Budowa litosfery na profilu Kraków - Zakopane w świetle wyników modelowania grawimetrycznego

Abstract

Przedstawiono model litosfery, który uwzględnia znane elementy budowy geologicznej, rozpoznanie gęstościowe i wyniki głębokich sondowań sejsmicznych, a jednocześnie jest zgodny z rzeczywistym rozkładem pola siły ciężkości w Karpatach. Uzyskano dobre przybliżenie modelu rozkładu gęstości aż do głębokości rzędu 80 km, uwzględniając hipotezę o kolizji kier. Obliczone krzywe modelowe potwierdzają kształt tzw. minimum grawimetrycznego w Karpatach, co wskazuje na prawidłowość założeń modelowych.

THE STRUCTURE OF LITHOSPHERE IN THE CRACOW-ZAKOPANE PROFILE IN THE LIGHT OF GRAVITY MODELLING

The paper presents results of modelling of the gravity effects along the Cracow - Zakopane profile. This section was selected for that purpose on account of the wealth of the available geological and rock density data from deep drillings situated along it. The Earth crust structure was accepted in accordance with results of interpretation of the V International Deep Seismic Sounding Profile (Fig. 6). Figures 1 and 2 show the final models of sedimentary series and the Earth crust, obtained after introduction of several corrections to preliminary models for making them consistent with measured and calculated gravity effects.

According to the present authors, density of medium between the Moho surface and 80 km depth decreases towards the south (Fig. 3), which gives further support to interpretation of this area in terms of the plate tectonics, in which northern plate plunges beneath the southern in the Peri-Pieniny lineament zone. A gravity depression in the Tatra Mts region (Fig. 5) is related to a horizontal density gradient beneath the Moho surface and location of the latter at larger depths than in areas situated further to the south (Fig. 3). The depression is delineated by the fracture B - B in the south, the Peri-Pieniny lineament in the north, and a discontinuity zone A - A in the east (Fig. 5). In that area, thickness of the Earth crust appears increased and the results of modelling also suggest the possibility of presence of a sedimentary series beneath crystalline massif of the Tatra Mts.