The Orava Deep Drilling Project and post-Palaeogene tectonics of the Northern Carpathians

Jan Golonka, Paweł Aleksandrowski, Roman Aubrecht, Józef Chowaniec, Monika Chrustek, Marek Cieszkowski, Radosław Florek, Aleksandra Gawęda, Marek Jarosiński, Beata Kępińska, Michał Krobicki, Jerzy Lefeld, Marek Lewandowski, František Marko, Marek Michalik, Nestor Oszczypko, Frank Picha, Michal Potfaj, Ewa Słaby, Andrzej Ślączka, Michał Stefaniuk, Alfred Uchman, Andrzej Żelaźniewicz

Abstract


Problematyka głębokiego wiercenia na Orawie a popaleogeńska tektonika Karpat Północnych

This paper presents an insight into the geology of the area surrounding the ODDP proposed drilling site, and the structural development of the Carpathians in post-Palaeogene times. Since the deep drilling is proposed to be located in the Orava region of the Northern Carpathians, on the Polish-Slovak border, the structure and origin of the Neogene Orava Basin is also addressed in the paper.
The outline of geology of the Carpathian Mountains in Slovakia and Poland is presented. This outline includes the Inner Carpathian Tatra Mountains, the Inner Carpathian Palaeogene Basin, the Pieniny Klippen Belt, the Outer Carpathians, the deep structure below the Carpathian overthrust, the Orava Basin Neogene cover, the Neogene magmatism, faults and block rotations within the Inner and Outer Carpathians, and the Carpathian contemporary stress field.
The outline of geology is accompanied by the results of the most recent magnetotelluric survey and the detailed description of the post-Palaeogene plate tectonics of the circum-Carpathian region. The oblique collision of the Alcapa terrane with the North European plate led to the development of the accretionary wedge of the Outer Carpathians and foreland basin. The northward movement of the Alpine segment of the Carpathian-Alpine orogen had been stopped due to its collision with the Bohemian Massif. At the same time, the extruded Carpatho/ Pannonian units were pushed to the open space, towards a bay of weak crust filled up by the Outer Carpathian flysch sediments. The separation of the Carpatho/Pannonian segment from the Alpine one and its propagation to the north was related to the development of the N-S dextral strike-slip faults. The formation of the West Carpathian thrusts was completed by the Miocene time. The thrust front was still progressing eastwards in the Eastern Carpathians. The Carpathian loop including the Pieniny Klippen Belt structure was formed. The Neogene evolution of the Carpathians resulted also in the formation of genetically different sedimentary basins. These basins were opened due to lithospheric extension, flexure, and strike-slip related processes. A possible asteno- sphere upwelling may have contributed to the origin of the Orava Basin, which represents a kind of a rift modified by strike-slip/pull-apart processes. In this way, a local extensional regime must have operated on a local scale in the Orava region, within the frame of an overall compressional stress field affecting the entire West Carpathians.
Nevertheless, many questions remain open. Without additional direct geological data, which can be achieved only by deep drilling under the Orava Deep Drilling Project, these questions cannot be fully and properly answered.

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