to +48.76).High Zr/Nb (43.4-55.7) and εNd(i) values indicate a depleted mantle source. Considering the negative Nb anomalies, the mantle source of the samples can be suggested as a depleted mantle source metasomatically enriched by the slab-derived materials. The relatively high Pb isotopic values over DMM (depleted MORB mantle) can be attributed to the contribution of slab-derived sediment. The isotopic compositions of basaltic lithologies and the intruding acidic-intermediate dykes appear similar. The dykes show no sign of crustal contamination and reflect depleted mantle contribution (high, positive ε values). The negative Nb anomalies, low HFSE and HREE abundances (relative to ORG), and relatively low Th-La enrichment levels of the samples, coupled with high Zr/Nb and εNd(i) values, suggest an oceanic arc environment.