Cabała J., 1996: Active mode of tectonic deformation of Silesian -Cracovian Zn-Pb ore mine area. Tectonophisic of Mining Areas. Prace Naukowe UŒ nr 1602 s. 65-78.

Z powrotem do publikacje Jerzy Cabała

Active mode of tectonic deformation of Silesian-Cracovian

Zn-Pb ore mine area.

Abstract:

In the area between Olkusz and Zawiercie towns, Triassic monoclinal carbonate lithologies "host" deposits of Zn-Pb suphides. These deposits are well recognised by boreholes and mining excavations in some localities. Basing on the research, the occurrence of a deep active tectonic zone of NW SE course was revealed. Some premises were presented, confirming the existence of an important discontinuity in the basement. The tectonic deformations in the Triassic and Jurassic cover were a result of a horizontal basement movement.

Some examples of much complicated tectonic structures: reverse, pivotal and shifted gravity faults were presented. An analysis of tectonic directions enabled to select some areas where faults form non-typical, star-shaped, rhombohedral or en echelon network. An opinion were expressed that some graben and horst structures were created in active way as a result of uplifting within a complicated stress field

Conclusions

Positive, active tectonic movements in the Triassic cover can be a result of a horizontal tectonic movement in the deep basement during Mesozoic era. It is very difficult to present evidences for the existence of that kind of movement, but some premises can be presented:

ˇ in discussed area the NW-SE zone shouid exist which is a contact zone between Upper Silesian Massif (moving during Palaeozoic era) and Little Poland Massif.

ˇ old-Palaeozoic rocks occur in the basement of Mesozoic cover in NE area from a hypothetical discontinuity. This Palaeozoic rocks occur on a different depth than the

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rocks known in southern and western areas. Devonian rocks situated on the line Zawiercie-Siewierz-Klucze-Olkusz-Dębnik form local elevations, clearly distinguished in the Triassic basement morphology.

ˇ signs of volcanism in Myszków and Mrzyglód region (Juskowiak et al, 1978) can confirm the break character of this zone.

ˇ maps of gravity anomaly (Kurbiel, 1979) show a number of NW-SE elongated anomalies in the discussed region.

ˇ occurrence of zinc and lead deposits in the carbonate Triassic and Devonian rocks only in the SW area from a hypothetical zone (Harańczyk 1988, Wodzicki 1987) and the occurrence of Zn-Pb mineralization in Carboniferous and Permian rocks.

Ore mineralization in Triassic and Devonian sediments is clearly related with latitudinal tectonic structures (grabens, half horsts and horsts) The relation between the tectonics and the mineralization exists, but it is difficult to determine a strict relationships between them. A rnajority of faults and tectonic discontinuities within ore pockets is epigenetic in relation to the mineralization. Nevertheless numerous examples shows that the mineralization is developed in fault zones, particularly in their downthrown sides.

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