Plagiogranites in the hellenic ophiolites

Plagiogranites have been studied from the areas of Guevgueli, Samothraki Is land, Koziakas Mountains, Rhodes Island and Crete. They are typical trondhj emites (plus Qz-diorites in Guevgueli) while an unusual Qz-monzonite (geoch emically defined) occurs at Rhodes. Furthermore, a leucogranite assemblage is associated with the plagiogranite in Samothraki; it has been derived by partial melting of the plagiogranite during a collision event. Geochemical results show that all the plagiogranitic rocks are differentiates of a mafi c magma. In addition, at Guevgueli and Samothraki, a subsequent filter pres sing process resulted in flowage of the leucocratic melt into cracks of the country rocks with the formation of a net-veined structure. The plagiogran ites from Samothraki, Koziakas and Crete have chemistries similar to Volcan ic Are Granites, whereas the Guevgueli plagiogranite has an affinity closer to Ocean Ridge Granites. However, this variation is attributed to heteroge neities of the subducted lithosphere since all the above plagiogranites are associated with ophiolites of marginal basin origin.