Microfacies of Miocene siliciclastic-carbonate deposits in the Opatówka Valley (northern marginal zone of the Carpathian Foredeep)

The study concerns the Miocene carbonate and mixed siliciclastic-carbonate deposits of the Pińczów and Chmielnik Formations. They are located on the south-eastern slopes of the Holy Cross Mountains. Based on the thin sections analysis the framework components, kinds of cements and character of porosity were described. The framework components were qualified according to their size, roundness and sorting. Two types of components predominate: carbonate intraclasts and non-carbonate extraclasts. Among the intraclasts, mainly well rounded algal bioclasts occur. Moreover, poorly rounded skeletal elements of bryozoans, foraminifera, echinoids, serpulids, bivalves, gastropods, as well as rare glauconite grains have also been observed. The extraclasts are represented mainly by quartz grains and rare litoclasts, among which fragments of sandstones and limestones were recognized. These grains are poorly rounded or angular. Overall, the framework components are poorly sorted. Microspar is the main kind of pore-filling carbonate cements. The examined deposits have considerable porosity. The following types of porosity were distinguished: intergranular, intragranular, intercrystalline, moldic and vuggy. Based on the results of thin sections analysis, seven types of microfacies were distinguished: algal foraminiferal packstone, algal packstone, quartz-rich algal packstone, lithoclastic algal packstone, quartz-rich bryozoan algal packstone, bryozoan packstone, quartz-rich bryozoan packstone