FORMATION OF THE NAXOS MIGMATITE DOME (CYCLADES)

The aim of this contribution is to describe the structural record of the Naxos migmatite dome formation. The island of Naxos is characterized by the juxtaposition of metamorphic rocks and Late Oligocene-Early Miocene to Upper Pliocene sedimentary basins along a low-angle detachment. Migmatites and anatectic granites, dated at ca. 15 Ma (Keay et al., 2001, Tectonophysics 342), appear in the core of a structural dome surrounded by a sequence of metasedimentary rocks. The dome shape is underlined by the magmatic foliation of the anatectic granite and by the foliation in the metasedimentary unit. The metasedimentary rocks contain a network of granitic veins that are structurally connected to the migmatitic dome. This network comprises (i) veins that have preserved magmatic textures and are discordant to the foliation and (ii) veins that are characterized by solid state deformation and appear transposed to various degrees in accordance to the main foliation. Discordant veins are dominantly vertical and oriented parallel and perpendicular to the regional amphibolite-facies stretching and mineral lineations. Transposed veins are shortened perpendicular to the regional foliation and the ones that are oriented perpendicular to the lineation are affected by top to the northeast shear bands.

These features suggest that the granitic veins emanated from the migmatites and intruded the metasedimentary sequence while it was affected by deformation as a consequence of progressive formation of the migmatite dome and top to the northeast regional shearing. This strain pattern is likely the result of the combined effect of buoyancy-driven gravitational instabilities developed in a partially molten mid- to lower crust and regional gravitational collapse of the Aegean orogenic wedge.