G. Pepiper et al., STRUCTURE, GEOCHEMISTRY AND MINERALOGY OF HERCYNIAN GRANITOID ROCKS OF THE VERDIKOUSSA AREA, NORTHERN THESSALY, GREECE AND THEIR REGIONAL SIGNIFICANCE, Neues Jahrbuch fur Mineralogie. Abhandlungen, 165(3), 1993, pp. 267-296
The Verdikoussa granitoid pluton in the Pelagonian zone of northern Th
essaly consists principally of granodiorite, with marginal diorite and
hornblende gabbro. Radiometric dating of biotite indicates a Hercynia
n age near the Carboniferous-Permian boundary. The pluton intrudes a H
ercynian paragneiss series with recumbent folding (Do phase) and is cu
t by ductile shear zones (D1) with NE-trending stretching lineation, d
ated as lower Cretaceous from metamorphic muscovites. This is cut by L
ate Eocene brittle deformation (D2). The granodiorite has subduction-r
elated trace element signatures, but the diorites most closely resembl
e continental flood basalts. Some epidote shows petrographic features
indicating a magmatic origin: with its host assemblage it indicates cr
ystallization at pressures in excess of 6 kbar; hornblende and biotite
are also high-pressure forms. The granodiorite contains K-feldspar me
gacrysts that have systematic Ba variations and distinctive zonation o
f inclusions that suggest a magmatic origin. The granodiorite was empl
aced into an extensional regime as a result of subduction of Paleoteth
ys beneath the Pelagonian zone. The rift-related mafic rocks may refle
ct the resulting opening of a back-arc basin represented by the deep-w
ater Permian rocks of southern Greece and Sicily.