MAJOR SEA-LEVEL FLUCTUATIONS IN THE LATE PERMIAN ZECHSTEIN BASIN OF POLAND: RESULT OF THE INTRACONTINENTAL POSITION OF A MARINE BASIN

The Upper Permian Zechstein sequence in Poland is underlain by eolian sandstones which apparently were little affected by the transgressing Zechstein sea what was previously interpreted as due to catastrophic flooding, lasting several weeks to several months, of the intracontinental depressions located several hundred meters below the contemporaneous sea-level. When the marine conditions were established during the deposition of the first Zechstein cycle carbonate, several episodes of several episodes of sea-level fluctuations are recorded that are characterized by slow regression and rapid return to deep-water conditions, and these are interpreted as due to (glaci)eustatic changes. At the end of the first Zechstein cycle carbonate deposition a radical sea-level fall resulted that in the basinal area oncolithic-stromatolitic deposits have been accumulated. This major sea-level fall is interpreted as due to evaporite drawdown. During the deposition of the second Zechstein cycle carbonates, several episodes of the sea-level fluctuations are recorded as well and they are also interpreted as due to (glaci)eustatic changes, and the major sea-level fall at the end of the second Zechstein cycle carbonate deposition resulted in the formation of carbonate platform at the lower slope of the Zechstein evaporite-carbonate platform. This major sea level fall was due to evaporite drawdown. The record of sea-level fluctuations in the Polish Zechstein basin indicates that the triggering mechanisms responsible for the major sea-level fluctuations were: tectonics in the border area with the open sea (the Zechstein transgression) and the evaporite drawdown (the end of the first and the second Zechstein cycle carbonates).