Growth forms and distribution patterns of stromatoporoids exposed on Devonian palaeobottom surfaces; Holy Cross Mountains, central Poland

Abstract

Well preserved palaeobottomsurfaceswith stromatoporoids are exposed in twoDevonian localities in the Holy Cross Mountains in central Poland: Skały and Bolechowice-Panek quarries. The stromatoporoids were subjected tomorphometric analysis and distribution studies. Stromatoporoids were studied hitherto only in vertical cross sections; the study of three-dimensional stromatoporoid domes has created a need to introduce a new set of parameters describing their shapes, which includes: horizontal length and width, vertical height, elongation ratio and elongation azimuth. In order to make the measurements made by various methods comparable, and thus to allow comparable interpretations, recalculation formulas have been presented. Comparison of the results obtained by the two methods indicates that the measurements made in vertical cross sections substantially bias the dimensions and shapes of the stromatoporoids, which may influence stromatoporoid-based palaeoenvironmental reconstructions. The results of the measurements were interpreted in terms of palaeonvironmental conditions. In Bolechowice-Panek the stromatoporoids lived in a quiet shallow water setting with a low and stable sedimentation rate. In Skały the stromatoporoids grew in a shallow subtidal setting and located themselves on parallel ripples,most probably to escape being buried by deposits accumulating in inter-ripple depressions.