The Variation of the stress-and-strain state of the Vuoksi Fault Zone area (Vyborg district)

The stress-and-strain state of the rock massif and kinematic type faults Vuoksi fault zone (Karelian Isthmus) for latest stage tectonic history were determined by field tectonophysical methods. main information was obtained from geological stress/strain indicators, which mostly represented measurements minor slickensides with (the direction relative displacement) on plane. Near zone, systems an orientation close to strike this regional structure are observed. Most widespread strike-slip faults, whereas normal or reverse displacement make up less than a quarter total number faults. STRESSgeol software based method cataclastic analysis used restore state. variable principal stress axes in studied area. two directions maximum compression NE-SW (to ENE-WSW) NW-SE WNW-ESE). deviatory extension subhorizontal directed NNE-SSW NW WNW-ESE) direction. intermediate axis often occupies sub-vertical position. horizontal shear prevails entire lateral displacements also characteristic zone. This part Baltic Shield is significantly different orogenic belts, where, along type, situation dominates. variability area can be preliminarily correlated previously identified “unstable stresses” East European Platform.