Lavrion area is the westernmost part of the Attic-Cycladic crystalline belt (ACCB). Metabasitic rocks from the Upper Tectonic Unit of the Lavrion area occur as  greenschists and blueschists. Major and trace element relations against Mg# show a systematic increase in TiO2, Fe2O3*, Na2O, Zr, Y, V, La and Yb abundances and decrease in Al2O3, Ni and Cr with decreasing Mg#, where the blueschists always exhibit a more evolved basaltic composition. The greenschists are characterized by LREE-depleted chondrite-normalized REE patterns and Zr/Nb values that range from 15 to 24. The blueschists are characterized by slightly LREE-enriched chondrite-normalized REE patterns and lower Zr/Nb ratios (6.6-11.3). Both types of the metabasites share common geochemical features like HFSE flat patterns slight positive Nb anomalies with La/Nb<1. The protoliths of the metabasites seem to evolve through fractional crystallization processes following a normal tholeiitic trend. The observed Zr/Nb vs. Ce/Y ratios imply an almost continuous spectrum of magma compositions for their protoliths. The REE patterns of the studied metabasites cannot be explained only by fractional crystallization processes. Therefore either partial melting of a heterogeneous mantle source or assimilation of sedimentary or gneissic material can produce the observed REE pattern, with the former process being the dominant. Concluding we interpret the protoliths of the metabasites as products of a mature back-arc basin similar to that occurring in Syros, Sifnos and Tinos islands, all parts of the ACCB.

3. Petrogenesis of Pegmatites in and around Owala-Kaikawela, Sri Lanka (Amaraweera, T.N.H.G, Pitawala, A, Fernando , G.W.A R. and Hauzenberger, Christoph A)

Two groups of pegmatites of granitic to syenitic compositions can be distinguished in the Owala-Kaikawela area in the central part of Sri Lanka. The syenitic pegmatite is a mineralogically zoned body composed mainly of pertitic feldspars with fluorite while the granitic pegmatites are characterized by irregularly zoned feldspars. Mineral assemblages and field relationships of these pegmatites provide conclusive evidence that they may have derived from partial melting (anatexis) of crustal materials and parental magma had been fractionated into fluoride-poor and -rich fractions at the initial stage.

Chemical fractionation of the parental melt during the emplacement is supported by the distributions of trace elements in K-feldspars. The distributions of trace elements in K-feldspars indicates that the pegmatites from this area are infertile pegmatites derived from a single magmatic source. Enrichment of compatible elements in fluorite bearing syenitic pegmatites and of incompatible elements in granitic pegmatites clearly indicate that the syenitic pegmatite were derived at an early stage from the parental melt while volatile absent and low silica granitic pegmatites are a product of late residual portions of the parental melt.

4. Geochemistry of basement rocks from SE Kenya and Tanzania Mozambique Belt and Usagaran Belt)