Cenozoic dynamics of the Dębina Salt Dome, Kleszczów Graben, inferred from structural features of the Tertiary-Quaternary cover

The Dębina Salt Dome (DSD) is located in the central part of the Tertiary Kleszczów Graben, between the open-cast brown coal mines: "Bełchatów" and "Szczerców". Complicated geological features of the DSD are related to the polyphase tectonic activity in the Kleszczów Graben, and the salt structure dynamics which is believed to be coupled with that activity. The distinctive anticlinal elevation of the sedimentary cover of the DSD points to Cenozoic uplift of the salt. The timing of these salt pulses can be considered as related to main phases of tectonic activity in the Tertiary and Quaternary, well-documented during field studies in the brown coal open mine "Bełchatów". Due to the Middle/Late Tertiary salt uplift, a vast asymmetric anticline of up to 400 m amplitude was formed in the Early Miocene sandy and coaly sediments, including the so-called main coal seam. Renewed salt movements of the DSD occurred in the Quaternary. Considering the magnitude of the top-Tertiary surface elevation versus preliminary dating of this activity, it is concluded that the rate of the salt uplift was about 0.3 mm/ year, with the strain rate estimated at 4 x 10-14 s-1. Both parameters show relatively fast Quaternary salt movements of the DSD, being representative for the diapir rise active phase (from 10-14 s-1 to 10-16 s-1 ).