Extract

Metamorphism associated with crustal thickening is well documented in the geological literature, whereas metamorphism during crustal extension has received much less attention. In this paper, we describe the structural and metamorphic evolution of Barrovian style metamorphism on Naxos, Greece. Metapelitic textural evolution and P-T estimates are consistent with decompression during heating. Non-coaxial fabric development occurs as a continuum from the prograde to the retrograde segments of the P-T-t path. We suggest that Barrovian metamorphism on Naxos developed during non-coaxial mid-lower crustal extension.

The island of Naxos is one of the Cycladic group of eastern Greece. These islands form a curved belt of metamorphic rocks, known as the Attic-Cycladic Massif (ACM) which may be traced northwards on to the Greek mainland and eastwards into the Menderes Massif of Turkey. The ACM is a structurally complex nappe pile (Jansen & Schuiling 1976) and metamorphic complexes within the ACM have been subdivided into at least two major tectonic units (Andriessen et al. 1987). A lower unit of Palaeozoic age, containing relict amphibolitegrade Hercynian assemblages is exposed on the island of Ios, and probably on the islands of Naxos and Sikinos (Henjes-Kunst & Kreuzer 1982, van der Maar & Jansen 1983, Andriessen et al. 1987). The upper unit consists of an alternating series of pelitic and psammitic schists and gneisses, metavolcanics and marbles of probable Mesozoic sedimentary age. The geology of Naxos may be divided into three components (Fig. 1).

1 The metamorphic complex. The ACM has undergone intense deformation and metamorphism of Alpine