​The concept ofan ‘Azores mantle plume’has been widely debated, and the existence of an Azores hotspot questioned. In an effort to shed new light on this controversy, we present He isotope and major, trace and volatile element compositions for basaltic scoriae from five mono- genetic cones emplaced along the fissure zone of Pico Island, the youngest island of the Azores archipelago. The bulk scoriae and lavas are moderately alkaline basalts, and their He isotope ratios, determined on olivine crystals, vary between 10·2 and 11·1±0·1 R_a. In contrast, melt inclusions hosted in olivine (Fo_76-83·5) span a large range of compositions (K₂O=0·7-1·7 wt %; Ce=32-65ppm; Nb=21-94 ppm), which extends the compositional field of lavas erupted along the Pico fissure zone. This chemical evolution is pre- dominantly controlled by polybaric fractional crystallization. Most melt inclusions share similar enrichments in large ion lithophile and light rare earth elements, and trace element ratios (La/Sm, La/ Yb, Sr/Nd, Ta/Th, Zr/Y) with their bulk-rocks. Only a few of them differ in their lower contents ofincompatible elements and La/ Sm, Li/Ta andNa/Kratios, a feature that is ascribed to distinct con- ditions ofmelting. As a whole, the melt inclusions preserve high and variable volatile contents, and contain up to 1·8-2·0 wt % of H₂O and 0·4 wt % of CO₂. The total fluid pressures, retrieved from the dissolved CO₂ and H₂O concentrations, and the P_CO2 from fluid inclusions, indicate magma ponding and crystallization at the crust-mantle boundary (ca. 18km deep).The H₂O/Cl and H₂O/Ce ratios in the inferred parental undegassed basalts of the Pico fissure zone average 0·036±0·006 and 259±21, respectively. The latter value is significantly higher than that reported for typical mid-ocean ridge basalts from the southern Mid-Atlantic Ridge, but is similar to pub- lished ratios for submarine undegassed basalts from the Azores plat- form. Combining the calculated compositions of Pico primary magmas formed by low degrees of melting with recent geophysical data for the Azores, we propose a model forAzores magma generation involving the decompression melting of a water-enriched mantle domain (H₂O=680-570 ppm) with an estimated temperature excess of ≤120ºC with respect to the Mid-Atlantic Ridge.