Naslov
Peritidal cycles in the Lower Cretaceous of Istria (Croatia)

Autori
Füchtbauer, Hans ; Tišljar, Josip

Izvornik
Sedimentary Geology (0037-0738) 14 (1975); 219-233

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
peritidal cycles; early-diagenetic dolomite; dolomitization cycles; Lower Cretaceous; Istria; Croatia

Sažetak
Different types of peritidal and subtidal cycles (dolomitization cycles, mickocrack cycles, and oncolite cycles) have been found in the Lower Cretaceous of Istria. A detailed description is given for light, cryptocrystalline dolomites with desiccation cracks, soft pebble conglomerates, and algal mats in Berriassian (after geological map wrong - Hauterivian), which presumably formed in the supratidal realm early in diagenesis. They alternate on a 0,5-m scale with dark-gray, macrocrystalline, late-diagenetical dolomites, the contrasting colour of wich is mainly caused by the coarse crystal size. Both dolomites consist of Ca0.55Mg0.45CO3, pointing to a climate similar to that of the Florida Keys.The rest of the Cretaceous and uppermost Jurassic carbonate rocks were deposited in shallow and deeper-marine environments. It is suggested that the general trend of an Early Cretaceous regression and transgression is in harmony with worldwide eustatic sea-level changes and therefore need not be explained only by local tectonic events.

Izvorni jezik
Engleski

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