THE WEAK SIDE OF THE ATTIC CYCLADIC CRYSTALLINE COMPLEX (SOUTH AEGEAN, GREECE) (Invited Presentation)

The Attic Cycladic Crystalline Complex (ACCC) in the South Aegean Sea (Greece) is a V-shaped extensional realm formed in the hinterland of the retreating Hellenic subduction zone, where mid to lower crustal rocks were gradually exhumed and are now exposed to the surface. The ACCC hosts spectacular lithospheric scale detachment systems, which form metamorphic core complexes, with all the typical features such as greenschist-facies ductile shear zones, brittle-ductile low-angle normal faults decorated with (ultra)mylonitic rocks overprinted by (ultra)cataclasites. The footwall of the low-angle normtal faults is in many places intruded by syn-extensional granitoids. Locally, the hanging wall is filled with supra-detachment sediments with clasts from the eroded upper plate. While all these features can be observed along the “tense” northern and southwestern sides of the ACCC, where the North Cycladic and the West Cycladic Detachment Systems have acted respectively, the “weak” southeastern side seems to fall rather short. In the past few years, studies on the southeastern islands of the ACCC have identified several extensional structures contributing to the destruction of the nappe pile and the exhumation of the deep-seated rocks.

This work attempts to synthesize recent structural, tectonostratigraphic and geochronological findings from the Santorini, Amorgos Anafi and Kalymnos islands to present the differences and similarities between the detachment-controlled “tense” sides and the “weak” southeastern side of the ACCC. Furthermore, a possible explanation related to the earlier nappe stacking phase is proposed for this diversity.