Geneza struktur gruzłowych w wapieniach dębnickich (żywet/fran) w świetle badań sedymentologicznych i analizy zawartości izotopów stałych węgla i tlenu

Abstract

GENESIS OF NODULAR STRUCTURES IN THE DĘBNIK LIMESTONES (GIVETIAN/FRASNIAN) IN THE LIGHT OF SEDIMENTOLOGICAL STUDY AND ANALYSIS OF STABLE ISOTOPES OF CARBON AND OXYGEN Summary The Upper Givetian - Lower Frashian carbonate sequence crops out in the Dębnik area, Cracow Upland. These sediments have been studied in order to reconstruct a genesis of nodular structures of some units of these limestones. Basing on sedimentologicaI observations the following, different structural and genetic types of nodular limestones have been recognized: Type I - nodular and wavy limestones composed of isolated oval and elipsoidaI nodules resting within marly matrix. These limestones orginated during early diagenetic concretionary carbonate cementation and subsequent pressure solution during burial. Type II - flaser - nodular limestones, formed due to pressure solution during late burial diagenesis. Type III - nodular limestones of conglomerate type, built up of irregular fragments of limestones produced due to erosion and reworking differentialy consolidated carbonate deposits. Stable isotope composition supports results of sedimentological studies - an idea of diagenetical origin of nodular structures.