Budowa geologiczna i geneza mioceńskiego zrębu Ryszkowej Woli w rejonie Sieniawy – Rudki (wschodnia część zapadliska przedkarpackiego) — wyniki interpretacji danych sejsmiki 3D

Abstract

Geological structure and origin of the Miocene Ryszkowa Wola Horst (Sieniawa–Rudka area, eastern part of the Carpathian Foredeep Basin) — Results of 3D seismic data interpretation.S u m m a r y. The Miocene Carpathian Foredeep Basin in Poland (CFB) developed in front of the Outer Carpathian fold-and-thrust belt, at the junction of the East European craton and the Palaeozoic platform. Within the upper Badenian through Sarmatian deposits of its eastern part, the CFB hosts numerous gas fields. The gas-bearing Miocene succession is characterised by a shallowing-upward trend of sedimentation and consists of offshore hemipelagic, turbiditic and deltaic and nearshore-to-estuarine facies associations. The foredeep basin formation was largely controlled by the structure of its Neoproterozoic–Early Cambrian basement, especially by NW–SE trending faults inherited from Mesozoic tectonic history of SE Poland (subsidence and inversion of the Mid-Polish Trough). Several NW–SE-elongated, narrow basement pop-up structures developed in the northeasternmost part of the CFB, one of them being the Ryszkowa Wola block. The uplift of the pop-up basement block involved Miocene reactivation of older fault zones and resulted in the formation of a narrow, NW–SE elongated Ryszkowa Wola horst (RWH) above it, within the Miocene strata. A complex system of right-stepping, en-echelon, mainly normal faults of predominantly E–W trend, branching off from the NW–SE-striking boundaries of the RWH, has developed around and above the horst, leading to compartmentalisation of the Miocene succession into numerous, mutually displaced and rotated fault blocks. Such an association of deformation structures recognised from the 3D seismics was interpreted in terms of transpressive conditions with the horizontal maximum tectonic compression axis directed ± E–W and a sinistral strike-slip displacements on NW–SE striking faults in the basement. The structural interpretation of the Ryszkowa Wola structure proposed here is in line with published results of analogue modelling of fault patterns in sediments overlying active strike-slip discontinuities in a rigid basement. The basement-cover interaction within the Ryszkowa Wola structure in the area of Sieniawa–Rudka was partly coeval with the Miocene deposition of the CFB infill. The uplift and horizontal displacements of the Ryszkowa Wola basement block modified the local subsidence pattern and the organisation of Miocene depositional systems. The syn-depositional strike-slip fault activity in the basement of the CFB resulted in differential movements and rotations of kinematically linked fault-blocks in the Miocene succession around and above the RWH, leading to the formation of numerous gas traps.