MIKROFACJE I DIAGENEZA BARIEROWYCH UTWORÓW DOLOMITU GŁÓWNEGO (Ca2) NA OBSZARZE POMORZA ZACHODNIEGO

Abstract

BARRIER MICROFACIES AND DIAGENESIS OF THE MAIN DOLOMITE (Ca2) STRATA IN THE WEST POMERANIA AREAAbstract. Microfacies and diagenetic characteristics of four profiles representing outer barrier environment of the Zechstein Main Dolomite (Ca2) have been performed in the area of the Kamień Pomorski (Benice-3, Ciechnowo-5) and Pomorze (Czarne-1, Gardomino-1) carbonate platforms. The profiles contain the following types of the dolostone microfacies: ooid grainstones and packstones, bioclastic wackstones, intraclast floatstones and rudstones, microbially stabilized mudstones and biogenic forms such as microbial mats and stromatolites. Microbial biostabilization is very common. Two stages of diagenesis have been distinguished: eodiagenesis - which only slightly affected the high primary porosity and mesodiagenesis associated with the gradual burial which played an essential role in lowering of the reservoir potential of the rocks. Aggradational neomorphism, chemical compaction and diverse cementation processes also acted at this stage. Fracturing of the rocks happened in some places causing formation of the potential migration routes for hydrocarbons and mineralized solutions. The studies confirmed previous opinions that the Main Dolomite rocks deposited in the barrier zones of West Pomerania have in general poor reservoir properties.