engleski

The correlation between the stress field in the Pannonian and Dinaridic-Adriatic part of Croatia

The presented map of stress fields is the result of field observations and investigations carried out within the framework of producing the tectonic map of Pannonian – Dinaridic – Adriatic parts of Croatia. Orientation and distribution of stress fields are given by the geotectonic position of the area investigated, being situated between the southern part of the Euroasian continent and the northern part of the Adriatic carbonate platform (AdCP) as a part of the African plate (Dercourt et al., 2000). The present-day structural-geomorphological relations of the Pannonian – Dinaridic – Adriatic belt are part of a mosaic subject to polyphase structural deformations. The Adriatic micro plate unites a number of blocks separated from their basement-continental crust (Italy, Sicily, and Dinarides), that was pushed, like a tectonic wedge, into the southern rim of the European continent (Channel et al., 1979). During the convergence, the Adria collides, with its northern rim, with the southern part of the European continental border (Laubscher, 1989), whereby it comes to the disintegration of structures, first by overthrusting toward the south, i.e., by transpression deformations of the blocks in the Southern Alps. The main dividing line between the Western, Central, and Eastern Alps versus the Southern Alps as a part of Apulia, is the Periadriatic lineament (Laubscher, 1983 ; Schmid, 1996, etc.). The northern part of Slovenia, the region of Zagorje-northwest of Mt. Medvednica (Zagreb Mountain), forms a transitional zone toward the Pannonian-Dinaridic belt, situated to the south and east. This zone is characterized by a system of lineaments that delimit a number of heterogeneous structural units (Haas et al., 2000), formed by transpressional stress fields. The Pannonian-Dinaridic belt is characterized by kilometer-sized compression structures, formed by the NE-SW oriented stress during the main orogenic phases (from the end-Cretaceous to the Eocene). Within this belt, there are two tectonic units – the Adriatic Sea (foreland) unit and the continental Dinaridic (hinterland) unit – that are divided by a reverse-overthrust zone striking along the coastline and coinciding with the deepest part of the Moho discontinuity (Aljinović et al., 1987). To the north, the Dinaridic belt is separated by a north verging reverse fault zone (Royden et al., 1983). Such structural tectonic relations persisted undisturbed up until the Neogene-beginning of the Miocene, when in the broader Mediterranean area CCW rotation of structures took place (Alvarez 1972 ; Catalano and D’ Argenio, 1978 ; etc.). The change of the stress orientation into the N-S direction results in the opening of the most important fault zones both in the Pannonian Basin (Jamičić, 1995) and in the Dinaridic belt. The most important fault zone within the Dinaridic belt consists of the transpression faults Karlovac— Knin and Šibenik— Lastovo (Prtoljan et al., 2005), which separate the paleodynamic units, and, in the younger phases of tectonic activity, whole tectonic blocks, or parts of them, underwent the CCW 30-400 , in extreme cases even up to 600 , rotation along these faults. Recent orientation and movements of Pannonian-Dinaridic structures, as well as the entire Pannonian Basin and Carpathian Mountain Chains, coincide with the converging of the European and African continents (EUREF, 2005). Synchronously with it, the Dinaridic (hinterland) unit and the Adriatic (foreland) unit also converge (Altiner, 2001), accompanying the gradual increase of the seismicity at the broader regional scale (Favali et al., 1993 ; Oldow et al., 2002 ; Herak et al., 2005).

stress; pannon; dinarides; structures; transpression; Croatia

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