The Waulsortian-type mound in the Lower Namurian of the Lublin Basin (SE Poland)

A unique Waulsortian-like mound is recognized in the Lower Namurian succession of the central part of the Lublin Basin (SE Poland). The Carboniferous succession is characterized here by Yoredale-type cyclothems with carbonate units of relatively constant thickness. An unexpected increase in thickness of the carbonate unit in the Minkowice-4a well indicates the occurrence of an organic buildup at least 35 m thick. Sedimentological analysis reveals that its skeletal composition as well as its peloidal matrix, abundant stromatactoid cavities and succession of cements indicate close analogies to similar facies in Lower Carboniferous Waulsortian-type mud-mounds. Oxygen isotope data indicates that the formation and growth of the described mound were probably stimulated by hot water vents. The occurrence of hot water vents in the open marine setting of the Lublin Basin is interpreted as a consequence of Early Namurian tectonic activity, when a local tectonic compressional regime occurred in some parts of the basin. The mound does not function as a hydrocarbon reservoir, however, its characteristics point to the presence of sedimentary traps, which hitherto have not been recognized in this region. (C) 2004 Elsevier Ltd. All rights reserved.