International Geological Journal - Official Journal of the Carpathian-Balkan Geological Association

NON-MARINE EVAPORITES IN THE LOWER MIOCENE OF UPPER SILESIA (CARPATHIAN FORELAND BASIN, POLAND)

Pages: 327 - 336

Authors: TADEUSZ MAREK PERYT, ZBIGNIEW BULA, STANISLAW HALAS, BARBARA OLSZEWSKA, IRENA PLUTA, BARBARA SLODKOWSKA

Abstract: A continual record of Eggenburgian to Late Badenian deposition, mostly in non-marine environments during the Early Miocene and in marine settings during the Middle Miocene time periods, was studied in the Woszczyce IG1 borehole (Zawada Basin, the Upper Silesia segment of the Carpathian Foreland Basin). In addition to the earlier-described Early Miocene foraminiferal assemblages, a Late Ottnangian pollen assemblage, which can be correlated with the MF4 Zone from Slovakia was found. Anhydrite-bearing deposits occur some 25 m below the Lower Badenian Skawina Formation. The foraminifers found immediately above the anhydrite-bearing complex and the redeposited foraminifers recorded in the lowermost part of the complex indicate its Karpatian age. The anhydrite is replacing gypsum, which originally formed displacive lenticular crystals within claystones and siltstones. The δ34S values of anhydrite (+2.17 ‰ to +9.2 ‰, average +4.4 ‰) are considerably lower and the δ18O values (+18.0 ‰ to +22.0 ‰, average +20.1 ‰) are considerably higher than the values characteristic for Miocene marine sulphates. On the other hand, the range of δ34S values found in the anhydrites of the Woszczyce IG1 borehole is similar to the range recorded in the sulphur from Carboniferous coals. The sulphate was recycled and evaporite deposits in the Woszczyce IG1 borehole, and thus in the entire Zawada Basin, formed from recycled solutes. Thus, the anhydrite-bearing sequence originated in a non-marine environment, in which periodically saline conditions prevailed.

Keywords: Karpatian, lacustrine environment, Ottnangian palynomorphs, oxygen isotopes, sulphur isotopes, anhyd

Download PDF document Show Text Version