Pochodzenie stylolitów w gipsach z czapy wysadu solnego Wapna

Abstract

Origin of stylolites in gypsum cap rock of Wapno Salt Dome (NW Poland).Summary. Stylolites have been found in a core sample from the gypsum cap rock of the Wapno salt dome (figs 1–3) at a depth of 40 m below the land surface. These structures are inclined at 40–45º to the core axis and cut by neomorphic gypsum crystals. Stylolites are products of the solution pressure. They commonly occur in carbonates but are very rarely encountered in evaporates, thus the origin and preservation of these structures in the cap rock of Wapno dome are interesting problems. Lithostatic pressure near the surface where the cap rock has been formed is insufficient to develop stylolites. Thus stylolites (Figs 4–5) in gypsum cap rock of the Wapno salt diapir are probably early diagenetic structures preserved in a fragment of Zechstein anhydrite of Z2 or Z3 cyclothems. This anhydrite block with stylolites have been carried inside intruding salt masses to the top of Wapno dome. Halite and other easy soluble minerals had been dissolved, but the anhydrites with preserved stylolites have been incorporated in the cap rock and secondary altered into gypsum, similarly to the phenomenon found in Gorleben Salt Dome by Bäuerle et al. (2000).