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Content available remote Gravity measurements in the Pieniny Klippen Belt (Western Slovakia)
EN
The examined area is situated in the Púchov section of the Pieniny Klippen Belt (PKB) in western Slovakia. The main aim of our research was to broaden the present knowledge on geological structure of the PKB and on its tectonic connection to the surrounding regional units using the geophysical methods.The profile gravity measurements consist of two parallel profiles named prof_1 and prof_2 of roughly NNW-SSE direction. The eastern section prof_1 has a length of 6.36 km; the western profile prof_2 is about 3.84 km long. Measurements were carried out at intervals of 20 meters (overall 506 points were gauged) by gravimeters Scintrex CG3 and CG5. The acquire data were processed into the Bouguer gravity anomalies. The software package GM-SYS (Geosoft) was applied for the gravity modelling and the final geological-geophysical sections represent distribution of the lithological members with their specific density parameters (density values were determined by the own laboratory measurements of rock samples collected along the profiles). The density modelling was also based on the results obtained by the geoelectrical exploration (vertical electric sounding and resistivity profiling), new surface geological mapping and borehole interpretation (continuously cored bores MIK-1 and MIK-2). Presented detailed gravity measurements reflect density differences between klippen (rigid limestone blocks) and their mantle (predominant marlstone) and they demonstrate that the primary fold-nappe system of the PKB was destructed by the subsequent deformation, resulting in the formation of the positive flower structure and backthrusting. Summing up, the new density modelling confirmed complex geological structure of the studied area and helped us to better interpret the tectonic evolution of the PKB.
EN
Although no undoubted oceanic crustal rock complexes of Penninic affinity participate in the present surface structure of the Western Carpathians, indirect lines of evidence suggest prolongation of the South Penninic-Vahic oceanic tract into the ancient Carpathians. The sedimentary record of both the syn-rift and syn-orogenic clastic deposits reveal their origin between the outer Tatric (Austroalpine) and the inner Oravic (Middle Penninic) margins. The rifting regime is exemplified by the normal fault-related scarp breccias of the Jurassic Borinka Unit in the Male Karpaty Mts., which are characterized by local, gradually denuded source areas. Two other regions provide examples of a contractional regime, both related to shortening and closure of the Vahic oceanic domain. The Belice Unit in the Povazsky Inovec Mts. includes Upper Jurassic-Lower Cretaceous eupelagic, mostly siliceous deposits and a thickening-upwards Senonian sequence of turbiditic sandstones, conglomerates and chaotic breccias. It is inferred that this succession represents the sedimentary cover of oceanic crust approaching a trench, its incorporation in the accretionary complex and finally underthrusting below the outer Tatric margin. In the Oravic units of the Pieniny Klippen Belt, deep-marine conglomerate/breccia bodies with olistoliths indicate collision-related thrust stacking that started from the Maastrichtian (Gregorianka Breccia of the Sub-Pieniny Unit) and terminated with the Lower Eocene Milpos Breccia in the Saris Unit. In addition, a tentative recycling scheme of “exotic” clastic material from mid-Cretaceous conglomerates of the Klape Unit to various Klippen Belt units is outlined. This material is considered to be unrelated to the Vahic oceanic realm and its closure, and likely represents erosional products of more distant orogenic zones.
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