North Aegean core complexes, the gravity spreading of a thrust wedge

Abstract

The North Aegean core complexes developed in middle Eocene soon after the end of continental block convergence and piling up of the Hellenic Thrust Wedge. They formed during back-arc extension, driven by the Hellenic slab rollback, at the back of the thrust wedge. A series of scaled laboratory experiments was performed to test whether the gravity spreading of a thrust wedge is a suitable process for the development of the North Aegean core complexes during back-arc extension. Wedge-shaped sand-silicon models with variable boundary displacement velocities and different geometries of the upper sand layer were used to study the effects of variations in wedge rheology on the pattern of extension. The models exemplify that extension, either distributed (wide rift mode) or localized (core complex mode), is always located at the wedge rear. Core complex development was favored in models with thicker brittle layer (higher frictional strength) and low stretching rate (lower ductile strength). Both core complex location at the wedge rear and detachment location and dip are interdependent and intrinsically related to the initial wedge shape of the extending system. The experimental model displays striking similarities with the extensional pattern of the North Aegean in terms of (i) location, size, and shape of core complexes as well as their sequence of development and (ii) detachment location and dip. We conclude that it is the initial wedge geometry of the system and the weak nature of the crust at the onset of extension that controlled the extensional pattern of the North Aegean domain.

First-report on Mesozoic eclogite-facies metamorphism preceding Barrovian overprint from the western Rhodope (Chalkidiki, northern Greece)

“…1). In other words, restoring the pre-collapse geometry of the Rhodope, thus virtually closing the SRCC, would bring the NRD and the Chalkidiki block in close proximity (see also Kydonakis et al, 2015). It can be further stressed that due to their present-day position the Chalkidiki block occupied, after restoring the pre-collapse geometry, a position immediately south of the NRD.…”

“…The study area (Chalkidiki block) is shown in a red rectangle. Cross-section re-drawn after Kydonakis et al (2015). (b) Geological map of the Chalkidiki block after .…”

“…The Rhodope is bordered to the north by the Maritza dextral strike-slip fault, to the east by the Middle Eocene to Quaternary Thrace Basin, to the south by the Vardar-Axios-Thermaikos basins which in turn roughly correlate with the Vardar Suture Zone (VSZ) and to the south by the North Aegean Trough. Following Kydonakis et al (2015), we adopt here a simple threefold division where Rhodope is divided, from northeast to southwest, into three tectonic domains: (i) the Northern Rhodope Domain (NRD), (ii) the Northern and Southern Rhodope Core Complexes (NRCC-SRCC), and (iii) the Chalkidiki block (Fig. 1a).…”

From subsurface to surface: a multidisciplinary approach to decoding uplift histories in tectonically‐active karst landscapes

“…The broader area is located in the back-arc of the Aegean subduction zone and in the vicinity of the North Anatolian active fault zone and is thus affected by significant tectonic stresses. This tectonically-active setting (Goldsworthy et al, 2002;Mountrakis et al, 2006;Taymaz et al, 2007;Jolivet et al, 2013;Kydonakis et al, 2015), results in highly fractured carbonate bedrock (i.e., marble) that favors surface karstification and the formation of underground cavities. The Serres fault zone (SFZ) is an extensional fault (Tranos and Mountrakis, 2004), part of the Strymon detachment fault (Kilias et al, 2013) bounding the southwest margin of Mt.…”

Core Complex Segmentation in North Aegean, A Dynamic View

“…Analogue modeling of thrust wedge extension with initial and boundary conditions adapted to the Rhodope example provides a simple first‐order mechanical explanation to the development of core complexes in the Rhodope (Kydonakis, Brun, & Sokoutis, ).…”