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

Ludwiniak M.

Przegląd Geologiczny

2008

Vol. 56, nr 12

1092-1099

Thenetwork 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.

Tensor analysis of dislocation-stress relationship based on the extended deformation gradient

Yamasaki K.

Acta Geophysica Polonica

2005

Vol. 53, nr 1

1-12

The dislocation density used to estimate the magnitude of paleostress in rocks has been expressed in terms of a scalar quantity. Dislocations are classified into two types: edge dislocations and screw dislocations. However, the scalar expression of dislocations does not contain information on the type of dislocations. Therefore, we cannot see the effect of stress on the type of dislocations. In other words, we can extract the information related to the magnitude but not the orientation from previous dislocation-stress relationship. Then, we attempted to derive the tensor equation for dislocation-stress field. For this analysis, we introduced the extended deformation gradient tensor, that is, a differential geometrical expression of the ordinary deformation gradient tensor. We assumed that: (1) the higher order terms and spatial derivatives of dislocation density can be ignored; (2) the material is isotropic. We found that our tensor equation for dislocation-stress field is the square root expression of the equation derived from the experimental data of aluminum under static tension. Moreover, we found that the type of dislocation affects the stress field through the difference in the value of coefficients of the dislocation-stress relation-ship.