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Materials and methods.Fly ash from two lignite-fed power stations of Greece has been utilized as raw material to synthesize zeolitic materials with upgraded adsorption capacity. Two different siliceous fly ash samples (barely Class C -ASTM C618) underwent hydrothermal treatment at fixed solid / liquid ratio (50 g FA / 1 L NaOH) and constant temperature (90°C). The zeolitic products have been characterized for their microstructure, chemical, and mineralogical composition by means of SEM, FAAS, and XRD, respectively. In light of their prospective utilization as liquid-phase sorbents, the specific surface area & porosity of samples were also determined by means of N 2 -porosimetry.Results and discussion. Various types of Na-zeolites have been identified as the predominant phases in the synthetic materials. Selected zeolitic samples were tested for their actual heavy metal-removal capacity by water sampled from lignite mines in Northern Greece. Artificial aquatic samples with known concentration of heavy metals were also used, showing that the synthetic zeolitic materials are able to uptake a wide variety of potential pollutants with up to 100% efficiency. Conclusions.The synthetic zeolitic materials were tested comparatively, showing that the more intense the zeolitic presence in the synthetic materials, the greater the uptake rates for certain groups of trace elements. 113

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The ophiolitic rocks of the Attic-Cycladic crystalline belt are considered of key importance for understanding the Mesozoic tectonic evolution of the Aegean region. Unresolved questions concern their tectono-stratigraphic relationships across the region. The mode of occurrence of the Cycladic ophiolites varies, as they appear as: (a) dismembered blocks (olistoliths) within the supra-detachment units of Paros and Naxos; (b) mélange formations in the upper structural unit of western Samos and Skyros; and (c) meta-ophiolitic mélange in the Cycladic Blueschist Unit (CBU) from central Samos. The trace element geochemistry and Pb-Sr-Nd isotopes of the mafic ophiolitic rocks indicate four geochemical groups: (a) the upper unit metabasites from Paros and western Samos (Kallithea) display an evolved basaltic composition (Mg# 40.2-59.6), with low Zr/Nb values (5-16) and high Ce/Y values (1.3 to 2.6) compared to MORB, indicating island-arc tholeiite affinities; (b) Naxos upper unit metabasalts show spider diagrams patterns indicating ocean island basalt (OIB-type) affinities; (c) Central Samos metagabbros (CBU) are primitive rocks with Back-Arc Basin basalt affinities; (d) the Skyros metadolerites and Tinos (Mt Tsiknias) and S. Evia (CBU) metagabbros, cluster as a separate geochemical group; they exhibit high MgO values (>10 wt %), very low TiO 2 values (0.1-0.2 wt %), Y and Yb, and depleted trace element N-MORB normalized patterns, similar to volcanic rocks formed in modern oceanic fore-arc settings, such as boninites. A combination of the Pb-and Sr-isotopic compositions of Cycladic metabasites indicate that the Pb and Sr incorporated in the Cycladic ophiolites correspond to mixtures of magmatic fluids with seawater (206 Pb/ 204