Paleoecology and lithogenesis of the Middle Miocene (Badenian) algal-vermetid reefs from the Roztocze Hills, south-eastern Poland

ABSTRACT: The Middle Miocene (Badenian) algal-vermetid reefs of the Roztocze Hills (Lublin Upland, south-eastern Poland) are built mostly of laminar crusts of coralline algae, shells of sessile gastropods Petaloconchus intortus (LAMARCK), and various amount of detrital internal sediments. The secondary encrusters of a reef frame are bryozoans, serpulids, foraminifers, and cirripedes Verruca . Seven species of coral line algae are common among 21 species found in reef deposits. CoralIines show most species in common with the Ukraine and only some with the Vienna Basin. Of the two ecological assemblages recognized, viz. the reef assemblage and the epi-reef assemblage, the first one inhabited the reef during its growth, and was structured mainly by the presence of hard bottom with abundant fissures and cavities. The second one inhabited the surface of the already dead reef, and it was structured by the presence of hard bottom and ubiquitous noncalcifytng·submarine flora. The reef has developed on positive elements of the·sea bottom in extremely shallow water, under high hydrodynamic conditions, normal salinity, and climate comparable to the present-day eastern part of the Mediterranean. Intensive submarine cementation has initiated the diagenetic evolution of reef rocks. Late diagenetic features in the investigated reefs are attributed to changes in local continental (Upper Miocene till Holocene) environments associated with wandering level of local ground-water tables.