Structural development of the Naxos migmatite dome
Published:January 01, 2004
This paper presents new structural data on the Naxos migmatite dome, exhumed in the central part of the Aegean Sea in Greece. The dome is cored by anatectic granites and migmatites that have preserved magmatic textures, and it is mantled by a dominantly metasedimentary sequence grading outward from amphibolite to greenschist facies. The elliptical shape of the dome is outlined by a composite transposition foliation in the mantling metasedimentary sequence. The lineation trends NNE-SSW and is associated with top-to-the-NNE shearing. Within the first order dome, kilometer-scale second order domes are evidenced by the orientation of the magmatic fabric, of the syn-migmatitic foliation trends, and by a concentration of enclaves along their margins. A network of granitic veins, structurally rooted in the migmatites, intrudes the mantling metasedimentary sequence. Subvertical granitic dikes, discordant to the foliation, are dominantly oriented parallel or perpendicular to the lineation. These dikes have preserved a magmatic texture and cross-cut partially to totally transposed veins. Kinematic analysis indicates that transposition is consistent with top-to-the-NNE shearing combined with outward rotation of the veins in the mantling metasedimentary sequence during upward migration of the migmatites in the core of the dome. Accordingly, the Naxos migmatite dome is interpreted as a diapir formed in response to a gravitational instability developed in the buoyant, partially molten rocks in a context of regional NNE-SSW extension during gravitational collapse of the Ae gean orogenic wedge.