Abstract
The Southern Rhodope Core Complex is a wide metamorphic dome exhumed in the northern Aegean as a result of large-scale extension from mid-Eocene to mid-Miocene times. Its roughly triangular shape is bordered on the SW by the Jurassic and Cretaceous metamorphic units of the Serbo-Macedonian in the Chalkidiki peninsula and on the N by the eclogite bearing gneisses of the Sideroneron massif. The main foliation of metamorphic rocks is flat lying up to 100 km core complex width. Most rocks display a stretching lineation trending NE–SW. The Kerdylion detachment zone located at the SW controlled the exhumation of the core complex from middle Eocene to mid-Oligocene. From late Oligocene to mid-Miocene exhumation is located inside the dome and is accompanied by the emplacement of the synkinematic plutons of Vrondou and Symvolon. Since late Miocene times, extensional basin sediments are deposited on top of the exhumed metamorphic and plutonic rocks and controlled by steep normal faults and flat-ramp-type structures. Evidence from Thassos Island is used to illustrate the sequence of deformation from stacking by thrusting of the metamorphic pile to ductile extension and finally to development of extensional Plio-Pleistocene sedimentary basin. Paleomagnetic data indicate that the core complex exhumation is controlled by a 30° dextral rotation of the Chalkidiki block. Extensional displacements are restored using a pole of rotation deduced from the curvature of stretching lineation trends at core complex scale. It is argued that the Rhodope Core Complex has recorded at least 120 km of extension in the North Aegean, since the last 40 My.
Highlights
Core complexes originate from the exhumation of middle to lower crustal ductile rocks between separating blocks of the brittle upper crust during large-scale extension (e.g. Crittenden et al 1980; Wernicke and Axen 1988)
From late Oligocene to mid-Miocene exhumation is located inside the dome and is accompanied by the emplacement of the synkinematic plutons of Vrondou and Symvolon
The restoration shows the likely position of Chalkidiki prior to the exhumation of the Southern Rhodope Core Complex (SRCC)
Summary
Core complexes originate from the exhumation of middle to lower crustal ductile rocks between separating blocks of the brittle upper crust during large-scale extension (e.g. Crittenden et al 1980; Wernicke and Axen 1988). The fact that the Moho is rather flat below the core complexes, despite large amounts of extension, suggests that both ductile crust and uppermost mantle are weak enough to allow lateral flow for compensating heterogeneous stretching of the upper brittle crust (Block and Royden 1990; Buck 1991). This may take place if the Moho-temperature exceeds 800°C (Ranalli 2000). Mantle delamination (Bird 1979), back arc environments (Hyndman et al 2005), slab detachment (Gerya et al 2004), triple junction interaction or hot spot migration (Wakabayashi 2004) are other settings where strong thermal softening of crust and mantle may occur
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