North Aegean core complexes, the gravity spreading of a thrust wedge
Résumé
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-siliconmodels 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.
Domaines
Sciences de la Terre
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