WARUNKI ANHYDRYTYZACJI GIPSÓW BADEŃSKICH W ZAPADLISKU PRZEDKARPACKIM

Abstract

CONSTRAINTS OF ANHYDRITIZATION OF BADENIAN GYPSUM DEPOSITS IN THE CARPATHIAN FOREDEEP

Abstract. The gypsum is replaced by anhydrite in the temperature dependent on the physicochemical environment of gypsum. Most Badenian anhydrite deposits in the Polish Carpathian Foredeep Basin display sedimentary and petrographic features of diagenetic facies formed from the precursor gypsum, both selenitic (autochthonous) and clastic (allochthonous). The irregular distribution of anhydrite within the gypsum succession suggests the replacement occurred preferentially in zones of high microporosity in the contact with highly saline pore fluids. Many controlling factors, related to sedimentary and diagenetic environments, have been involved in anhydrite genesis in the Badenian evaporite basin. The burial environments of sulphate deposits in the Carpathian Foredeep were considered to estimate the predicting depths and time of the gypsum to anhydrite transition. The obtained depths range between 630 and 740 m for the basinal succession and between 610 and 700 m for the marginal succession. Because in the northern part of the Carpathian Foredeep gypsum has never been deeply buried, different factors not related to deep burial conditions (e.g. salinity of pore fluids) must have been involved in anhydritization processes.