Palaeogeographical zonation of gypsum facies: Middle Miocene Badenian of Central Paratethys (Carpathian Foredeep in Europe)

Abstract

Studies on Middle Miocene Badenian gypsum in various parts of Central Paratethys, the oldest widespread primary marine gypsum, in western Ukraine, southern Poland and Moravia (Czech Republic) indicate that there are three principal gypsum facies: crystalline gypsum, stromatolitic gypsum and clastic gypsum. The latter typically occurs between crystalline and stromatolitic gypsum and between stromatolitic gypsum and the land. In addition, it is common in channels within gypsum microbialites, and is the main facies during the deposition of the upper part of Badenian gypsum when important bathymetric differences existed within the marginal part of the Carpathian Foredeep Basin, the largest foredeep basin in Europe. Within crystalline gypsum facies, it is observed the overall size of the crystals increases and that the layering declines towards the permanent, stabilized brine body, and thus the giant gypsum intergrowths–non-layered coarse-crystalline selenite – is the end-member of gypsum facies continuum. Typically it passes into layered selenites although owing to fluctuations of pycnocline level, some transitional gypsum subfacies may be missing both in the vertical section as well as in particular outcrops. The following important controls on the development of gypsum facies have been identified: pycnocline level fluctuations, brine level fluctuations including brine sheets and floods, rare marine transgressions, pedogenesis leading to “alabastrine” gypsum development, and rate of inflow of continental water.