Strain geometry and kinematics along the central Pindos Thrust Belt in Northern Greece: implications for the structural evolution of the External Hellenides

The Pindos Thrust Belt (PTB) represents the intensively folded and thrusted sedimentary sequence deposited in the Pindos basin along the western margin of the Pelagonian microcontinent. Pindos Thrust Belt expands, from northern Greece to the southern Greece on the Peloponnesus, exhibiting a NW-SE strike, thereafter it turns in an E-W striking direction. Its north continuation in Albania is represented by the Crasta –Cukali Zone. PTB is enveloped between the Gavrovo Zone, to the West and the Pelagonian nappe system to the East. The zone accommodates a succession of continuous Mesozoic deep sea sediments, comprising cherts, clay- silt- stones and pelagic limestones. An Upper Cretaceous to Eocene flysch terminates the sequence. Orogenic processes (Neohellenic Stage) associated with plate convergence during Tertiary caused compression and crustal thickening, generating folding and thrusting (PTB) followed by normal faulting and extension.
   Based on a quantitative analysis along the N-S striking segment of PTB in Northern - Central Greece we present structural data concerning the Tertiary deformation regime of PTB. Strain and paleostress tensor analysis of deformation were also performed on selected outcrops.
   Data analysis point to the following deformation styles to have affected the PTB:
   An early D1 deformation style of Paleocene to Eocene age, represented by asymmetrical, angular, tight folds with axes bearing a N-S to NW-SE present day orientation. D1 is associated with the progressive westward to south-westward propagation of thrusting of the external Hellenic orogenic wedge over the Adriatic platform. Back-thrust structure geometry with NE -ward vergency is also recorded. Striaetion lineation on the thrust planes exhibits a ENE-WSW to NNE-SSW strike. Paleostress analysis shows a subhorizontal, E-W to NE-SW trending maximum main axis σ1 and a subvertical minimum main σ3 -axis.
   A late D2 deformation style of Oligocene –Miocene age, overprints the former D1 structures, producing WNW-ESE to E-W trending compressional structures, such as asymmetrical steep folds and thrust faults.
   Sense of movement is evaluated mainly towards SSW to S. Striaetion lineation along thrust planes exhibits progressively a NNE-SSW to N-S trend. NW-SE dextral and NE-SW sinistral trending strike slip faults, associated with the D2 compressional structures, induced a SE- or NW-ward orogen parallel motion. Furthermore, some of the D1 thrust faults were reactivated during the D2 as strike slip faults. Paleostress analysis shows a subhorizontal maximum main axis σ1 in a N-S to NNE-SSW direction during D2 event.
   Both in map and outcrop scale curvature of D1 structure trace, as well as the orientation geometry of the D1 and D2 structures, imply a continuous deformation regime during Tertiary time under oblique plate convergence and a transpression related strain field.