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.