Wpływ wczesnej diagenezy na kształtowanie fizycznych własności mioceńskich wapieni organodetrytycznych Roztocza

Abstract

O własnościach fizycznych mioceńskich wapieni organodetrytycznych Roztocza zadecydowały: migracja stref facjalnych, słaba intensywność morskiej cementacji międzyziarnowej, spowodowana charakterem środowiska sedymentacji, niewielkie rozprzestrzenienie stref intensywnej cementacji słodkowodnej (lądowej) oraz długotrwała ekspozycja kompleksów węglanowych na oddziaływanie niedosyconych CaCO3 wód atmosferycznych. Świadczy o tym porównanie wyników badań składu ziarnowego i chemicznego, struktur sedymentacyjnych oraz struktur diagenetycznych z wynikami badań własności technicznych omawianych wapieni. The early diagenesis, influence on forming of phisical properties of Miocene biodetrital limestones from Roztocze HillsThe examined Middle Miocene biodetrital limestones were deposited in the sublittoral and littoral zone of the Carpathian Foredeep basin (Fig. 1). The biodetrital series are interbedded by sediments of others zones, characteristic to different development stages of reef complexes (Fig. 2). The comparison of investigation results of granular composition (Tab. 1-4), chemical and mineral composition (Tab. 5,6), sedimentary structures, diagenetic textures (Tabl. I-V, Figs 3-18) and physical properties (Tab. 7), served as a basis for following sugestions. Formation of physical properties of examined biodetrital limestones was determined by diagenetic processes, first and foremost by cementation and leaching. An intensive intra- and intergranular cementation strenghten limestones construction, exerting a positive influence on their phisical properties. An intensive leaching of CaCO3 gives a reverse effect. The greater part of examined biodetrital limestones is almost devoid of intergranular cements. Mechanical unstability of deposit grains, caused by turbulent character of sedimentation environment, was one of the major factors restricting marine intergranular cementation. An intensive freshwater cementation is developed only in isolated horizons and lenses which maximal thickness reaches a few meters. The limestones series, since Lower Sarmatian to present day have been exposed on activity of atmospheric waters, undersaturated in relation to CaCO3. That, has been conductive to formation of secondary porosity system, which exerted a negative influence on limestones physical properties. The differentiation of diagenetic processes sequences, and their heterogenous intensity, as well as frequent changes in sedimentary environment character, were responsible for differentiation of examined rocks physical properties.