Sinicowe struktury biosedymentacyjne w wapieniach dinantu w rejonie Krzeszowic

Abstract

ALGAL BIOSEDIMENTARY STRUCTURES OF DINANTIAN LIMESTONES IN THE AREA OF KRZESZOWICE NEAR CRACOW Summary Biosedimentary algal structures are important components of over 1000 m series of Dinantian carbonate rocks cropping out in the Krzeszowice area near Cracow. There were differentiated a number of macroforms of these structures according to morphological features including geometry of algal mats, the presence or lack of lamination, attachment to bedrock, etc. Besides common Phanerozoic structures of the stromatolite and oncoid types, there were identified some rarer ones such as trombolites, subaerial stromatolites occurring in proximity of caliche covers, and complex stromatolites built due to parallel growth of algae and other benthic skeletal organisms (serpulids, vermetoidal gastropods, bryozoans and Rhodophyta). A model of distribution of individual macroforms in Dinantian sedimentary basin, reconstructed on the basis of facies analysis, confirms the value of these structures as a tool in paleogeographic and paleoecological reconstructions. They are especially useful for tracing subtle changes in bathymetry and salinity of environments adjoining tidal zone and lagoon ones.