GYPSUM-TO-ANHYDRITE TRANSITION IN THE MIOCENE OF SOUTHERN POLAND

Gypsum deposits in the Carpathian Foredeep of southern Poland were alt ered during burial to anhydrite. This alteration did not completely de stroy primary lithologic features. Different gypsum lithotypes have eq uivalents in the altered sulfate sections. Relies of, and pseudomorphs after, crystalline and sedimentary structures indicate that extensive replacement and cementation occurred early during burial diagenesis. The replacement of gypsum by anhydrite was probably initiated in the s hallow subsurface by high temperature and/or reaction with brines of h igh salinity. Accordingly, the importance of a deep burial for gypsum diagenesis in the studied area may have been overestimated.