WSKAŹNIKI ŚRODOWISKOWE BADEŃSKICH SKAŁ SIARCZANOWYCH W ZAPADLISKU PRZEDKARPACKIM

Abstract

ENVIRONMENTAL MARKERS OF BADENIAN Ca-SULPHATE ROCKS IN THE CARPATHIAN FOREDEEPAbstract. Ca-sulphate rocks (gypsum and anhydrite) form in a wide-range of environmental settings from marginal (subaerial and very shallow subaqueous) through shallow to deep subaqueous, at the subsurface and in burial. Based on modern analogues, environmental markers: (i) sedimentary (e.g., lamination, current marks, mikrobial structures, dissolution and erosion surfaces, crystalline structures, sulphate nodules), (ii) petrographic and mineralogical (mineral composition and paragenesis, fabrics), and (iii) geochemical (e.g., major and minor elemental composition, isotopic composition of sulphur, oxygen and strontium) provide useful information on the depositional and diagenetic environment for the ancient sulphate deposits. The results of the complex sedimentological, petrographic and geochemical studies of Badenian sulphate deposits from different parts of the Capathian Foredeep basin indicate distinct sedimentary conditions, which represent the main depositional systems (subaerial, shallow and deep subaqueous) of the salina basin. Gypsum deposits formed in these settings underwent a particular pathways of diagenetic evolution and an alteration into anhydrite. In the marginal settings selenite and microbial facies formed, that underwent synsedimentary and early-diagenetic anhydritization (via nodule formation) at the surface. In deeper, central parts of the basin mainly clastic gypsum deposits formed. Laminated anhydrite and breccias are deep-water, redeposited clastic deposits (originally gypsum), that were transformed into anhydrite under burial in different stages of diagenesis. In the basin centre anhydrite shows features characteristic of basinal facies formed in euxynic conditions. The results suggest the different depositional and diagenetic regimes between the basin margin and central part, and large non-marine (riverine, groundwater) inputs to the basin during sulphate formation.