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Voluminous Tertiary extrusive rocks associated with widespread postcollisional volcanic activities occur on Samothraki island (northeast Aegean Sea, Greece). These rocks have the characteristics of calc-alkaline to high-K calc-alkaline and shoshonite series and can be examined in three main groups based on their field occurrence and geochronology: (1) the “old” group (25 Ma), comprising basalts to latites; (2) the “intermediate” group (22 Ma) of andesites to latites; and (3) the “young” group (22–19 Ma) of latites to rhyolites. Additionally, a “younger vein” (17 Ma) was found with geochemical characteristics similar to those of the intermediate group. Variation diagrams reveal distinct trends between the old and the young groups, whereas the intermediate group generally overlaps the former. The rare earth element (REE) patterns are very similar and tightly clustered, showing quite strong enrichment relative zgroups. MORB-normalized spider diagrams show strong enrichment in large-ion litho-phile elements, and Nb and Ti negative anomalies are characteristic of subduction-related environments. The Sr and Nd isotopic ratios range, respectively, from 0.70876 to 0.70978 and from 0.512184 to 0.512290 for the young group, from 0.70581 to 0.70603 and from 0.512550 to 0.512593 for the intermediate group, and from 0.70501 to 0.70522 and from 0.512651 to 0.512693 for the old group.

A continuous evolution of the magmas for the Tertiary volcanic rocks of Samothraki island is ruled out. Isotope and trace-element modeling shows that the more evolved rocks of the old group were formed through mixing plus fractional crystallization (MFC) (r = 0.3; F = 0.4) involving two melts that originated in different parts of a heterogeneously metasomatized mantle source. The young group evolved through an MFC process during which the basic end-member involved probably originated in the same metasomatized mantle source, and the acid end-member had a strong crustal signature.

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