Les formations néogènes lacustres de l'Attique du Nord -Béotie : stratigraphie, palynologie et tectonique

The stratigraphical-structural framework of Kalamos-Malakassa basin was the result of the intense vertical mouvements occured since Lower Miocene followed by an uplift of its southern part. The following series were distinguished : The Kalamos-Malakassa and Schimatari series, wich consist the lower members of the neogene basin comprised of lacustrine deposits with lignitic intercalations. The Chalkoutsi-Dilessi and Oropos series wich are the lateral transitional phases of the Schimatari and the Kalamos-Malakassa formations respectively. The above mentioned series were affected by four tectonic phases, which are the following : -an initial extentional phase -a compressional phase of NE-SW orientation -an extensional phase of pliocene age having a NE direction. -an extensional phase of quaternary age with a N-S direction.Le cadre stratigraphique et structural du bassin de Kalamos-Malakassa est le résultat d'intenses mouvements verticaux dès le Miocène inférieur suivis par un soulèvement de sa partie Sud. Nous avons pu distinguer les séries suivantes : Les séries de Kalamos-Malakassa et de Schimatari, qui sont les membres inférieurs du bassin néogène. Il s'agit des dépôts lacustres contenant des couches ligniteuses. Les séries de Chalkoutsi-Dilessi et d'Oropos, sont le passage latéral des formations de Schimatari et de Kalamos-Malakassa respectivement. Ces formations sont affectées des phases tectoniques suivantes : -une première phase extensive -une phase compressive orientée environ NE-SW -une phase distensive d'âge pliocène à direction d'extension NE-SW. -une phase distensive d ' âge quaternaire à direction d 'allongement N-S .Mettos A., Ioakim Chryssanthi, Rondoyanni Th. Les formations néogènes lacustres de l'Attique du Nord -Béotie : stratigraphie, palynologie et tectonique. In: Géologie Méditerranéenne. Tome 12-13, numéro 3-4, 1985. pp. 167-174

Dextral strike-slip and normal faulting during middle Miocene back-arc extension and westward Anatolia extrusion in Central Greece

International audiencePresent-day Aegean tectonics is marked by the interplay between Hellenic slab rollback and Anatolia extrusion, explaining the formation of extensional basins and dextral strike-slip faults. We aim to constrain, with structural analysis and low-temperature data, middle Miocene activity of dextral strikeslip and normal faults in Central Greece. We show that onshore middle Miocene basins are controlled by both NW-striking normal faults and NE-striking dextral strike-slip faults. E-striking normal faults developed during the Plio-Quaternary inside pre-existing NW-striking fault zones. Stress tensor calculations show that in middle Miocene, NW-striking normal faults and NE-striking dextral faults are compatible, confirming their coeval activity. In contrast, the Plio-Quaternary stress tensor suggests an almost N-S radial extension, which is not compatible with NE-striking dextral faults in Central Greece. Apatite Fission Track data additionally constrain middle Miocene local cooling near NW-striking normal faults. They also support a difference in the amount of exhumation between Central Greece and the Cyclades, likely accommodated by the Pelagonian dextral strike-slip fault. We propose that in the middle Miocene, the coexistence of dextral strike-slip and normal faults is associated with an almost N-S extension related to trench retreat and an E-W compression related to westward extrusion of Anatolia. The progressive trench curvature during rollback implies block rotation, accommodated by the Pelagonian fault, and subsequent normal fault and extensional stress rotation. During the Plio-Quaternary, a change in extensional direction from NE-SW to N-S implies the formation of E-striking normal faults inside NW-striking fault zone, defining oblique rift systems