Warunki sedymentacji osadów cechsztynu w niecce północnosudeckiej

Paweł Raczyński

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DEPOSITIONAL CONDITIONS AND PALEOENVIRONMENTS OF THE ZECHSTEIN DEPOSITS IN THE NORTH SUDETIC BASIN (SW POLAND)

Summary
Zechstein deposits accumulated in various sedimentary environments which may be grouped into three broad realms: shallow marine, diversified nearshore and flat onshore. Tempestites and related deposits have commonly been documented throughout the Zechstein succession of the basin. Avertical succession which includes deposits accumulated in shallow, narrow bay settings at the base and grades upwards into deposits of carbonate barrier, enclosed lagoon with restricted water circulation, and finally into sediments of onshore sand-mud flat, appears the most commonly recorded pattern ofpaleoenvironment evolution. Two major transgressive-to-regressive depositional complexes encountered within the sedimentary succession of the North-Sudetic Basin are attributed to PZl (Werra) and PZ3 (Leine) cyclothems of the classic subdivision of the Central European Zechstein deposits. Deposits ofthe top most part ofPZ3 cyclothem are equivalents of the Permo-Triassic transitional terrigenous series (pzt). Most boundaries of the distinguished lithostratigraphic units are diachronous. The latter conclusion does not apply to the lower boundaries of the Zechstein (Group?), Lead-bearing Marls (Member?) and Plate Dolomite (Member?) - all of them seem to be almost isochronous. Predominant number of the diversivied fossil taxa (120 taxa documented, including ca. 40 recorded for the first time from the area) discovered within the Zechstein deposits of the North-Sudetic Basin cannot be regarded as good chronostratigraphic indicators. The only exception is the calcareous algae of Calcinema permiana (King) which have high biostratigraphic value. A great part of the remaining taxa served as good biofacies indicators and helped while interpreting paleoenvironments.

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