Kajper czy pstry piaskowiec? Problemy lito stratygrafii triasu kujawskiego odcinka wału środkowopolskiego
Abstract
KEUPER OR BUNTSANDSTEIN? PROBLEMS OF LITHOSTRATIGRAPHY OF THE TRIASSIC OF THE KUJAWY SEGMENT OF THE MID-POLISH RIDGE
Summary
The paper present a revised lithostratigraphic subdivision of Triassic deposits in several deep boreholes from a section crossing the central part of the Kujawy sector of the Mid-Polish Ridge. The revision is based on a detailed interpretation of well log data. Grave errors in the lithostratigraphic subdivision of the Triassic in some hitherto published and unpublished borehole profiles were found, which change the thickness of individual series (e.g., of the Keuper in the reference borehole Krośniewice IG 1) from 2000 to 300 m only or of stages (e.g., of the Upper Keuper in the borehole Rdutów 2) from 1570 to 311 m only. Large borehole sections hitherto assigned to the Keuper belong in fact to the Muschelkalk and especially the Buntsandstein. Also a number of regional disconformities in the whole Triassic section of the area studied where recognized. The Triassic depositional trough of this area was already in Late Triassic (exactly Upper Keuper) time uplifted and converted into an inversion ridge. The results obtained open anew the question of the origin of the Polish Trough and the processes which controlled their depositional and structural development.
Summary
The paper present a revised lithostratigraphic subdivision of Triassic deposits in several deep boreholes from a section crossing the central part of the Kujawy sector of the Mid-Polish Ridge. The revision is based on a detailed interpretation of well log data. Grave errors in the lithostratigraphic subdivision of the Triassic in some hitherto published and unpublished borehole profiles were found, which change the thickness of individual series (e.g., of the Keuper in the reference borehole Krośniewice IG 1) from 2000 to 300 m only or of stages (e.g., of the Upper Keuper in the borehole Rdutów 2) from 1570 to 311 m only. Large borehole sections hitherto assigned to the Keuper belong in fact to the Muschelkalk and especially the Buntsandstein. Also a number of regional disconformities in the whole Triassic section of the area studied where recognized. The Triassic depositional trough of this area was already in Late Triassic (exactly Upper Keuper) time uplifted and converted into an inversion ridge. The results obtained open anew the question of the origin of the Polish Trough and the processes which controlled their depositional and structural development.