Abstract The Late Palaeozoic deposits in Croatia were derived from the Palaeotethyan shelf areas along the northern Gondwana passive continental margin and consist of mixed carbonate–clastic facies. These sedimentary rocks accumulated in the equatorial area along northern Gondwana under a dominantly hot climate and laid the foundations for the future Adriatic Carbonate Platform (AdCP). Detailed classification and geochemical studies of the Permian and Permian–Triassic deposits in most parts of Croatia are still in progress, especially concerning palaeoclimate and regional palaeogeography. The best preserved Permian outcrops can be found in the Velebit mountain area, including continuous Permian–Triassic sections. Stable isotopes of carbon and oxygen from carbonates, with characteristic positive δ 13 C carb excursion during the Late Permian and negative δ 13 C carb excursion at the Permian–Triassic transition combined with palaeontological and sedimentological data, helped in palaeoclimate estimations and the positioning of the chemostratigraphical Permian–Triassic Boundary (PTB). Sedimentological, palaeontological and geochemical data indicate that deposition in the Permian took place mainly in shallow-water tropical areas under oligotrophic conditions. High carbon isotope ratios in Capitanian carbonate rocks (+4 to +6‰ VPDB) mark the ‘Kamura event’ characterized by temporary cooling, high productivity and burial rate. Evaporites in the central part of the Karst Dinarides and red beds of the ‘Gröden type’ indicate a warm and mostly arid climate. Calculations based on the oxygen isotopic compositions of whole-rock carbonate and fossil samples estimate latest Permian temperatures up to 26 °C.

Abstract The Mesozoic, mid-Cretaceous (Barremian to Cenomanian) deposits of southern Croatia comprise a succession of shallow tropical-water, inner-platform deposits that formed on a Bahama-type isolated Adriatic carbonate platform in the Dinarides. This succession is dominated by benthic foraminifers and dasycladalean algae, and is exposed in a nearly continuous outcrop section on the islands and along the coast of southern Croatia. It has been studied in terms of sedimentary facies, paleoecology, and biostratigraphy. The present study documents that several species of benthic foraminifers (cuneolinids, orbitolinids, alveolinids) and dasycladalean algae (Salpingoporella) have exceptional age-diagnostic value for mid-Cretaceous biostratigraphy. These are abundant, and they have a widespread distribution and a restricted stratigraphic range. They evolved rapidly and became extinct suddenly. The mid-Cretaceous benthic associations, including a total of 106 species and 57 genera of benthic foraminifers and 48 species and 20 genera of dasycladalean algae, were analyzed to establish the principal diversity patterns at (sub)stage level of resolution. The Early Aptian marked the foraminiferal diversity maximum, whereas significant diversity drops are recorded in the Late Aptian and Early Cenomanian. The foraminiferal distribution within the oligotrophic habitats of the platform interior was controlled primarily by relative sea-level oscillations, variations in oceanic circulation rate, and nutrient availability in surface waters. There is a positive correlation between episodes of increased diversification and the regional relative sea-level rises, whereas regressive episodes resulted in reduction of oligotrophic habitats and decreased species richness. The dasycladaleans were the most diversified during the tidal-flat-dominated Barremian, and from that peak diversity decreased through the Early Aptian. A significant diversity drop occurred in the Late Aptian, and it was contemporaneous with the maximum abundance of Salpingoporella dinarica . The mid-Cretaceous dasycladaleans never fully recovered from the Early Aptian platform deepening event, and their post-Aptian diversity pattern implies dependence on factors other than relative sea level and associated changes in habitats. Geologic Problem Solving with Microfossils: A Volume in Honor of Garry D. Jones SEPM Special Publication No. 93, Copyright © 2009 SEPM (Society for Sedimentary Geology), ISBN 978-1-56576-137-7, p. 153–170.