Late Cretaceous Syn-Inversion Sedimentation in Vicinity of Compressionally Reactivated Salt Structures from the Mid-Polish Trough

Piotr Krzywiec
Polish Geological Institute, Warsaw, Poland

The Permian to Cretaceous Mid-Polish Trough evolved above the Tornquist-Teisseyre Zone - crustal boundary between the Precambrian and the Palaeozoic Europe. It was filled by several kilometers of siliciclastics and carbonates, with thick Zechstein (approx. Upper Permian) evaporites at its base. Late Cretaceous multi-stage inversion of the Mid-Polish Trough resulted in significant activation of various salt structures (salt pillows, salt diapirs) built of the Zechstein salt, that were at least partly initiated during earlier (Mesozoic) basin’s extension/subsidence. Within the central (Kuiavian) part of the MPT, the Klodawa salt diapir grew in Triassic and Jurassic times. During Late Cretaceous basin inversion, the Klodawa salt structure was reactivated, with important part of deformation being accumulated by folding of large salt overhang, formed in Late Triassic. Because of large degree of post-inversion erosion almost entire sedimentary record of the inversion tectonics has been removed, with only subtle seismostratigraphic features pointing to the Late Cretaceous sedimentation linked to growth of compressionally-reactivated Klodawa salt diapir. Within the NW (Pomeranian) part of the Mid-Polish Trough, salt structures were also significantly reactivated during shortening and inversion of the basin. Smaller amount of post-inversion uplift resulted in better preservation of sedimentary record of growth of salt structures. It includes upturned beds, thickness reductions, localized and partly folded unconformities, and onlapping / downlapping patterns. All these features point to progressive growth of salt structures triggered by regional compression. One of the key parameters that controlled Late Cretaceous sedimentation in vicinity of reactivated salt structures was thickness of mobile salt substratum.

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas