Jurassic evolution of the Pomeranian segment of the Mid-Polish Trough - basement vs. salt tectonics and subsidence patterns

• Autorzy: Krzywiec P.
• Konferencja: International Congress on the Jurassic System (7 ; 06-18.09.2006 ; Kraków, Poland)
• Języki publikacji: EN

Abstrakty

EN

The Mid-Polish Trough (MPT) formed the axis of the Polish Basin that forms part of the Permian-Mesozoic system of West- and Central-European epicontinental basins. Prior to its Late Cretaceous-Paleocene inversion, the MPT was filled with several kilometres of Permian and Mesozoic sediments, including thick Zechstein salts that gave rise to the development of a complex system of salt structures in the central and northwest segments of the MPT. Thick Zechstein salts acted on a basin-wide scale as a mechanical decoupling layer during the Mesozoic evolution of the MPT. Due to this regional decoupling effect, Jurassic extensional faulting was mostly restricted to the sub-Zechstein salt basement whilst normal faulting played a subordinate role in the Jurassic syn-extensional sedimentary series that are characterized by gradual lateral thickness changes (Fig. 1A). Basement fault zones were reactivated as reverse fault zones during inversion of the Mid-Polish Trough that led to formation of the Mid-Polish Swell (Fig. 1A). Taking into account: the location of Mesozoic thickness gradients, the structural configuration of the sub-Zechstein basement, and the location of salt structures - a new tectonic map was constructed showing the inferred sub-salt fault zones that were active during the subsidence and inversion of the Pomeranian part of the MPT (Fig. 1B; cf. Krzywiec 2006). The NE boundary of the MPT was generally controlled by the SW margin of the East-European Craton, whilst its SW boundary coincides with a complex system of fault zones most probably inherited from earlier tectonic phases. Comparison of isopach maps of the Jurassic series (Dadlez 2003; Fig. 1C-E) with inferred sub-Zechstein fault zones shows the prominent role of these fault zones in development of the Jurassic sedimentary infill of the Pomeranian segment of the Mid-Polish Trough. The isopach map of Lower Jurassic series (Fig. 1C) shows a distinct thickness increase towards the axial parts of the MPT where they were partly eroded in response to inversion movements. Similarly, Middle Jurassic series have been deeply truncated and partly or even totally eroded due to the inversion-related uplift of the Mid-Polish Swell. Consequently, for these areas, the isopach map given in Fig. 1D shows tentative values only, with observed thickness values being restricted to the marginal and SE axial parts of the basin. Nevertheless, the gross thickness distribution is compatible with the concept of activity along inferred sub-salt basement fault zones controlling basin subsidence. The Upper Jurassic thickness map (Fig. 1E) is the least reliable map due to relatively widespread erosion of this complex caused by inversion and uplift of the axial part of the Mid-Polish Trough. Overall thickness changes within this complex are moderate, and they generally coincide with inferred basement fault zones. Regional thickness increase towards the SE suggests increased influence of the Tethyan domain on evolution of the Mid-Polish Trough.

Słowa kluczowe

EN

N Mid-Polish Trough; Jurassic; decoupling; basin subsidence; seismic data; salt tectonics

• Wydawca: Państwowy Instytut Geologiczny - Państwowy Instytut Badawczy
• Czasopismo: Volumina Jurassica
• Rocznik: 2006
• Tom: Vol. 4, no. 1
• Strony: 54--56
• Opis fizyczny: Bibliogr. 2 poz.

Twórcy

autor

Krzywiec P.

• Polish Geological Institute, ul. Rakowiecka 4, PL-00975 Warsaw, Poland,

Bibliografia

• 1. Dadlez R. 2003. Mesozoic thickness pattern in the Mid-Polish Trough. Geological Quarterly, 47, 3: 223-240.
• 2. Krzywiec P. 2006. Triassic-Jurassic evolution of the Pomeranian segment of the Mid-Polish Trough - basement tectonics and subsidence patterns. Geological Quarterly, 50, 1. (in press)