Ewolucja sieci spękań ciosowych we fliszu zachodniego Podhala (Karpaty wewnętrzne, Polska)

Abstract

Joint-network evolution in the western part of Podhale Flysch (Inner Carpathians, Poland).A b s t r a c t. The network of joints cutting the flysch deposits in the western Podhale is reasonably regular both in map scale and in individual outcrops. It is formed by five sets having a different orientation with respect to the range of the Podhale Synclinorium, as well as a different age and origin. The oldest diagonal sets (DR, DL) are conjugate and roughly coeval and were formed as “potential shear surfaces” in horizontal beds, whereas their further opening proceeded in an extensional mode. The younger sublongitudinal set (L') comprises extensional joints originated during the early buckling of beds. The transverse set (T), younger than the L'-set, comprises extensional joints formed in relation to the WNW-ESE extension of the Podhale Synclinorium. The youngest longitudinal set (L) originated in an extensional mode in consequence of stress relaxation in the rock massif during postorogenic uplift. Joint density increases in areas involved in relatively strong tectonic disturbances: the zone of tectonic contact between the flysch and the Pieniny Klippen Belt, the zone of contact between the Paleogene deposits, the Tatra Massif and the Biały Dunajec fault zone.